Sex chromosomes and speciation in Drosophila.
Two empirical rules suggest that sex chromosomes play a special role in speciation. The first is Haldane's rule - the preferential sterility and inviability of species hybrids of the heterogametic (XY) sex. The second is the disproportionately large effect of the X chromosome in genetic analyses of hybrid sterility. Whereas the causes of Haldane's rule are well established, the causes of the 'large X-effect' have remained controversial. New genetic analyses in Drosophila confirm that the X is a hotspot for hybrid male sterility factors, providing a proximate explanation for the large X-effect. Several other new findings -- on faster X evolution, X chromosome meiotic drive and the regulation of the X chromosome in the male-germline -- provide plausible evolutionary explanations for the large X-effect.
Department of Biology, University of Rochester, Rochester, NY 14627, USA. dvnp@mail.rochester.edu <dvnp@mail.rochester.edu>
Daven C
DC
Presgraves
D000818:Animals; D004330:Drosophila / Q000235:genetics*; D019143:Evolution, Molecular; D049810:Genetic Speciation; D007246:Infertility; D008297:Male; D012730:Sex Chromosomes / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics