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r
e s e a r c h.. f o c u s :
Reproductive
isolation
To
understand how new species come into existence, we need to understand
how barriers to interbreeding arise between new species and their
ancestors. For any particular case, reproductive isolation (RI)
is not likely to be due to any one particular factor, and premating,
postmating/prezygotic, and postzygotic mechanisms may all contribute
to the reproductive breakdown. We are investigating whether the
rapid divergence in sperm morphology observed among Drosophila
and other taxa represents a widespread engine of speciation. That
is, with restricted gene flow among populations, any divergence
in sperm length, coupled with coevolutionary changes in the female
reproductive tract, may compromise sperm-female compatibility in
among-population crosses. Moreover, postzygotic studies have presumed
that all hybrid inviability is due to genetic incompatibility between
sperm and egg donors. Extragenic sperm-egg interactions may represent
a potent, yet unexplored, class of postzygotic RI mechanisms. If
female sperm-storage organ morphology, egg cytochemistry, and important
life history attributes all tend to rapidly evolve in concert with
sperm morphology, this would have the potential to generate rapid
RI.
Selected
Related Publications:
Pitnick,
S., Miller, G. T., Schneider, K. and T. A. Markow. 2003. Ejaculate-female
coevolution in Drosophila mojavensis. Proceedings of the
Royal Society of London B, 270: 1507-1512. [PDF].
Miller,
G. T., Starmer, W. T. and S. Pitnick. 2003. Quantitative
genetic analysis of among population variation in sperm and female
sperm-storage organ length in Drosophila mojavensis. Genetical
Research, 81: 213-220. [PDF].
For
more details and selected publications on the different aspects
of my research program, follow these links:
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