Inefficient purifying selection: the mammalian Y chromosome in the rodent genus Mus.
Two related genes with potentially similar functions, one on the Y chromosome and one on the X chromosome, were examined to determine if they evolved differently because of their chromosomal positions. Six hundred fifty-seven base pairs of coding sequence of Jarid1d (Smcy) on the Y chromosome and Jarid1c (Smcx) on the X chromosome were sequenced in 13 rodent taxa. An analysis of replacement and silent substitutions, using a counting method designed for samples with small evolutionary distances, showed a significant difference between the two genes. The different patterns of replacement and silent substitutions within Jarid1d and Jarid1c may be a result of evolutionary mechanisms that are particularly strong on the Y chromosome because of its unique properties. These findings are similar to results of previous studies of Y chromosomal genes in these and other mammalian taxa, suggesting that genes on the mammalian Y evolve in a chromosome-specific manner.
Sandstedt
Sara A
SA
Department of Ecology and Evolutionary Biology, and Museum of Zoology, University of Michigan, Ann Arbor, Michigan 48109, USA. sandsted@umich.edu
Tucker
Priscilla K
PK
D000818:Animals; D005075:Biological Evolution; D005260:Female; D020868:Gene Silencing; D008297:Male; D051379:Mice; D010802:Phylogeny; D051381:Rats; D014960:X Chromosome; D014998:Y Chromosome