A question about evolutionary theory

[Mojo]

Who doesn't agree that a cat is a cat?

But that, of course, isn't what AiG are saying, as you would have realised if you'd bothered to look at the diagram before commenting on it. What they are suggesting is that a cat is a cheetah is a tiger. Do you agree with that?

 

[hammegk]

Perhaps that isn't what AiG said, but it's what I said.

It's also the question I asked Dr.A. on the dna dis-similarity across housecats-cheetahs-etc that he is apparently unwilling (or unable) to answer.

I suggest only that dna analysis would provide actual data to examine. For the moment, do you suspect that chihuahuas & great danes have 'different' dna? I don't.

 

[Paul C. Anagnostopoulos]

Hammegk said:
Paul: Hammegk's Theory of ID -- the most minimal intelligence involved is the Strong Anthropic Principle. Tell me again how random evolution selected -- and continues to select-- for quarks, leptons, etc.

I have no idea what you're talking about.

I suggest only that dna analysis would provide actual data to examine. For the moment, do you suspect that chihuahuas & great danes have 'different' dna? I don't.

You mean they're different due to something other than DNA?

~~ Paul

 

[hammegk]

I have no idea what you're talking about.

So it seems.

You mean they're different due to something other than DNA?

~~ Paul

Nope, the question remains -- how different. More than the chimp/homosap spread? And sfaik, the answer is a resounding "no" for dogs; the question remains for cats.

 

[drkitten]

Nope, the question remains -- how different. More than the chimp/homosap spread? And sfaik, the answer is a resounding "no" for dogs; the question remains for cats.

Boy, you really don't have a clue what you're talking about, do you?

When you say "dogs," do you mean Canis lupis familiaris? I suspect that you do, given that you are presenting "Great Danes" and "chihuahuas" as extrema. It's unsurprising that two animals that are not only members of the same species, but members of the same subspecies, should have very similar DNA.

As it happens,chihuahuas and Great Danes do not have identical DNA. For a more detailed report, read this article from Science. But that's fairly minor.

If you want to take a broader view of "dogs," then you're looking at the entire Canidae family which does have much greater genetic diversity than the population of Homo sapiens or the difference between Homo sapiens and Pan spp..

But you were specifically asking about "cats," which I interpret from your comments to mean Felidae. If you want some evidence about the genetic diversity of this group, check out this paper from J. Molecular Evolution, this paper from Molecular Biology and Evolution , and this paper from Genetics. If you want a direct cat-to-human comparison, your best bet is probably this site here at the National Cancer Institute, but they only focus on the domestic house cat, not on Felidae as a group, for obvious reasons.

 

[hammegk]

Boy, you really don't have a clue what you're talking about, do you?

Naw, I'm just a pore ole country boy. And unfortunately

Fig. 2.—Phylogenetic reconstruction of SINE sequences from carnivore species. Shown is a tree constructed by minimum evolution estimated by the neighbor-joining (NJ) algorithm using the Tajima-Nei (Tajima and Nei 1984 ) model of substitution as implemented by PAUP, version 4.0b2 (used by permission from D. Swofford). A nearly identical topology (length = 427 steps; consistency index = 0.7869) is obtained from a 50% majority-rule consensus of 44 equivalent trees derived from maximum-parsimony (MP) analyses with PAUP. A nearly identical maximum-likelihood (ML) tree (-ln likelihood = 1,184.28; 524 trees examined) is obtained using PHYLIP, version 3.5 (Felsenstein 1993 ). Both MP and ML trees differ from the NJ tree shown here by slight rearrangements of internal branches within the Ursidae lineage. Branch lengths are percentages of sequence divergence (genetic distance x 100) computed by minimum evolution estimated by NJ with the Tajima-Nei model of substitution. Nodes supported by the ML analyses are indicated by asterisks. Bootstrap proportions (%) greater than 50% are based on 100 iterations with NJ above and MP values below

and

The 37 species of modern cats have evolved from approximately eight phylogenetic lineages within the past 10 to 15 million years. The Felidae family has been described with multiple measures of morphologic and molecular evolutionary methods that serve as a framework for tracking gene divergence during brief evolutionary periods. In this report, we compare the mode and tempo of evolution of noncoding sequences of a large intron within Zfy (783 bp) and Zfx (854 bp), homologous genes located on the felid Y and X chromosomes, respectively. Zfy sequence variation evolves at about twice the rate of Zfx, and both gene intron sequences track feline hierarchical topologies accurately. As homoplasies are infrequent in patterns of nucleotide substitution, the Y chromosome sequence displays a remarkable degree of phylogenetic consistency among cat species and provides a highly informative glimpse of divergence of sex chromosome sequences in Felidae.

didn't help overmuch.

Of the 8 cat-families recognized, apparently they all have, iirc, 19 chromosomes, so are they not closer than is chimp to human?

When you say "dogs," do you mean Canis lupis familiaris? I suspect that you do, given that you are presenting "Great Danes" and "chihuahuas" as extrema. It's unsurprising that two animals that are not only members of the same species, but members of the same subspecies, should have very similar DNA.

As it happens,chihuahuas and Great Danes do not have identical DNA. For a more detailed report, read this article from Science. But that's fairly minor.

Er, yup. Now what?

If you want to take a broader view of "dogs," then you're looking at the entire Canidae family which does have much greater genetic diversity than the population of Homo sapiens or the difference between Homo sapiens and Pan spp..

"Genetic diversity" based on what? For a start, do Canidae share the same number of chromosomes?

But you were specifically asking about "cats," which I interpret from your comments to mean Felidae.

Yup. Are you stating that in your understanding of the data Felidae show greater genetic diversity than does chimp to human?


Finally, thanks for finding and sharing some actual data.

 

[Paul C. Anagnostopoulos]

Getting excited about the number of chromosomes is like getting excited about the number of boxes you have your CD collection stored in. It may be exciting when it comes to interbreeding, but it's not too exciting when it comes to playing music.

I believe all Canidae do not have the same number of chromosomes.

~~ Paul

 

[Paul C. Anagnostopoulos]

Looks like all Felidae have 38 chromosomes except the leopard, which has 36. Gotta love those fusion events!

~~ Paul

 

[drkitten]

Of the 8 cat-families recognized, apparently they all have, iirc, 19 chromosomes, so are they not closer than is chimp to human?

Er, no.

Chromosome count is not actually a good measure of relatedness; it's fairly common (genetically speaking) both for chromosomes to break apart (yielding two where there were one) and to join. It's similarly fairly common for genes to transpose themselves, either moving from one physical location on a chromosome to another location, or even to move from one chromosome to an entirely different chromosome. If you want an analogy, you might think of how two different editions of the same book may have different paginations -- or how one might take three books and bind them into a single volume and sell as a complete "trilogy." I have such a single-volume copy of "The Lord of the RIngs."

So if you're measuring typological and genetic relatedness using the chromosome count, you're making a fairly elementary procedural error.

For this reason, geneticists focus on comparisons of genes, not of whole chromosome. For example, one can identify the analogues of both alpha and beta hemoglobin (in humans) in the cat, wherever they might be located on the chromosomes. (Continuing the analogy, this would be like me finding 'the scene where Pippin meets Denethor.' In some editions, that's near the front of the third volume, and in the single-volume edition, it's about two-thirds of the way through the book.) We can also directly compare to see how similar (in terms of base pairs) the cat analogues are to human hemoglobin. We might find they are base-for-base identical, we might find they are somewhat changed, and in some (rare) cases, we might find there is no analogous gene whatsoever, on any chromosome. (I believe that the human green visual receptor has no feline analogue; it's a recent mutation with the primate lineage, which we don't share [the lineage or the gene] with Felidae, but do share with Pan spp.. Just for example. I know of no similar examples of genes we share with Felidae but do not share with Pan, but I'm willing to be corrected if anyone has data.)

Yup. Are you stating that in your understanding of the data Felidae show greater genetic diversity than does chimp to human?

I am. I would be interested in seeing what data you have that refutes this.

 

[drkitten]

Looks like all Felidae have 38 chromosomes except the leopard, which has 36. Gotta love those fusion events!

Really? Cute. I didn't know that....

But just to hammer a point home, this illustrates the mistake in using simple chromosome counts as a measure of relatedness. The leopard is technically known as Panthera pardus, and shares its genus with three other Panthera members : the lion P. leo, the tiger P. tigris and the jaguar P. uncia. There are a number of other so-called "big cats" that are not Panthera, such as the cougar Puma concolor, the cheetah Acinonyx jubatus and the Tibetian snow leopard Uncia uncia.

From the name (and from molecular studies in general), one would expect the genus Panthera to be closely related within the cats, as indeed it is. But from a simple chromosome count, we would conclude (erroneously) that the lion is more closely related to the cougar than to the leopard.

 

[hammegk]

Chromosome count is not actually a good measure of relatedness; ...

My stupid error. I should have done a bit of homework ....

Do you like this layman's overview?
http://eichlerlab.gs.washington.edu/news/pix/Nature52302.pdf

I am. I would be interested in seeing what data you have that refutes this.

I have none. At this point my question will become "what do we mean by "genetic similarity" across "species", and what is the role if any of junk dna?".

Over the past few years, is it not correct that a significant portion of what was considered junk has been found to be required for viability?

 

[drkitten]

At this point my question will become "what do we mean by "genetic similarity" across "species", and what is the role if any of junk dna?"

Answered in the papers cited previously.

 

[Paul C. Anagnostopoulos]

Hammegk said:
I have none. At this point my question will become "what do we mean by "genetic similarity" across "species", and what is the role if any of junk dna?".

It's becoming clear that "junk DNA" includes DNA that plays a regulatory role rather than participating in translation. This may turn out to be one avenue toward explaining the apparent differences between species that are genetically close. The equation for computing the "difference" between two species is going to become more complex.

~~ Paul

 

[Mojo]

Perhaps that isn't what AiG said, but it's what I said.

On the other hand, you said it as a comment, apparently, on the AiG diagram:

Originally posted by Dr Adequate
See Mojo's link to AiG. Observe the diagram showing that cats are one kind.

Who doesn't agree that a cat is a cat?

You now seem to be saying that your comment was entirely irrelevant to what was being discussed. What, then, was the point of it?

 

[hammegk]

Answered in the papers cited previously.

Not in a way that I could make sense of.

For example

http://www.agu.org/revgeophys/buckli01/node3.html

does provide a definition. Moving from that to a computation of the variation among Felidae and comparing it to the variation homo sap to Pan spp is not anything I understand how to accomplish. Are you aware of a source for a compution that has been done?

You now seem to be saying that your comment was entirely irrelevant to what was being discussed.

I did?

What, then, was the point of it?

To provide you with a nit to pick? Your welcome.

 

[Mojo]

I have always wondered, are bats and mice the same kind? Look at a bat and tell me that isn't just a friggin mouse with wings ("Die Fledermaus" is not hyperbole)

Actually, they're more like shrews, in that they're small insectivorous mammals.

from here
While bats are highly specialized for flight, they share anatomical characters with the Insectivora, the mammalian taxon that includes shrews and moles.

It appears, though, that they're not closely related to the insectivora. They actually seem to be more closely related to primates!

I did discover that shrews also use echo-location. You learn something new every day!

 

[RandFan]

I did discover that shrews also use echo-location.

I don't know about that. Can they (shrews) be trained? It seems to me that Bill equivicates on this point.

 

[Dr Adequate]

I don't know about that. Can they (shrews) be trained?

Ay, mistress; and Petruchio is the master,
That teacheth tricks eleven and twenty long,
To tame a shrew and charm her chattering tongue.

 

[Mercutio]

I love this place.

 

[Paul C. Anagnostopoulos]

Me, too.

Hammegk said:
... does provide a definition. Moving from that to a computation of the variation among Felidae and comparing it to the variation homo sap to Pan spp is not anything I understand how to accomplish. Are you aware of a source for a compution that has been done?

I've completely lost track of the point of this conversation.

~~ Paul