Other Comments
Cope's gray treefrog (H. chrysoscelis) and the Eastern gray treefrog (H. versicolor) are a unique example of speciation in action. The two species have very similar genes, and appear identical; however, the eastern gray treefrog possesses a second chromosome set, twice the number of chromosomes as Cope's gray treefrog. Cope's (H. chrysoscelis) is called a diploid, and the eastern (H. versicolor) is called a tetraploid. The only reliable ways to distinguish between the species are by the calls of the males or by microscopic examination of their chromosomes. (Collins and Conant, 1998)
H. versicolor is thought to have evolved from H. chrysoscelis when an extra chromosomal set was passed to several surviving egg masses sometime early in the Pleistocene epoch, commonly known as the "Ice Age." At this time, populations of H. chrysoscelis were isolated by intervening areas of extreme low tempoeratures. By the time the climate warmed and the glaciers retreated, the two populations had evolved in different directions, and though they now occur together, they no longer interbreed and are different species. (Gerhardt, Ptacek, and Sage, 1994; Harding, 1997)
rosborne979 wrote:rosborne979 wrote:Populations almost always change. They flow away from their original form over time erasing their ancestral trail as they go. Extinction events wipe out particular branch populations and leave dramatic gaps in the fossil record. But more often an ancestor form is simply superceded by its more specialized decendents and they simply dwindle away slowly and quietly. It's relatively rare to find an existing animal that has an existing ancestor still in its original form.
After making that last post I started trying to think of an existing animal with an existing ancestor is its original form. I couldn't think of a single one, so I started This Thread. It now seems that it's not just 'relatively rare' to find animals like this, but they may not exist at all (at least, so far, nobody else can name one either).
If evolution were really happening today, there should be tens of thousands of examples.
real life wrote:rosborne979 wrote:rosborne979 wrote:Populations almost always change. They flow away from their original form over time erasing their ancestral trail as they go. Extinction events wipe out particular branch populations and leave dramatic gaps in the fossil record. But more often an ancestor form is simply superceded by its more specialized decendents and they simply dwindle away slowly and quietly. It's relatively rare to find an existing animal that has an existing ancestor still in its original form.
After making that last post I started trying to think of an existing animal with an existing ancestor is its original form. I couldn't think of a single one, so I started This Thread. It now seems that it's not just 'relatively rare' to find animals like this, but they may not exist at all (at least, so far, nobody else can name one either).
If evolution were really happening today, there should be tens of thousands of examples.
I knew you would say that
Geetic diversity compounds and subspecies interbreed until the adaptation prevents ceratin individuals from breeding within the subspecies and so a new species is formed.
I think he's being purposefully obtuse AND dense.
Let's try to lay this out even clearer for you.
Step 1) You have 1 species of Ape
Step 2) At some point (long period of time) this species ends up in two groups sexually isolated from each other, by distance, water, mountains, etc.
Step 3) Each group of apes can mate with the same group over and over again, producing many generations of offspring with subtle mutations building up over time.
Step 4) After 65 million years, humans try to have the ape from group A mate with the ape from group B and the offspring is infertile or the mating cannot occur.
Step 5) Now you have 2 different species.
What you're trying to claim is that speciation occurs when an ape from Group A has an offspring that cannot mate with any other Group A ape. This does not form new species. That ape would die off, unable to pass any genetic information.
maporsche wrote:I think he's being purposefully obtuse AND dense.
Let's try to lay this out even clearer for you.
Step 1) You have 1 species of Ape
Step 2) At some point (long period of time) this species ends up in two groups sexually isolated from each other, by distance, water, mountains, etc.
Step 3) Each group of apes can mate with the same group over and over again, producing many generations of offspring with subtle mutations building up over time.
Step 4) After 65 million years, humans try to have the ape from group A mate with the ape from group B and the offspring is infertile or the mating cannot occur.
Step 5) Now you have 2 different species.
What you're trying to claim is that speciation occurs when an ape from Group A has an offspring that cannot mate with any other Group A ape. This does not form new species. That ape would die off, unable to pass any genetic information.
hi maporsche,
No, I'm really not trying to be trying.
But do you really believe that unless a complete geographic separation lasting thousands or millions of years occurs, that a new species won't develop?
If so, you're proposing quite a bit more dramatic event(s) than 'the bear went over the mountain , to see what he could see......'
How many hundreds of millions of these cataclysmic geographical events do you propose have happened over history (and must still be happening)?
And what about 'closely related species' that are obviously NOT separated geographically?
