dubois@uwmacc.UUCP (A Ray Miller) (05/22/85)
Thank you Michael Lonetto for an absolutely gorgeous article. Even though you call me intractable, I will compliment you. Your posting on Drosophila speciation and its relation to natural selection was just marvelous. Of course, I can't let it go without comment! Especially since you asked for some: > I hope someone somewhere takes the trouble to read it and reply, I'm > interested in how it will sit with people on the net. --- > I know, I got a little carried away there with the technicalese, but you > know what I mean. More, more, please! --- > The result of such behavior is that a mating barrier developes between > populations of the same species. This barrier makes mating with the > other population disadvantageous and thus provides a selective advantage > to those flys that can recognize their own group. This in turn provides > an advantage to those flys from one of these groups that look or act or > smell(replace this line with your favorite sense) different than the > other group. Thus speciation can occur by branching off from a larger > population WITH NO SELECTIVE ADVANTAGE. In the case of Drosophila, > which produce many generations per year and are very prone to mutation > and variation this reduction in effective population size can easily > lead to rapid divergence of the two populations into two very similar > but distinct species. We would thus observe two sexually incompatible > but nearly identical species. In the case of Drosophila melanogaster > and its closesly related "sibling species" there are examples along a > continuum from freely interbreeding populations to distinct species. > Some of these species diverged as recently as a few thousand years ago, > some several million years ago. Thus we can formulate a TESTABLE model > which predicts that speciation can occur independant of selection and > lead to smaller effective populations which selection can operate much > more effectively upon than it can on the species as a whole. This model > also has the advantage of explaining the split between small gradual > changes and large abrupt changes (microevolution and macroevolution > >which is so often picked on by creationists< ) based on the population > size in which advantageous mutations occur. A bit speculative, but otherwise a marvelous paragraph. However, I wonder if this is not an odd use of the term "macroevolution". I thought it was supposed to refer to evolution of new structures and basic types (Bauplane, as Gould likes to say). You've applied it to simple speciation? I guess I'd like some amplification on this. > When I refer to the ideas above as a model I mean > that they are ideas in the process of verification. I don't expect that > all of them will be verified, but as more is learned some of the above > will be dropped, some will be refined and some will turn out to be right > as they are presented. The existance of these genetic elements in > bacteria has been known for less than 20 years, while their existance > in higher organisms has only been known for about ten. There is a great > deal of corroborating evidence for the model presented above for > speciation, but most of it is in the form of primary sources: research > reports written for other researchers in the same field, and is thus > somewhat dense. I'm looking around now for a more digested form of the > evidence and if I find it I will post it to the net. If not, I will > post my primary sources with explanations. Anxiously waiting! > On another note you may have noticed, I have presented a model for the > origin of new species. It has virtually nothing to do with evolution > other than providing it with isolated populations to operate upon. BRAVO!! Finally, someone who recognizes this possibility. > You may have noticed that I don't have the same faith in these models > and theories as many creationists seem to have in theirs. That has a > lot to do with the fact that science is not dependant on faith, but > rather on doubt, since faith may make you content, but doubt may make > you look for better explanations. Commendable. For all that we hear in this newsgroup about the virtues of doubt and skepticism, many of the evolutionists seem to number among the faithful. > SCIENCE LIVES! You have given me hope that this may be true. -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | |