Mammalian sex chromosomes: design or accident?
Mammalian sex chromosomes evolved (and are still evolving) from a homomorphic pair by the progressive loss of active genes from the Y chromosome. Among the changes that have accompanied this differentiation, it is difficult to determine causes, effects and correlates. Comparative studies suggest that the choice of a gene, and thus a chromosome pair, to control the sex-determining pathway may be quite arbitrary, and that sex chromosomes and sex-determining genes are more likely to be the products of random changes than the products of selection for function.
Graves
J A
JA
Department of Genetics and Human Variation, La Trobe University, Melbourne, Australia.
Schmidt
M M
MM
D000818:Animals; D005075:Biological Evolution; D004303:Dosage Compensation, Genetic; D005260:Female; D008297:Male; D008322:Mammals; D012730:Sex Chromosomes; D012732:Sex Determination Analysis