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The origin and function of the mammalian Y chromosome and Y‐borne genes – an evolving understanding
Author(s) -
Graves Jennifer A. Marshall
Publication year - 1995
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.950170407
Subject(s) - testis determining factor , pseudoautosomal region , y chromosome , biology , genetics , gene , heterochromatin , x chromosome , homologous chromosome , evolution of mammals , dosage compensation , vertebrate , function (biology) , evolutionary biology , chromosome
Mammals have an XX:XY system of chromosomal sex determination in which a small heterochromatic Y controls male development. The Y contains the testis determining factor SRY , as well as several genes important in spermatogenesis. Comparative studies show that the Y was once homologous with the X, but has been progressively degraded, and now consists largely of repeated sequences as well as degraded copies of X linked genes. The small original X and Y have been enlarged by cycles of autosomal addition to one partner, recombination onto the other and continuing attrition of the compound Y. This addition–attrition hypothesis predicts that the pseudoautosomal region of the human X is merely the last relic of the latest addition. Genes (including SRY ) on the conserved or added region of the Y evolved functions in male sex determination and differentiation distinct from the general functions of their X‐linked partners. Although the gonadogenesis pathway is highly conserved in vertebrates, its control has probably changed radically and rapidly in vertebrate – even mammalian – evolution.