Graduate school is finally starting up, and I really think that I am going to like it at UTA. This first semester I am taking advanced genetics, population genetics, a natural selection seminar, and independent study with my advisor. I have a lot of catching up to do in my understanding of genetics, but the advanced genetics course is really a fast paced review of general genetics so that will certainly help out.
For my independent study I am reviewing a lot of old literature on Coleoptera cytogenetics which is really interesting. It is amazing how diverse the genomes of Coleoptera have become in 250 million years. My genetics professor mentioned that genomes are much more modular and adaptable than we once thought. This is really obvious in my cytogenetics review when you see how often closely related species posses strikingly divergent karyotypes.
My advisor is also passing a lot of interesting speciation genetics books and articles my way. Yesterday I read chapter 19 out of Endless Forms: Species and Speciation. This chapter by William Rice is a look at the different types of evolutionary conflict and the relative importance of interspecific vs intraspecific sources of conflict. Rice thinks that the importance of intergenomic conflict has been underestimated as a source for the genetic divergence that leads to reproductive isolation.
Intergenomic conflict is basically conflict between two members of the same species involving coevolution were one group, say males, evolves an advantage that the females evolve a response to and this continues over and over again.
To support the theory that intergenomic conflict is an important source of evolutionary conflict Rice designed a simple experiment that shows, at a minimum, that there is ample genetic diversity to allow evolution in this area. His experiment used a Drosophila melanogaster line to mimic a hybridogenetic breeding system. In the case of his experiment it was the males that were semiclonal. He bred this population for 30 generations always drawing the females for each generation from a stock population. This allowed the males to evolve without allowing the females to evolve in response. At the end of this process he bred original stock males and the line bred males with the original stock females. Looking at a number of categories (fertilization, number of offspring, remating, etc.) he found that the new males were roughly 20% more successful than the stock males.
I have known for years that many beetles can only be distinguished by examining the genitalia, but I had never really stopped to consider the evolutionary meaning behind this. After reading this though it is easy to imagine that a slight change in the shape of a male genitalia might allow for a better fertilization rate or reduce the likelihood of subsequent males success in remating.
For details on the "clone generator" females that allowed him to mimic a hybridogenetic breeding system read his chapter:
1998 Rice, W. R. Intergenomic conflict, interlocus antagonistic coevolution, and the evolution of reproductive isolation. pp. 261-270 In: Howard, D. J., & Berlocher, S. H. (Eds.) Endless Forms: Species and Speciation. Oxford University Press.
