Degeneration of a nonrecombining chromosome.
Comparative studies suggest that sex chromosomes begin as ordinary autosomes that happen to carry a major sex determining locus. Over evolutionary time the Y chromosome is selected to stop recombining with the X chromosome, perhaps in response to accumulation of alleles beneficial to the heterogametic but harmful to the homogametic sex. Population genetic theory predicts that a nonrecombining Y chromosome should degenerate. Here this prediction is tested by application of specific selection pressures to Drosophila melanogaster populations. Results demonstrate the decay of a nonrecombining, nascent Y chromosome and the capacity for recombination to ameliorate such decay.
Rice
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Department of Biology, University of California, Santa Cruz 95064.
D000818:Animals; D003433:Crosses, Genetic; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D005260:Female; D006239:Haplotypes; D008297:Male; D009154:Mutation; D011995:Recombination, Genetic; D014998:Y Chromosome