Essentially, is this the position of a large # of people?

[lucaspa]

Today at 11:01 AM webboffin said this in Post #79

SO far Notto your evolution has shown that you can improvise on a breed of species but where does it break away from being from one species and becoming another seperate species in it's own right?

For sexually reproducing populations, when they become reproductively isolated.  That is, when the two populations no longer interbreed.  Notice that this can include cases where they simply don't choose to breed or can't breed due to genital incompatibility or aren't around at the same time to breed (one is nocturnal and the other isn't).

In the lab, one example of where this happened is:
1.  G Kilias, SN Alahiotis, and M Pelecanos A multifactorial genetic investigation of speciation theory using drosophila melanogaster  Evolution 34:730-737, 1980. 

In the wild, an example is:
12. N Barton Ecology: the rapid origin of reproductive isolation Science 290:462-463, Oct. 20, 2000. www.sciencemag.org/cgi/content/full/290/5491/462 Natural selection of reproductive isolation observed in two cases. Full papers are:  AP Hendry, JK Wenburg, P Bentzen, EC Volk, TP Quinn, Rapid evolution of reproductive isolation in the wild: evidence from introduced salmon. Science 290: 516-519, Oct. 20, 2000. and M Higgie, S Chenoweth, MWBlows, Natural selection and the reinforcement of mate recognition. Science290: 519-521, Oct. 20, 2000 

 

[lucaspa]

Today at 10:20 AM webboffin said this in Post #75

This is not an anti evolution post more of wanting answers.
Science has claimed there has been many mass extinctions of life during the Eath's bio history mainly from natural and cosmic disasters.
How does life get more complex when it has been reduced and larger more complex lifeforms having not been able to survive the altered more hostile enviroment were wiped out in mass extinctions on Earth and only the smaller simpler lifeforms being able to survive? And yet life had managed to kickstart it's own evolution process again so that a mammal like shrew creature that in less than 65 million years became into an ape then in a blink of an evolutionary eye became human and here we are today all in a few million years after our latest global catastrophe.

Web, do you have a precise defintion of "complexity"?  I don't think so and no one else does either.  Is a cow more "complex" than a shrew?  Is a bird more "complex" than a dinosaur?

When mass extinctions happen species go extinct, but that doesn't equate to going back to "simpler" organisms.  For instance, when the KT extinction happened 65 million years ago, life didn't go back to one-celled organisms.  Instead, already "complex" mammals occupied an ecological niche that allowed them to survive the climatic changes while the equally "complex" dinos were vulnerable. In the oceans, many species of one-celled plankton went extinct but not all.

The average speed of evolution in the fossil record is about 0.01 darwins and really fast evolution is about 0.3 darwins.  Yet in contemporary experiments we see evolution rates of 10 to 3,000 darwins, or over 10,000 times faster than in the fossil record.  Plenty of time for natural selection to give the change.

One reason for the "rapidity" is that developmental genes can give big phenotypic changes.  The whole field of evo-devo shows that. Go to the thread "evolution of feathers -- evolution of novelty" to see how small changes in developmental genes can go from scales to feathers.  Make small changes in the early genes that control development -- the Hox and other homeodomain genes -- and you get big changes in the form of the animal. For instance, simply leave the gene for BMP-2 active for 3 hours longer in early development and you can convert the round wrist bones to very long bones as are found in bats.