chromosome fixation in evolution

[antonT]

Is the fixation of a chromosomal aberration pure chance?

[Copasetic]

Is the fixation of a chromosomal aberration pure chance?

This is reposted. Maybe it will help you some.

This actually well understood in biology -Some of the mechanisms that can allow unequal number of chromosomes to exist in populations.

Let's first talk for a moment about a few mechanisms that can change the number of chromosomes in an individual. First I think it would be best to quickly define some parts on a chromosome, such that you may easily follow along Yeti.

A chromosome is composed of two sister chromatids. At each end of the chromatid is a an area called a telomere, which we can say for now simply helps to protect the DNA on the chromatid. In the middle of each chromatid is an area called a centromere, which is kind of like a "sticky latch" that holds the two chromatids together, as well as provides an anchor for tubule attachment during replication. The centromere is not perfectly in the center of the chromatids, which creates a a long arm and a short arm of the chromatids. We often denote the short arm "p" and the long arm "q". I've included a few pictures below to help you visualize it.

Ok, on to the fun stuff. The author claims that "There is no gradual way to go from one even number to the next even number", which as I said already, I dispute. There is gradual ways where uneven numbers of chromosomes can be maintained in populations. Let's check some out.

Robertsonian fusions (translocations)

This kind of fusion happens when the long arms of two nonhomologous acrocentric (meaning centromeres located close to the ends) fuse at the centromere and the short arms are lost. The important part here is that none of the genetic "information" is lost. In humans this often happens in chromosomes 13, 14, 15, 21 and 22 -Because they are acrocentric and the short arms contain no pertinent genetic material.

Allow me to illustrate with MS Paint!

(Keep in mind I have only drawn 1 sister chromatid to keep the illustration more simple)

This happens more than just cartoon drawings. It happens (as I said) in people all the time -The people with Robertsonian fusions are perfectly normal, save the translocation. Without karyotyping them, you would never know they had the translocation. It is also interesting to note that these people have only 45 chromosomes and reproduce fine. Which wholly and immediately destroys the authors argument that "There is no gradual way to go from one even number to the next even number".

There are literally thousands of people walking around with karyotypes such as this:

Who are perfectly normal.

(Well the board just informed me I have too many images in one post , So I will divide this up into two posts)

[Copasetic]

Ok let's continue

Let's step away for a moment from a 13-14 Robertsonian translocation and look at another example, one involving chromosomes 14 and 21. When one of these 45 chromosome individuals reproduce they can have progeny as defined by the illustration below:

As you can see, 2 of the combinations of gametes result in 2 progeny with extra or missing chromosomes -In modern society these individuals survive because our technology, but in a pretechnological society they would likely not fair well. One combination of gametes results in a "normal" offspring with "normal" chromosomes. And one combination results in a "normal" offspring who is a carrier of the 45 chromosome condition (the translocation).

Let's get hypothetical for a moment and say this is occurring in a small isolated population. The individual who's make up is;

Happens to have a mutation on the 21q portion of the 14q21q chromosome which produces a selective advantage (which I am guess you have no problem in accepting since you 'believe' in adaptations). By the way let's call it chromosome N from now on, to keep it easy.

So individuals with chromosome N;

have a greater fitness in this population then those without it.

So what happens? The incidence of individuals with 45 chromosomes increases in the population (the carriers). This also means that more individuals with only 45 chromosomes will be mating with each other. Now this gets interesting, lets look at the possible offspring produced from these matches. Below I have made an image of the outcomes, looks complicated but allow me to explain so it is not.

Hopefully it is not too small, so you can follow along. If it is download it and resize it.

The top left corner shows 2, 45 chromosome individuals who will mate. The top right corner shows the possible gametes produced by each of the individuals.

The bottom half is given over to the cross of these gametes. Individuals marked in bright red are missing a chromosome or have 4 copies -For our hypothetical situation we will say that this is a fatal inheritance and the zygote is spontaneously aborted every time. Individuals in dark red have a monosomy of one of the chromosomes (meaning only one copy). Since our hypothetical situation is taking place in a "natural" society with no modern technology, these individuals will be born (though a high percent of spontaneous abortions occur) but have an extremely low fitness and will die off long before reproductive age. Individuals in purple have a trisomy and suffer the same consequences as individuals with monosomies (lots of spontaneous abortions and killed off before reproductive age). Individuals in bright green all have the equivalent of two 21st and two 14th chromosomes, that is they are "normal". All but one combination in bright green have 45 chromosomes (like the parents) -While one combination has a true 14/14 21/21 genotype. All of these individuals are normal. Finally, the yellow -The real interesting one, has all the genetic information as an individuals with two 14s and two 21s but has only a total of 44 chromosomes.

Boy that is interesting! So now in our hypothetical population where the incidence of carriers increases we have lots of offspring with 45 chromosomes, a few which end up back at 46 and some that have 44. So when these individuals with 44 chromosomes meet, and produce offspring they inherit from their parents a chromosome N and themselves have only 44 chromosomes. Thus we have gone from 46 to 44 chromosomes.

So what happens if the 44 chromosome individuals out-compete the 46 chromosome individuals? A new species? A new branch to the lineage? Evolution?

Now I am sure you are saying, "Whoa, Whoa Copa....That is a whole lot of 'what ifs' and 'hypothetical'". And I say I know! Winning the lottery is also a big what-if, a big hypothetical, but the lottery is a process and when viewed as such it is inevitable that someone is going to win (Compliments to Aquatus for that analogy ). Just like this situation. In fact, we know something along these lines happened once upon a time to a human population -Unlike our closes extant relatives, the rest of the great apes (with 48 chromosomes), we have 46. In our ancestors, 2 chromosomes fused and this chromosomal 'anomaly' floated around the population, until some selective advantage arose for the fused chromosomes and resulted in individuals with 46 instead of 47 or 48 chromosomes. Isn't science cool?

Anyway Yeti, I have run out of time right now (I got sidetracked on Robertsonian translocations and the far reaching outcomes ) so don't have time to go over other mechanisms that refute your authors poor science -But believe me, there are more. If you are interested in them then PM me or start a new topic on translocations in the appropriate section of the forum (PM me and let me know if you do). Hopefully at this point in all the discussions we have had, you will start to appreciate the vast amounts of knowledge out there to be learned and maybe start checking up on your 'sources' before you take such things to heart. It is easy to tell half-truths and no truths to make something sound scientific so that it supports one's own worldview, such as this author has done. Anyway, hope you have learned something and are not put-off by all that posted above.

~Copasetic

[Copasetic]

Is the fixation of a chromosomal aberration pure chance?

To more directly answer your question though; I would say no.

Chance or "random" in science has a very specific meaning.

The fixation of a chromosome by natural selection, sexual selection, artificial selection etc, is not random.

[Neognosis]

That's way too complicated. I say Jesus makes the chromosomes get fixed.

[antonT]

To more directly answer your question though; I would say no.

Chance or "random" in science has a very specific meaning.

The fixation of a chromosome by natural selection, sexual selection, artificial selection etc, is not random.

Many thanks for you detailed and enlightening reply Copasetic. I have always been taught that chromosome mutations are mostly deleterious and at best neutral. I still fail to see the advantage and if there is no advantage then the only way it can get fixed in a population is via genetic drift which surely is pure chance isnt it?

[Copasetic]

Many thanks for you detailed and enlightening reply Copasetic. I have always been taught that chromosome mutations are mostly deleterious and at best neutral. I still fail to see the advantage and if there is no advantage then the only way it can get fixed in a population is via genetic drift which surely is pure chance isnt it?

Its important to understand that a 'chromosome mutation' is not the same thing as a mutation which may happen in or too a single gene. While its common to just lump all mutations together as "mutation" they are most certainly different things, as are their outcomes.

Certainly changing chromosomes, which contain lots of genes and their regulatory regions is often deleterious. Because the shear scale of what is being changed. However, as I pointed out in the posts above, this is not always the case. In fact, its very often not the case. You've probably met someone with an "abnormal" karyotype, but never realized it.

How this number of different chromosomes becomes fixed in the population, doesn't necessarily work the same way as a specific allele would become fixed. Which I think is causing some confusion.

Let's look at the example above for a moment to help clarify this. Where we have a population where 45 chromosome individuals are very frequent. In this population where 45 chromosome individuals meet and reproduce most combinations of (as per the crosses above) chromosomes result in what we termed as fatal inheritances. Others still resulted in an individuals with a drastic loss to fitness. However, some of them (44) result in offspring which have no loss to genetic information. So the number of 44 chromosome individuals increases, not necessarily because they are "better', but because the other outcomes result in spontaneous abortions or offspring who never make it to reproductive age.

Reproductive barriers are what result in stable population of these individuals. The individuals with 44 cannot produce offspring with ancestral karyotypes (46) and have reduced abilities to produce viable offspring with 45 chromosome individuals.

So eventually we get 2 populations, both 'visually' identical to each other, however distinct because of their lack of interbreeding.

A couple things can happen from here.

First, if these two populations go on as is, they have achieved reproductive isolation. The hallmark to differentiation in evolution. By no longer sharing genes between the populations, they accumulate different changes to their genomes. Over time, these small changes are what create very different "looking" populations or ultimately species.

Secondly, the new population could displace the ancestral population from its ecological niche, resulting in replacement and extinction of the ancestral karyotype. If an advantageous mutation arose in the daughter population, which allowed it to out compete the ancestral one then things proceed as normal. The only difference between this and a more conventional scenario is a daughter species with a 'new' number of chromosomes.

Edit: Reading your question again, I think you might be confused about genetic drift. Which applies to the fixation of alleles within a population. Genetic drift works by chance, in contrast to selection.

You are correct in saying that such things could be considered neutral from a fitness stand point. Like in the example, the 44 chromosome individuals which has no loss to their heritable information. This is effectively, neutral, in the cost-benefit game of evolution. What maintains this though, is reproductive barriers -Which evolution can then act upon the population after the reproductive barriers get their say.

Edited February 18, 2009 by Copasetic

[Copasetic]

That's way too complicated. I say Jesus makes the chromosomes get fixed.

There's always that too....

[antonT]

Its important to understand that a 'chromosome mutation' is not the same thing as a mutation which may happen in or too a single gene. While its common to just lump all mutations together as "mutation" they are most certainly different things, as are their outcomes.

Certainly changing chromosomes, which contain lots of genes and their regulatory regions is often deleterious. Because the shear scale of what is being changed. However, as I pointed out in the posts above, this is not always the case. In fact, its very often not the case. You've probably met someone with an "abnormal" karyotype, but never realized it.

How this number of different chromosomes becomes fixed in the population, doesn't necessarily work the same way as a specific allele would become fixed. Which I think is causing some confusion.

Let's look at the example above for a moment to help clarify this. Where we have a population where 45 chromosome individuals are very frequent. In this population where 45 chromosome individuals meet and reproduce most combinations of (as per the crosses above) chromosomes result in what we termed as fatal inheritances. Others still resulted in an individuals with a drastic loss to fitness. However, some of them (44) result in offspring which have no loss to genetic information. So the number of 44 chromosome individuals increases, not necessarily because they are "better', but because the other outcomes result in spontaneous abortions or offspring who never make it to reproductive age.

Reproductive barriers are what result in stable population of these individuals. The individuals with 44 cannot produce offspring with ancestral karyotypes (46) and have reduced abilities to produce viable offspring with 45 chromosome individuals.

So eventually we get 2 populations, both 'visually' identical to each other, however distinct because of their lack of interbreeding.

A couple things can happen from here.

First, if these two populations go on as is, they have achieved reproductive isolation. The hallmark to differentiation in evolution. By no longer sharing genes between the populations, they accumulate different changes to their genomes. Over time, these small changes are what create very different "looking" populations or ultimately species.

Secondly, the new population could displace the ancestral population from its ecological niche, resulting in replacement and extinction of the ancestral karyotype. If an advantageous mutation arose in the daughter population, which allowed it to out compete the ancestral one then things proceed as normal. The only difference between this and a more conventional scenario is a daughter species with a 'new' number of chromosomes.

Edit: Reading your question again, I think you might be confused about genetic drift. Which applies to the fixation of alleles within a population. Genetic drift works by chance, in contrast to selection.

You are correct in saying that such things could be considered neutral from a fitness stand point. Like in the example, the 44 chromosome individuals which has no loss to their heritable information. This is effectively, neutral, in the cost-benefit game of evolution. What maintains this though, is reproductive barriers -Which evolution can then act upon the population after the reproductive barriers get their say.

This will take sometime to absord - thanks. In the meantime I am in a discussion as to whether genetic incompatibility can result soley from gene/allele mutations. I maintain that a significant chromosomal abnormality must occur before gametes become incompatible. As long as the chromosomes line up and their architrcture is compatible is what is important and not what they contain. Can you confirm this? Hope to meet with you again!

[Copasetic]

This will take sometime to absord - thanks. In the meantime I am in a discussion as to whether genetic incompatibility can result soley from gene/allele mutations.

Certainly. Say for example, an embryo received two nonfunctional copies of fetal hemoglobin. This would certainly not work the production of a fetus and result in an abortion of the offspring.

The thing to remember is that the redundancy of our genomes and they way they are structured (mostly given over to noncoding regions) aids in protecting us from this.

I maintain that a significant chromosomal abnormality must occur before gametes become incompatible.

I am not sure what you mean here could you elaborate?

As long as the chromosomes line up and their architrcture is compatible is what is important and not what they contain. Can you confirm this? Hope to meet with you again!

This is kind of backwards. Chromosomes don't necessarily need to 'line up' -Whats important is that the offspring is given a genetic compliment which allows all the necessary functions to be carried out.

When we say that an individual has a 'balanced translocation' -We don't necessarily mean balanced number of chromosomes, rather balanced amount of genetic information. These individuals (although many have different number of chromosomes or 'abnormal' karyotypes) still have the necessary genetic information and often have no health problems associated with the translocation.

In general though, and what you will learn through most of your classes in biology, is that uneven number of chromosomes or mismashed chromosome structure is going to result in the abortion of the fetus. And this is certainly true as general rule, however not as a 'law" of biology. If you spend some time at genetic counseling/fertility help forums you find many individuals with balanced translocations -Who, except for their chromosomal 'abnormality' are perfectly normal and healthy.

I hope that answers your question, if not let me know and maybe I can clarify.

[antonT]

<I am not sure what you mean here could you elaborate? >

A person I am debating evolution/creation with maintains that hybrid infertility and breakdown (genetic incompatibility) is the mechanism that prevents macroevolution and hence evolution. He says that evolution is not possible because macroevolution requires total genetic incompatibility between two organisms of a same species and that this cannot be achieved by ordinary gene mutations and can only happen through a significant chromosomal event (mutation) which, being either deleterious or neutral would stand no chance of getting fixed in a population since there can be no advantage.

This infers that it is chromosomal aberrations (mutations) and not gene mutations at say general loci which are responsible for the diversity of life and that as there is no way for a chromosomal mutation to get fixed due to lack of advantage this must show that God was responsible for the creation of distinct species.

I say that the significant chromosomal abnormalities (mutations) required to create genetic incompatibility and hence the evolution of distinct species achieved fixation via genetic drift which is not a very satisfactory argument for evolution.

Is it really impossible for gene mutations alone (without a significant chromosomal event) to produce a new distinct species which is completely genetically incompatible with its precursor species?

Regards antonT

[Guyver]

This thread should be moved to the Science forum - it's doesnt' have anything to do with spirituality or skepticism.

[Copasetic]

Well the first thing to understand is the concept of species -Which is a man made concept. Species aren't static natural laws, rather dynamic populations. It may help to read This on species concepts.

A person I am debating evolution/creation with maintains that hybrid infertility and breakdown (genetic incompatibility) is the mechanism that prevents macroevolution and hence evolution. He says that evolution is not possible because macroevolution requires total genetic incompatibility between two organisms of a same species and that this cannot be achieved by ordinary gene mutations and can only happen through a significant chromosomal event (mutation) which, being either deleterious or neutral would stand no chance of getting fixed in a population since there can be no advantage.

This is untrue. Reproductive isolation can and does happen by many methods.

Speciation is the result of reproductive isolation, where a population becomes subdivided and gene sharing is stopped. First let's take a moment to understand what he is arguing against. His argument is not against macroevolution, per say, rather cladogenesis, or the "branching" of evolutionary lineages. Without which, life wouldn't be a web (tree), but rather a straight line.

The key to a population of organisms not branching off into new species, genus etc is gene flow. And isolation mechanisms limit or cut off this gene flow, such that over time the population becomes divide and subject to different (even if slightly) evolutionary pressures.

So these physical mechanisms come in two flavors:

Prezygotic Barriers and Postzygotic Barriers

Let's run some of them down to make sure you understand them.

Prezygotic Barriers (premating): prevent mating between populations and is facilitated by positive assortative mating. We can have multiple ways which these premating barriers happen.

Ecological isolation - potential partners never meet.

Temporal isolation - potential partners breed at different times.

Habitat (geographic) isolation - potential partners are spatially segregated.

Lack of interest - Some behavioral or pheromone signal prevent interest from males in females or vise verse.

Its important to understand that while all these potential partners maybe able to produce offspring (viable), they are not interbreeding and their populations are not sharing hereditary information.

Postzygotic Barriers: Mating and/or gamete transfer occurs, but zygotes are not formed. Again, there are multiple ways this can occur.

We can subdivide these into two types: Postmating, prezygotic barriers and Postzygotic.

Postmating, prezygotic barriers:

Mechanical isolation - Sexual reproductive organs ofter adhere to the "lock and key" conformity found elsewhere in biology. In other words a certain copulatory organ may not fit into another.

Copulatory behavior isolation - Some organisms have specific behaviors in which they engage during mating, the lack of these or presence of these may discourage mating.

Gametic isolation - Sperm and egg don't recognize each other.

Postzygotic barriers: Fertilization takes place but may not result in successful offspring.

Extrinsic factors like; Ecological inviability or Behavioral sterility.

Intrinsic factors like; Hybrid inviability or hybrid sterility.

This infers that it is chromosomal aberrations (mutations) and not gene mutations at say general loci which are responsible for the diversity of life and that as there is no way for a chromosomal mutation to get fixed due to lack of advantage this must show that God was responsible for the creation of distinct species.

As provided in the example above from my first two posts, it is possible to add/reduce the number of chromosomes in a population -Which can certainly lead to speciation events. Speciation (cladogenesis) is not the purpose of evolution. Rather, it is a byproduct of these other mechanisms of isolation that achieve cladogenesis. In time, we have the gradual accumulation of changes which leads to vastly different species.

We also have Richard Goldschmidt's "hopeful monsters". Which give instantaneous or near instantaneous speciation events. Where we have things like autopolyploidy or allopolyploidy.

It may also be helpful for both of you to look over Allopatric speciation, Sympatric speciation and Parapatric speciation. If you have any questions about those I would be glad to answer via pm or make a topic in the science section (pm me if you do so I don't miss it).

I say that the significant chromosomal abnormalities (mutations) required to create genetic incompatibility and hence the evolution of distinct species achieved fixation via genetic drift which is not a very satisfactory argument for evolution.

I don't think its wise to think of genetic drift working like this. The mutations which initially separate populations don't need to be large, nor even adaptive. Selection maintains the barriers between two populations and if the mutations each subset accumulates increases fitness their fitness, then they will be favored over prior conditions. Creating a sort of cycle, where selection feeds the barriers and the barriers feed the accumulation of changes.

Is it really impossible for gene mutations alone (without a significant chromosomal event) to produce a new distinct species which is completely genetically incompatible with its precursor species?

No its not impossible.

Also again, as a recommendation, read the link by JBL Mallet on the species problem.

Hope that helps,

[antonT]

This thread should be moved to the Science forum - it's doesnt' have anything to do with spirituality or skepticism

Are you sure? Isn't the evolution/creation debate skepticism or spirituality?

[raphnix]

That's way too complicated. I say Jesus makes the chromosomes get fixed.

LOL

You're using that reason just to avoid studying the scientific proof. I can't blame you if you're too lazy to read Copasetic post.

[antonT]

Well the first thing to understand is the concept of species -Which is a man made concept. Species aren't static natural laws, rather dynamic populations. It may help to read This on species concepts.

I must stress that I am agnostic and am only playing devil's advocate. Creationists maintain that biology's 13+ definitions of species (wikipedia) make a mockery of debate terms and that subsequently the creationist's single definition of "kind"(species that can interbreed and produce a viable zygote irrespective of hybrid fertility breakdown) should be adopted instead.

This is untrue. Reproductive isolation can and does happen by many methods[

.

It is claimed that reproductive isolation only serves Darwinian sub-speciation and not macro-speciation (evolution of one distinct species to another) which can only be achieved by a significant chromosome event (mutation)

The key to a population of organisms not branching off into new species, genus etc is gene flow. And isolation mechanisms limit or cut off this gene flow, such that over time the population becomes divide and subject to different (even if slightly) evolutionary pressures.

So these physical mechanisms come in two flavors:

Prezygotic Barriers and Postzygotic Barriers

Creationists claim that pre-mating isolating mechanisms are irrelevent if species can still interbreed if put to the artificial insemination test. Just because they do not interbreed does not mean that they cannot. The hybrid breakdown mechanism (reduction of fertility to the point of infertility) does not need isolation - only a significant chromosomal event (mutation)

In time, we have the gradual accumulation of changes which leads to vastly different species.

Here we come to the crux of the matter. Creationists claim that organisms can sub-speciate (adapt and drift with isolation) for millions of years and still not achieve genetic(gametic) incompatability. They claim the only true speciation is not caused by gene mutations but by relative differences in karyotype which cause difficulties in chromosomal crossover representing the beginning of genetic decoupling which afterall is what true evolution is about.( in the eyes of the layman)

Thus I am in a bit of a quandry for I cannot find any benefit at all being derived from chromosomal mutations which subsequently eliminates natural selection as the principle driver for genetic evolution ( cessation of interbreeding). Add this fact to the complete illogicality of chromosome numbers and one does not wonder at the layman's reluctance to embrace wholeheartedly the theory of evolution.

Your thoughts?

[Guyver]

Are you sure? Isn't the evolution/creation debate skepticism or spirituality?

OK fine. But you didn't say that until post #11.

[Copasetic]

I must stress that I am agnostic and am only playing devil's advocate. Creationists maintain that biology's 13+ definitions of species (wikipedia) make a mockery of debate terms and that subsequently the creationist's single definition of "kind"(species that can interbreed and produce a viable zygote irrespective of hybrid fertility breakdown) should be adopted instead.

Whether or not they maintain this, has no bearing on the actual matter at hand. Species are not real things, they are very much man made constructs to make classification and discussion easier. "Kind" has no relevance to science, as its definition (as you are using it here) doesn't produce any useful or explanatory information regarding life on earth.

Similarly, "kind" does not account for genetic relatedness, nor does it address asexual organisms.

Also, can you source your definition of kind? There is no agreement by creationists of what a biblical "kind" is, which kind of makes the attack on the many species concepts illogical. Creationists can't agree on a definition of kind, for the same reason that we have so many species concepts. That being the division of 'species' are not real.

It is claimed that reproductive isolation only serves Darwinian sub-speciation and not macro-speciation (evolution of one distinct species to another) which can only be achieved by a significant chromosome event (mutation)

Claiming something and the reality of something, need not always agree. For this to be true, creationists would need a mechanism(s) which stops the processes of selection acting upon environmental change for two populations. Once two populations are reproductively isolated they no longer experience the same selective pressures and thus have their own unique lineages after the branching.

Their argument falls apart when looking at chromosome number as well.

For instance, the Kit fox (Vulpes macrotis) has 50 chromosomes, while the closely related Red fox (Vulpes vulpes) has 38. While the Fennec fox (Vulpes zerda) has 64 and the Bengal fox (Vulpes bengalensis) has 60.

Similarly, The Raccoon dog has many subspecies ranging in chromosome number of 38, 54, 56 and 57. And even within a subspecies populations differ in their karyotypes. For instance, some of the Chinese Raccoon Dog subspecies populations have 54 Chromosomes (52+XX) while other populations have up too 58 (one population having a karyotype of 52+XX+4B's).

So what does this say of the creationist argument? Are we to believe that God created so many "kinds" of foxes or raccoon dogs? These animals, while differing in their number of chromosomes are often able to produce hybrids as well. What prevents hybridization in the wild, are those premating/prezygotic barriers.

So what do real world animals (not make believe ones) do to the creationist idea of "kind"? How does "kind" approach such collective groups of animals?

It's easy, they don't. This is just another area where "creation science" falls apart.

Creationists claim that pre-mating isolating mechanisms are irrelevent if species can still interbreed if put to the artificial insemination test. Just because they do not interbreed does not mean that they cannot. The hybrid breakdown mechanism (reduction of fertility to the point of infertility) does not need isolation - only a significant chromosomal event (mutation)

Again, creationists are free to claim what they may, however their claims often (very often) come into conflict with reality.

As I pointed out above, the 'glue' of a population is its ability to share genes across the group. Without this ability a population will be subdivided and subject to differential selective pressures.

It doesn't really matter if we can artificially force two different lineages to breed -What matters is are they doing this in nature? Because if they are not, then there is no way for gene flow to keep the groups 'similar'.

Here we come to the crux of the matter. Creationists claim that organisms can sub-speciate (adapt and drift with isolation) for millions of years and still not achieve genetic(gametic) incompatability.

Lineages can branch off for millions of years and not achieve gametic incompatibility. Zebra's have between 32 and 46 chromosomes depending on the species. Horses have 64 and donkeys have 62, yet all of these animals are capable of forced breeding and producing offspring.

This also creates lots of problems for the creationist argument. On the one hand, they can claim that Zebra, donkeys and horses are all one "kind" of animal -Which then begs the question of how the chromosome number became different. To answer this, they either rely on evolution or need to introduce some new mechanism by which it happens.

Alternatively they could claim that Horses, donkeys and zebra are all different kinds of animals. I think this is even worse for their argument, because such hybrids would then constitute new "kinds" which pretty effectively shatters their arguments.

They claim the only true speciation is not caused by gene mutations but by relative differences in karyotype which cause difficulties in chromosomal crossover representing the beginning of genetic decoupling which afterall is what true evolution is about.( in the eyes of the layman)

If true speciation is caused only by "relative differences in karyotype", Then I will be very interested to hear your (playing devil's advocate) or their explanation of the Zebra/horse/donkey, foxes and raccoon dogs.

Which are either:

1. Separate 'kinds', which hybridize to create new 'kinds'.

2. Are the same 'kind' which speciate into new and distinct species ('macroevolution').

Thus I am in a bit of a quandry for I cannot find any benefit at all being derived from chromosomal mutations which subsequently eliminates natural selection as the principle driver for genetic evolution ( cessation of interbreeding).

I am not sure I understand your quandry anton. Why should a chromosomal mutation, such as a translocation, need to eliminate natural selection?

I think the problem here Anton, is whoever you are debating with (and possibly you) have the "A little information is a bad thing"-syndrome going on here.

Add this fact to the complete illogicality of chromosome numbers and one does not wonder at the layman's reluctance to embrace wholeheartedly the theory of evolution.

Your thoughts?

Sure, if you just look at chromosome number as a crapshoot then I am sure they are confusing. Trying to understand chromosome numbers in light of either creation science or a high school education in biology, is no doubt bound to leave one muddled.

However, as Dobzhansky said; "Nothing in Biology Makes Sense Except in the Light of Evolution."

The "illogicality" of chromosomes and their numbers disappears in light of evolutionary biology.

Edited February 19, 2009 by Copasetic

[antonT]

Whether or not they maintain this, has no bearing on the actual matter at hand. Species are not real things, they are very much man made constructs to make classification and discussion easier. "Kind" has no relevance to science, as its definition (as you are using it here) doesn't produce any useful or explanatory information regarding life on earth.

Similarly, "kind" does not account for genetic relatedness, nor does it address asexual organisms.

Also, can you source your definition of kind? There is no agreement by creationists of what a biblical "kind" is, which kind of makes the attack on the many species concepts illogical. Creationists can't agree on a definition of kind, for the same reason that we have so many species concepts. That being the division of 'species' are not real.

I am the source for the above definition of kind. It represents a perception gleaned from an adolescence spent as a devout Christian before becoming an agnostic. It would be difficult to discuss the topic without some sort of consensus on definitions. I would be happy to use the biological species concept of "species" if you wish as it virtually has the same meaning as the biblical word kind.

In this instance this would represent "spirituality" accommodating "skepticism" on skepticism's terms in order progess matters. It also demonstrates that spirituality is pretty confident of its stance in these matters.

Claiming something and the reality of something, need not always agree. For this to be true, creationists would need a mechanism(s) which stops the processes of selection acting upon environmental change for two populations. Once two populations are reproductively isolated they no longer experience the same selective pressures and thus have their own unique lineages after the branching.

Their argument falls apart when looking at chromosome number as well.

For instance, the Kit fox (Vulpes macrotis) has 50 chromosomes, while the closely related Red fox (Vulpes vulpes) has 38. While the Fennec fox (Vulpes zerda) has 64 and the Bengal fox (Vulpes bengalensis) has 60.

Similarly, The Raccoon dog has many subspecies ranging in chromosome number of 38, 54, 56 and 57. And even within a subspecies populations differ in their karyotypes. For instance, some of the Chinese Raccoon Dog subspecies populations have 54 Chromosomes (52+XX) while other populations have up too 58 (one population having a karyotype of 52+XX+4B's).

So what does this say of the creationist argument? Are we to believe that God created so many "kinds" of foxes or raccoon dogs? These animals, while differing in their number of chromosomes are often able to produce hybrids as well. What prevents hybridization in the wild, are those premating/prezygotic barriers.

So what do real world animals (not make believe ones) do to the creationist idea of "kind"? How does "kind" approach such collective groups of animals?

It's easy, they don't. This is just another area where "creation science" falls apart.

Creationists don't see any problem with the above. As far as I know everyone accepts adaptation and that adaptation happens in sub-species. The chromosome problem is a problem for evolutionists because it demonstrates that the crossing of the Ts and dotting of the Is for evolution is indeed "genetic incompatibility", incompatibility without which to quote Darwin himself

life would be a confusion of organic forms:

"" The view generally entertained by naturalists is that species, when intercrossed, have been specially endowed with the quality of sterility, in order to prevent the confusion of all organic forms. . . . On the theory of natural selection the case is especially important, inasmuch as the sterility of hybrids could not possibly be of an advantage to them, and therefore could not have been acquired by the continued preservation of successive profitable degrees of sterility."

The fact that a significant chromosomal mutation or problem must first cause genetic incompatibility before a species can be deemed a separate distinct species and that the fact that there is no advantage to chromosomal mutations together with the problem of their fixation in a population begs the question as to whether indeed macroevolution can happen at all.

Again, creationists are free to claim what they may, however their claims often (very often) come into conflict with reality.

As I pointed out above, the 'glue' of a population is its ability to share genes across the group. Without this ability a population will be subdivided and subject to differential selective pressures.

It doesn't really matter if we can artificially force two different lineages to breed -What matters is are they doing this in nature? Because if they are not, then there is no way for gene flow to keep the groups 'similar'.

Lineages can branch off for millions of years and not achieve gametic incompatibility. Zebra's have between 32 and 46 chromosomes depending on the species. Horses have 64 and donkeys have 62, yet all of these animals are capable of forced breeding and producing offspring.

This also creates lots of problems for the creationist argument. On the one hand, they can claim that Zebra, donkeys and horses are all one "kind" of animal -Which then begs the question of how the chromosome number became different. To answer this, they either rely on evolution or need to introduce some new mechanism by which it happens.

Alternatively they could claim that Horses, donkeys and zebra are all different kinds of animals. I think this is even worse for their argument, because such hybrids would then constitute new "kinds" which pretty effectively shatters their arguments.

I don't see why a different number of chromosomes should prevent organism being of the same kind. It simply means that in spite of different architecture the genetics are still compatible.

If true speciation is caused only by "relative differences in karyotype", Then I will be very interested to hear your (playing devil's advocate) or their explanation of the Zebra/horse/donkey, foxes and raccoon dogs.

Which are either:

1. Separate 'kinds', which hybridize to create new 'kinds'.

2. Are the same 'kind' which speciate into new and distinct species ('macroevolution').

They are of the same "kind" without doubt. Relative difference in karyotype are indisputedly the cause of hybrid breakdown and hybrid infertility. Creationists would say that these two mechanisms are God's mechanisms, especially created to ensure the integrity of distinct species. Everything seems to fit in so neatly.

I am not sure I understand your quandry anton. Why should a chromosomal mutation, such as a translocation, need to eliminate natural selection?

I think the problem here Anton, is whoever you are debating with (and possibly you) have the "A little information is a bad thing"-syndrome going on here.

Sure, if you just look at chromosome number as a crapshoot then I am sure they are confusing. Trying to understand chromosome numbers in light of either creation science or a high school education in biology, is no doubt bound to leave one muddled.

However, as Dobzhansky said; "Nothing in Biology Makes Sense Except in the Light of Evolution."

The "illogicality" of chromosomes and their numbers disappears in light of evolutionary biology.

Natural selection ( survival of the fittest), as the driver of adaptation would be relegated to sub-speciation if the essence of evolution "genetic incompatibility" happens through pure chance and luck (genetic drift) as looks probable.

As things stand, uncommited layman that I am, I am beginning to think that "Nothing in Biology Makes Sense Except in the Light of Adaptation(sub-speciation) - not Evolution"

The laws of science balance precariously on a tightrope over chaos (Stephen Hawking with license). If this is indeed so then the laws of science have no substantive foundations and everyone knows that an edifice is only as good as its foundations.

It could just be possible that Life, indeed Existence itself be the result of a Miracle!

[Copasetic]

I am the source for the above definition of kind. It represents a perception gleaned from an adolescence spent as a devout Christian before becoming an agnostic. It would be difficult to discuss the topic without some sort of consensus on definitions. I would be happy to use the biological species concept of "species" if you wish as it virtually has the same meaning as the biblical word kind.

In this instance this would represent "spirituality" accommodating "skepticism" on skepticism's terms in order progess matters. It also demonstrates that spirituality is pretty confident of its stance in these matters.

It's important to realize, that using any concept of species (be that kind, biological, recognition, phylogenetic etc) is only a classification built by man to discuss lineages. Whether or not we are talking about 'spirituality accommodating skepticism' or vise versa, makes no difference -Species are not real, tangible things. They are not a fact of nature. It is simply a division of a snapshot in time. Its important to understand that.

Creationists don't see any problem with the above. As far as I know everyone accepts adaptation and that adaptation happens in sub-species. The chromosome problem is a problem for evolutionists because it demonstrates that the crossing of the Ts and dotting of the Is for evolution is indeed "genetic incompatibility", incompatibility without which to quote Darwin himself

life would be a confusion of organic forms:

"" The view generally entertained by naturalists is that species, when intercrossed, have been specially endowed with the quality of sterility, in order to prevent the confusion of all organic forms. . . . On the theory of natural selection the case is especially important, inasmuch as the sterility of hybrids could not possibly be of an advantage to them, and therefore could not have been acquired by the continued preservation of successive profitable degrees of sterility."

First off, its important to remember that while we consider Darwin the father of evolutionary biology and one of the greats amongst biologists, he wrote "On origins of species", without any knowledge of genetics, molecular biology, cell theory etc. While Darwin's works gave future biologists the foundation for evolution by natural selection, his works were neither complete nor totally correct. So now that is out of the way, let's continue.

I know you have said you are playing "Devil's advocate" and you seem to have certainly got into the role. The whole quote mining thing really puts a nice touch on the creationist facade

Let's look somemore on Darwin's chapter on hybrids. Here is the complete summary of the chapter:

First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. The sterility is of all degrees, and is often so slight that the two most careful experimentalists who have ever lived, have come to diametrically opposite conclusions in ranking forms by this test. The sterility is innately variable in individuals of the same species, and is eminently susceptible of favourable and unfavourable conditions. The degree of sterility does not strictly follow systematic affinity, but is governed by several curious and complex laws. It is generally different, and sometimes widely different, in reciprocal crosses between the same two species. It is not always equal in degree in a first cross and in the hybrid produced from this cross.

In the same manner as in grafting trees, the capacity of one species or variety to take on another, is incidental on generally unknown differences in their vegetative systems, so in crossing, the greater or less facility of one species to unite with another, is incidental on unknown differences in their reproductive systems. There is no more reason to think that species have been specially endowed with various degrees of sterility to prevent them crossing and blending in nature, than to think that trees have been specially endowed with various and somewhat analogous degrees of difficulty in being grafted together in order to prevent them becoming inarched in our forests.

The sterility of first crosses between pure species, which have their reproductive systems perfect, seems to depend on several circumstances; in some cases largely on the early death of the embryo. The sterility of hybrids, which have their reproductive systems imperfect, and which have had this system and their whole organisation disturbed by being compounded of two distinct species, seems closely allied to that sterility which so frequently affects pure species, when their natural conditions of life have been disturbed. This view is supported by a parallelism of another kind; -- namely, that the crossing of forms only slightly different is favourable to the vigour and fertility of their offspring; and that slight changes in the conditions of life are apparently favourable to the vigour and fertility of all organic beings. It is not surprising that the degree of difficulty in uniting two species, and the degree of sterility of their hybrid-offspring should generally correspond, though due to distinct causes; for both depend on the amount of difference of some kind between the species which are crossed. Nor is it surprising that the facility of effecting a first cross, the fertility of the hybrids produced, and the capacity of being grafted together -- though this latter capacity evidently depends on widely different circumstances -- should all run, to a certain extent, parallel with the systematic affinity of the forms which are subjected to experiment; for systematic affinity attempts to express all kinds of resemblance between all species.

First crosses between forms known to be varieties, or sufficiently alike to be considered as varieties, and their mongrel offspring, are very generally, but not quite universally, fertile. Nor is this nearly general and perfect fertility surprising, when we remember how liable we are to argue in a circle with respect to varieties in a state of nature; and when we remember that the greater number of varieties have been produced under domestication by the selection of mere external differences, and not of differences in the reproductive system. In all other respects, excluding fertility, there is a close general resemblance between hybrids and mongrels. Finally, then, the facts briefly given in this chapter do not seem to me opposed to, but even rather to support the view, that there is no fundamental distinction between species and varieties.

(My emphasis)

All of this available at the Darwin Digital Library for free.

Darwin was fond of poetically setting up a position contrary to his own, to argue against. All you have done, is paste two of those points together. If you actually read the chapter in Origins you will see that what Darwin is actually arguing is that the 'species' lines are so blurred because of common ancestry and that the vigor of fertile hybrids is favored by natural selection.

This again comes back to something you are not seeming to understand and largely glanced over in one of my previous posts. What keeps evolutionary lineages separate is not 'genetic incompatibility', but rather reproductive isolation. If two populations (for whatever reasons) are not sharing genes, then their accumulations of new alleles will differ from one another. You can call this 'adaptation' all you want, but without introducing a mechanism to limit the accumulation of new alleles you lack the proverbial leg to stand on.

The fact that a significant chromosomal mutation or problem must first cause genetic incompatibility before a species can be deemed a separate distinct species and that the fact that there is no advantage to chromosomal mutations together with the problem of their fixation in a population begs the question as to whether indeed macroevolution can happen at all.

That first part there in bold is simply made up. As I said now numerous times, 'genetic incompatibility' is not the only thing that determines whether a lineage is 'separate and distinct'. There are numerous ways, by which reproductive isolation is achieved.

Please cite credible (as in a journal) references for the second boldface. Contrary to your statements, research and data has shown that 'chromosomal mutations' can and do undergo positive selection. Please check out some of these publications for more information;

1. Bielawski JP, Yang Z. Positive and negative selection in the DAZ gene family. Mol Biol Evol 2001 Apr;18(4):523-9.

2. Malik HS, Henikoff S. Conflict begets complexity: The evolution of centromeres. Curr Opin Genet Dev 2002 Dec;12(6):711-8.

3. Stefansson H, Helgason A, Thorleifsson G, Steinthorsdottir V, Masson G, Barnard J, Baker A, Jonasdottir A, Ingason A, Gudnadottir VG, Desnica N, Hicks A, Gylfason A, Gudbjartsson DF, Jonsdottir GM, Sainz J, Agnarsson K, Birgisdottir B, Ghosh S, Olafsdottir A, Cazier JB, Kristjansson K, Frigge ML, Thorgeirsson TE, Gulcher JR, Kong A, Stefansson K. A common inversion under selection in europeans. Nat Genet 2005 Feb;37(2):129-37.

4. Voight BF, Kudaravalli S, Wen X, Pritchard JK. A map of recent positive selection in the human genome. PLoS Biol 2006 Mar;4(3):e72.

5. Zhang J. Evolution by gene duplication: An update. Trends Ecol Evol June 2003;18(6):292-8.

I don't see why a different number of chromosomes should prevent organism being of the same kind. It simply means that in spite of different architecture the genetics are still compatible.

So let's look at the case of equines. We have all these equines which share a common equine "kind" ancestor. Yet we have various members of the 'kind' with various numbers of chromosomes.

So what, (since the flood) has caused the different number of chromosomes? Also be mindful, that whatever mechanism you introduce, you also need to introduce some type of countenance mechanism which will stop these equines from ever being able to turn into different "kinds".

So we have differential evolution of chromosome number, which undoubted has undergone natural selection at some point. Which defeats the whole purpose of your argument, that 'chromosome mutations' only become fixed by chance.

They are of the same "kind" without doubt. Relative difference in karyotype are indisputedly the cause of hybrid breakdown and hybrid infertility. Creationists would say that these two mechanisms are God's mechanisms, especially created to ensure the integrity of distinct species. Everything seems to fit in so neatly.

Interesting,

So by your definition of kind (species that can interbreed and produce a viable zygote irrespective of hybrid fertility breakdown) then two organisms like the Margay:

and the Oncilla:

constitute two distinct 'kinds' as they are unable to hybridize.

Similarly the clouded leopard would need to be its own distinct kind, as there has never been a sucess in creating hyrbids between it and other memeber of the felids.

Interestingly, the Margray and Oncilla are both able to hybridize with the domestic house cat. Which means, we have the creation of new kinds (since based on your definition of kind Margrays, Oncillas and domestic house cats cannot all be of the same kind).

Natural selection ( survival of the fittest), as the driver of adaptation would be relegated to sub-speciation if the essence of evolution "genetic incompatibility" happens through pure chance and luck (genetic drift) as looks probable.

Firstly, this is a fundamental misunderstanding of natural selection. Do you have children? If so, do you consider yourself the most fit human being alive today? If not then you have survived and reproduced, yet you are not the fittest. Natural selection is more like "survival of the fit enough".

Second, you completely sidestepped the question (as you have done above with other questions); Why should 'chromosomal mutations' need to eliminate natural selection.

This question was directed at your statement:

Thus I am in a bit of a quandry for I cannot find any benefit at all being derived from chromosomal mutations which subsequently eliminates natural selection as the principle driver for genetic evolution ( cessation of interbreeding).

Third, as I have explained now numerous times, "genetic incompatibility" is not the essence of evolution. Could you cite where you are getting this from? The essence of cladogenesis is reproducitve isolation. To which there are numerous mechanims which are capable of producing such isolation.

As things stand, uncommited layman that I am, I am beginning to think that "Nothing in Biology Makes Sense Except in the Light of Adaptation(sub-speciation) - not Evolution"

The laws of science balance precariously on a tightrope over chaos (Stephen Hawking with license). If this is indeed so then the laws of science have no substantive foundations and everyone knows that an edifice is only as good as its foundations.

It could just be possible that Life, indeed Existence itself be the result of a Miracle!

As things stand, I don't think your really the 'uncommitted layman' you claim to be, but that's just a personal opinion

Adaptation is a product of evolution, an emergent property of selection. To claim that selection is only capable of producing adaptations within 'kinds', you need to introduce some mechanism by which genetic diversity over time is limited and stops the creation of greater nested hierarchies.

In case you are confused by what I mean, maybe an example will help.

You claim there are distinct 'kinds' created by god. Such as a bear (though by your definition above there would need to be at least 3 'kinds' of bears, but let's roll with this for arguments sake).

So black bears belong to the kind bear, because they contain traits which undoubtedly group them with bears. However, bears also can lay claim to belonging to the 'kind' Caniformia as they share again, numerous nested traits. Also the order Carnivora, the superorder Laurasiatheria, the infraclass Eutheria, the subclass Theria, the class Mammalia, the superclass Tetrapoda, the infraphylum Gnathostomata, the subphylum Vertebrata, the phylum Chordata, the superphylum Deuterostomia, the subkingdom Eumetazoa, the kingdom Animalia and the domain Eukaryota.

So the question is, why? Why do bears share specific traits with all members of the group Tetrapoda or Chordata or Eutheria? And the answer to that is evolution. What we see, when we study life, is a model consistent with evolution -Not special creation.

How does evolution explain these nestings? By common ancestry and cladogensis.

At one point in life on earth's history there walked the ancestor to the 'kind' Carnivora. All descendents of this ancestor, share some common features. Similarly, there once existed the ancestor of the 'kind' Tetrapoda, who's extant and extinct descendants, again share common features.

How is this possible? Because reproductive isolation ensures the stoppage of gene flow between two populations, these populations will go on accumulating their own distinct changes as the result of varying selective pressures acting upon the gene pool of the lineage. Each, lineage then will share some traits with the common ancestral population, but have their own distinct changes as well.

Your argument is, at some point this has to stop. That at some point, some mechanism stops changes from occuring such that we could further subdivide "kinds" by these nested sets. Please introduce this mechanism and how it stops the accumulation of traits which creates such nested sets.

Edited February 20, 2009 by Copasetic

[antonT]

It's important to realize, that using any concept of species (be that kind, biological, recognition, phylogenetic etc) is only a classification built by man to discuss lineages. Whether or not we are talking about 'spirituality accommodating skepticism' or vise versa, makes no difference -Species are not real, tangible things. They are not a fact of nature. It is simply a division of a snapshot in time. Its important to understand that.

I believe that kinds are a fact of nature. There is a natural morphological and genetic difference between say a seagull and a fox which cannot be denied.

Please cite credible (as in a journal) references for the second boldface. Contrary to your statements, research and data has shown that 'chromosomal mutations' can and do undergo positive selection. Please check out some of these publications for more information;

1. Bielawski JP, Yang Z. Positive and negative selection in the DAZ gene family. Mol Biol Evol 2001 Apr;18(4):523-9.

2. Malik HS, Henikoff S. Conflict begets complexity: The evolution of centromeres. Curr Opin Genet Dev 2002 Dec;12(6):711-8.

3. Stefansson H, Helgason A, Thorleifsson G, Steinthorsdottir V, Masson G, Barnard J, Baker A, Jonasdottir A, Ingason A, Gudnadottir VG, Desnica N, Hicks A, Gylfason A, Gudbjartsson DF, Jonsdottir GM, Sainz J, Agnarsson K, Birgisdottir B, Ghosh S, Olafsdottir A, Cazier JB, Kristjansson K, Frigge ML, Thorgeirsson TE, Gulcher JR, Kong A, Stefansson K. A common inversion under selection in europeans. Nat Genet 2005 Feb;37(2):129-37.

4. Voight BF, Kudaravalli S, Wen X, Pritchard JK. A map of recent positive selection in the human genome. PLoS Biol 2006 Mar;4(3):e72.

5. Zhang J. Evolution by gene duplication: An update. Trends Ecol Evol June 2003;18(6):292-8.

There is nothing in the above abstracts that changes my opinion that chromosomal mutations are chaotic to the point of being random or that they do not posess any advantage that would be visible to natural selection. With regard to the paper "A common inversion under selection in europeans". I see nothing in the abstract to change my opinion. Iceland has a minute population and besides, being more fertile than fertile is absolutely meaningless.

http://en.wikipedia.org/wiki/Haplogroup

So let's look at the case of equines. We have all these equines which share a common equine "kind" ancestor. Yet we have various members of the 'kind' with various numbers of chromosomes.

So what, (since the flood) has caused the different number of chromosomes? Also be mindful, that whatever mechanism you introduce, you also need to introduce some type of countenance mechanism which will stop these equines from ever being able to turn into different "kinds".

So we have differential evolution of chromosome number, which undoubted has undergone natural selection at some point. Which defeats the whole purpose of your argument, that 'chromosome mutations' only become fixed by chance.

Having dealt with the chance issue, the horse issue is dealt with accordingly: http://www.truthinscience.org.uk/site/content/view/55/65/

So by your definition of kind (species that can interbreed and produce a viable zygote irrespective of hybrid fertility breakdown) then two organisms like the Margay:

and the Oncilla:

constitute two distinct 'kinds' as they are unable to hybridize.

Similarly the clouded leopard would need to be its own distinct kind, as there has never been a sucess in creating hyrbids between it and other memeber of the felids.

Interestingly, the Margray and Oncilla are both able to hybridize with the domestic house cat. Which means, we have the creation of new kinds (since based on your definition of kind Margrays, Oncillas and domestic house cats cannot all be of the same kind).

To my knowledge artificial insemination trials have yet to be conducted on these two organisms.

Firstly, this is a fundamental misunderstanding of natural selection. Do you have children? If so, do you consider yourself the most fit human being alive today? If not then you have survived and reproduced, yet you are not the fittest. Natural selection is more like "survival of the fit enough".

Second, you completely sidestepped the question (as you have done above with other questions); Why should 'chromosomal mutations' need to eliminate natural selection.

I have used the term "survival of the fittest" loosely to donate "advantage" that's all. Chromosomal mutations marginalise natural selection to a sub-speciation role

The title of the book "Origin of species by means of natural selection" should be replaced by "Origin of species by means of genetic drift". Darwin mistakenly believed that Darwinian speciation (sub-speciation) was principally driven by natural selection when in fact genetic drift is the principle player both in sub-speciation and genetic decoupling.

Thus chromosomal mutation via genetic drift replaces natural selection as the predominant driver of evolution . I realise there was no such thing as genetic drift in Darwins day.

Adaptation is a product of evolution, an emergent property of selection. To claim that selection is only capable of producing adaptations within 'kinds', you need to introduce some mechanism by which genetic diversity over time is limited and stops the creation of greater nested hierarchies.

In case you are confused by what I mean, maybe an example will help.

You claim there are distinct 'kinds' created by god. Such as a bear (though by your definition above there would need to be at least 3 'kinds' of bears, but let's roll with this for arguments sake).

So black bears belong to the kind bear, because they contain traits which undoubtedly group them with bears. However, bears also can lay claim to belonging to the 'kind' Caniformia as they share again, numerous nested traits. Also the order Carnivora, the superorder Laurasiatheria, the infraclass Eutheria, the subclass Theria, the class Mammalia, the superclass Tetrapoda, the infraphylum Gnathostomata, the subphylum Vertebrata, the phylum Chordata, the superphylum Deuterostomia, the subkingdom Eumetazoa, the kingdom Animalia and the domain Eukaryota.

So the question is, why? Why do bears share specific traits with all members of the group Tetrapoda or Chordata or Eutheria? And the answer to that is evolution. What we see, when we study life, is a model consistent with evolution -Not special creation.

How does evolution explain these nestings? By common ancestry and cladogensis.

At one point in life on earth's history there walked the ancestor to the 'kind' Carnivora. All descendents of this ancestor, share some common features. Similarly, there once existed the ancestor of the 'kind' Tetrapoda, who's extant and extinct descendants, again share common features.

How is this possible? Because reproductive isolation ensures the stoppage of gene flow between two populations, these populations will go on accumulating their own distinct changes as the result of varying selective pressures acting upon the gene pool of the lineage. Each, lineage then will share some traits with the common ancestral population, but have their own distinct changes as well.

Your argument is, at some point this has to stop. That at some point, some mechanism stops changes from occuring such that we could further subdivide "kinds" by these nested sets. Please introduce this mechanism and how it stops the accumulation of traits which creates such nested sets.

This argument is equally attributable to a common designer!

The laws of science are based on randomness(chaos). Abiogenises, the spontaneous generation of life from chemicals would have to occur randomly (chaotically) as there would be no reproduction to invoke "survival of the fittest". True Evolution (chromosome mutation) is a random (chaotic ) process. These three fundamentals have chaos (randomness) at their roots. Chaotic fundamentals suggest some sort of magic or miracle; a miracle requires a miracle worker and that miracle worker could be a God.......

[Copasetic]

I believe that kinds are a fact of nature. There is a natural morphological and genetic difference between say a seagull and a fox which cannot be denied.

Your belief is irrelevant Anton, and has no bearing on reality.

While seagulls and foxes certainly have differences, they also share similarities which 'cannot be denied'. So much so, that we could even say they belong to the same 'kind'.

They both have 4 appendages, similar frontal and rear portion lengths of the skull, more posterior orbital vacuities, a relatively larger pectoral girdle etc. So clearly, both gulls and foxes belong to the kind Tetrapoda. The kind Tetrapoda shares these characteristics to the exclusion of all others.

They also both have distinct somatic/germ cell layers, embryos that go through gastrulation, specialized true tissues, etc. So then they both belong to the kind Eumetazoa.

We could also say that they belong to the kind Vertebrate, or Chordata, etc.

That there are nested sets of traits is a fact of nature, and this is due to evolution. Looking at life on earth we see exactly what we would expect to see if life on earth had evolved. Unfortunately for your argument, what we don't see is evidence consistent with many 'kinds' of animals being specially created and evolving into 'subkinds'.

Of course, if you were really playing devil's advocate (which at this point I don't think you are, but that's my opinion) you could argue that God the omnipotent simply created the earth and life on it to appear as if evolution occurred.

There is nothing in the above abstracts that changes my opinion that chromosomal mutations are chaotic to the point of being random or that they do not posess any advantage that would be visible to natural selection. With regard to the paper "A common inversion under selection in europeans". I see nothing in the abstract to change my opinion. Iceland has a minute population and besides, being more fertile than fertile is absolutely meaningless.

http://en.wikipedia.org/wiki/Haplogroup

Here's some free advice, you might actually need to read a paper or two.....You know, to see for yourself and all. At this point, I am going to go out on a limb and guess that you have no access to scientific literature (though for a dollar-fifty in late charges, most people can get access to them at a public library)

So lets look at some of the results of the Iceland study.

To determine whether positive selection is presently acting on H2 chromosomes, we genotyped 29,137 Icelanders, 16,959 women and 12,178 men, born between 1925 and 1965, with the marker DG17S142. In Icelanders (and in the Utah sample), the alleles 404 and 406 of this marker are perfect surrogates for the H2 lineage. We regressed the number of offspring on the number of copies of H2 a person carries (i.e., an additive model), adjusted for year of birth and sex. We used weighted regression to adjust for the fact that people who have more children are over-represented in the genotyped samples (Supplementary Table 3 online). Because the individuals are related and their genotypes are not independent, we determined standard errors and P values empirically by carrying out 10,000 simulations of the H2 lineage through the entire Icelandic genealogy. The estimated effect of H2 chromosomes for both sexes combined, assuming an additive model, is an increase of 0.0623 children per copy with a two-sided P value of 0.0056. Upon closer examination, we found that homozygous carriers of H2 have, on average, fewer children than heterozygous carriers, although the difference is not statistically significant. Hence, the additive model, which assumes that homozygous carriers have more children than heterozygous carriers, is not a good fit. We refitted the data assuming a dominant effect for the H2 and assuming that heterozygous and homozygous carriers have the same number of children on average (Table 1). With both sexes combined, a carrier of H2 is estimated to have 0.0796 more children than a noncarrier (P = 0.0025). For women, the estimated effect is 0.0907 (P = 0.0068), which translates to an increase of approx3.5%, as women in this era had an average of 2.584 children. For men, the estimated effect is 0.0679 (P = 0.0719) or approx2.9% of 2.369 (the average number of children for men in this era). The estimated effect for men is insignificant and smaller than that for women but probably real. Results from fitting a full model for H2 status are presented in Supplementary Table 4 online.

[...]

Whether retained by balancing selection or introduced by another hominin species, the H2 lineage in contemporary humans seems to have an African origin (see Fig. 3b). H2 chromosomes were probably rare in the groups that left Africa more than 60,000 years ago and gave rise to the populations of Europe and Asia29, on the basis of the observation that H2 chromosomes are presently rare in Africans and almost nonexistent in Asians. The higher frequency of H2 chromosomes in European populations, coupled with extreme homogeneity, is consistent with a rapid expansion from a few founder chromosomes, probably owing to positive selection......A number of studies have inferred the action of positive selection on haplotype structure18, 30, 31, 32, 33, and some have identified geographic differences in selection histories similar to that reported here for 17q21.31 (ref. 34).

I'm sorry Anton, you're simply wrong here. You have provided no evidence that chromosome mutations are only maintained by genetic drift. I just provided you with numerous papers to the contrary (which you need to read). Of course, you are free to have your opinion, but as you just demonstrated, opinions need not agree with reality -As seems to be the case here.

Having dealt with the chance issue, the horse issue is dealt with accordingly: http://www.truthinscience.org.uk/site/content/view/55/65/

Anton,

In the future it might help for you to use the specific quote function embedded in this site to highlight part(s) of the link you think support what you are talking about. This will; A. help people follow along with your line of thought more easily and B. keep you from just garbage posting links.

That all said, I took some time to go over the link you provided. First let me reiterate those points and questions I asked you to address about horses and their evolution:

1. So what, (since the flood) has caused the different number of chromosomes?

2. So we have differential evolution of chromosome number, which undoubted has undergone natural selection at some point. Which defeats the whole purpose of your argument, that 'chromosome mutations' only become fixed by chance.

So let's look at your links 'argument'

The Basic Type concept has been applied to horses, both living and extinct forms (Cavanaugh et al 2003; Garner 1998; Stein-Cadenbach 1993). These studies suggest that all horses, including the 150 or so fossil species, are probably related in a single Basic Type. The ancestor(s) of these horses probably possessed latent (i.e. unexpressed) genetic information that gave the horse type tremendous potential for variety. One way in which this latent genetic potential may be regulated is by differential gene expression. By this we mean that in living organisms there are mechanisms by which genes can be turned on (i.e., expressed) or turned off (i.e., not expressed). For example, horses may have a genetic ‘switch’ that determines whether they develop side toes. Other regulatory genes may control size, shape of the teeth, and so on.

And the summary of their argument:

The evidence of fossils, along with the study of horse embryos, indicates that the horse series is a genuine record of biological change over time. Evolutionary scientists point to this as evidence of Darwinian evolution. However, non-evolutionary scientists say that this simply records changes within the horse basic type and that there is little evidence to suggest that horses developed from a non-horse ancestor. Since the magnitude and type of change represented by the horse series can be accommodated by both evolutionary and non-evolutionary theories it cannot, therefore, distinguish between them. At best, in terms of the origins debate, the horse series is neutral data.

Sadly, their only sources on the matter above are to creationist literature, which we know is not a very credible body of work, if history speaks anything of truth.

So maybe you can elaborate on how this address those points above?

To my knowledge artificial insemination trials have yet to be conducted on these two organisms.

No, the attempts at breeding were done by professional Felid breeders over a period of years. The reproductive organs of the margay and oncilla are nearly identical (as with almost all cats).Whether the depositing of sperm in the female reproductive tract is done via the male organ or a turkey baster, makes little difference in this case.

The more simple, yet elegant point, is that there are examples of 2 animals which will not hybridized with each other, but will with common other animal. Which, from your definitions above, means that must be new kinds being created in this process.

Another example I believe is the Arctic fox, Swift fox and Kit fox. I believe (off the top of my head) that the swift fox and kit fox readily hybridize, as do the arctic fox and kit fox, but not the arctic and swift.

I have used the term "survival of the fittest" loosely to donate "advantage" that's all. Chromosomal mutations marginalise natural selection to a sub-speciation role

To the boldface, How so? Are you expressing your opinion here? Or do you have evidence to support your claim? At the chance of sounding like a broken record here; The neat thing about reality, is that it doesn't need to conform to our opinions. While anyone is free to have any opinion they wish, the existence of the opinion, has no bearing on its truth.

This is the third time I have you asked you to explain why this should happen, if you can't answer it (outside of your opinion) then concede the point and move on.

The title of the book "Origin of species by means of natural selection" should be replaced by "Origin of species by means of genetic drift". Darwin mistakenly believed that Darwinian speciation (sub-speciation) was principally driven by natural selection when in fact genetic drift is the principle player both in sub-speciation and genetic decoupling. Thus chromosomal mutation via genetic drift replaces natural selection as the predominant driver of evolution . I realise there was no such thing as genetic drift in Darwins day.

Not to be a stickler here Anton, but maybe you missed this part of the rules when you joined:

2d. Accuracy: Do not post material that is knowingly or intentionally false, inaccurate or misleading.

Please provide evidence for your above statement(s).

This argument is equally attributable to a common designer!

Evidence Anton, evidence.

The laws of science are based on randomness(chaos).

Evidence. The idea that nature works in certain, recurrent ways, means it is not random. Please look up how random is used in science Anton.

Abiogenises, the spontaneous generation of life from chemicals would have to occur randomly (chaotically) as there would be no reproduction to invoke "survival of the fittest".

Abiogenesis=/=biological evolution. Similarly, reproduction=/=replication. Natural selection needs only one of these (reproduction or replication) to act.

There are numerous other topics on abiogenesis, if you wish to discuss that, then lets move this part of the discussion to one of them. This website has a very convenient 'search' function. Please use that to find some of those topics.

True Evolution (chromosome mutation) is a random (chaotic ) process. These three fundamentals have chaos (randomness) at their roots. Chaotic fundamentals suggest some sort of magic or miracle; a miracle requires a miracle worker and that miracle worker could be a God.......

Unfortunately, you don't get to define what evolution is. As the biological fact of evolution is simply that allele frequencies change from generation to generation for a population. That is the natural fact of evolution (or 'true' evolution, you might be inclined to say). Furthermore, you have provided no evidence to substantiate your claim so outside of your opinion, has no merit for argument's sake.

And remember expressing something as your opinion is certainly okay, but if you wish to claim something to be fact or a 'rule of science' or make definitive statements about the nature of a scientific study, it would be wise to either make sure its clear you are expressing your opinion or provide the evidence to substantiate your claims.

[antonT]

Your belief is irrelevant Anton, and has no bearing on reality.

The trouble with you Copasetic is that because you are a biologist (undoubtedly a very good one at that) and also a confirmed evolutionist you do not appear to be willing to think outside your vocational box. I however have no such constraints as you will find out later and can therefore afford to give a totally objective appraisal of the subject - totally free of prejudice and bias. Your whole language with respect is the language of scientific dogma whilst your literary demeanour is that of someone entrenched in an uncompromising belief that what you espouse is absolute fact.

Detailed science has spoilt the layman to such an extent that, spoilt brat that he has become, before he accepts evolution as fact, he requires detailed evidence - such evidence as say of that in embryology where an unbroken continuum of the development of an embryo from the cradle of life to the grave can be evidenced. Now that is the standard of evidence required. Now that is fact - anything less flirts with fiction.

Life itself is irreducibly complex, If one takes away its one and only component one gets death. When the first rung of Life's ladder is missing, all the other rungs are immediately suspect. What happens then when, as in the case of evolution, not only is there no initial step but there are no foundations either?

I will deal with your various points in due course.

[Cimber]

The trouble with you Copasetic is that because you are a biologist (undoubtedly a very good one at that) and also a confirmed evolutionist you do not appear to be willing to think outside your vocational box. I however have no such constraints as you will find out later and can therefore afford to give a totally objective appraisal of the subject - totally free of prejudice and bias. Your whole language with respect is the language of scientific dogma whilst your literary demeanour is that of someone entrenched in an uncompromising belief that what you espouse is absolute fact.

Detailed science has spoilt the layman to such an extent that, spoilt brat that he has become, before he accepts evolution as fact, he requires detailed evidence - such evidence as say of that in embryology where an unbroken continuum of the development of an embryo from the cradle of life to the grave can be evidenced. Now that is the standard of evidence required. Now that is fact - anything less flirts with fiction.

Life itself is irreducibly complex, If one takes away its one and only component one gets death. When the first rung of Life's ladder is missing, all the other rungs are immediately suspect. What happens then when, as in the case of evolution, not only is there no initial step but there are no foundations either?

I will deal with your various points in due course.

Science is about the pursuit of knowledge without bias. Copasetic is not exhibiting any bias, merely stating that evolution is both theory and fact. There's no ifs ands or buts about it. Thinking outside the box is great, but not when you start throwing scientific facts out the window.

Irreducible complexity is outright false. We've been through this with the flagellum, which the creationist argument for its irreducible complexity was utterly thrown out the window in the Dover Trial.

In addition, Copasetic has done a terrific job explaining this to you.

Edited February 22, 2009 by Cimber

[churchanddestroy]

The trouble with you Copasetic is that because you are a biologist (undoubtedly a very good one at that) and also a confirmed evolutionist you do not appear to be willing to think outside your vocational box. I however have no such constraints as you will find out later and can therefore afford to give a totally objective appraisal of the subject - totally free of prejudice and bias. Your whole language with respect is the language of scientific dogma whilst your literary demeanour is that of someone entrenched in an uncompromising belief that what you espouse is absolute fact.

Detailed science has spoilt the layman to such an extent that, spoilt brat that he has become, before he accepts evolution as fact, he requires detailed evidence - such evidence as say of that in embryology where an unbroken continuum of the development of an embryo from the cradle of life to the grave can be evidenced. Now that is the standard of evidence required. Now that is fact - anything less flirts with fiction.

Life itself is irreducibly complex, If one takes away its one and only component one gets death. When the first rung of Life's ladder is missing, all the other rungs are immediately suspect. What happens then when, as in the case of evolution, not only is there no initial step but there are no foundations either?

I will deal with your various points in due course.

Erm, not to but in, seeing as how I don't have my degree in biology yet, but as Cimber pointed out irreducible complexity was thoroughly debunked at during the Dover, PA, "Panda" trial.

Here is a link to the video: http://www.pbs.org/wgbh/nova/id/program.html

Cimber sent this to me and others a while back. If you would kindly review part 8, Ken Miller makes a compelling case as to why irreducible complexity is bunk.

As a side note, that you would claim to have a wholly objective standpoint while simultaneously using the language used by proponents of intelligent design... sorta discredits that objectivity. ID is not a scientific... anything. Its just not science. However, if you are more interested in the concept of "design" in the world, I suggest that you take a look at the teleological argument of philosophy. You won't get anywhere in science with ID, but the teleological argument might set you on the path you want to go.

Cheers.