TY - JOUR
T1 - Sex determination in mammals - Before and after the evolution of SRY
AU - Wallis, M. C.
AU - Waters, P. D.
AU - Graves, J. A.M.
PY - 2008/10
Y1 - 2008/10
N2 - Therian mammals (marsupials and placentals) have an XX female: XY male sex chromosome system, which is homologous to autosomes in other vertebrates. The testis-determining gene, SRY, is conserved on the Y throughout therians, but is absent in other vertebrates, suggesting that the mammal system evolved about 310 million years ago (MYA). However, recent work on the basal monotreme mammals has completely changed our conception of how and when this change occurred. Platypus and echidna lack SRY, and the therian X and Y are represented by autosomes, implying that SRY evolved in therians after their divergence from monotremes only 166 MYA. Clues to the ancestral mechanism usurped by SRY in therians are provided by the monotremes, whose sex chromosomes are homologous to the ZW of birds. This suggests that the therian X and Y, and the SRY gene, evolved from an ancient bird-like sex chromosome system which predates the divergence of mammals and reptiles 310 MYA.
AB - Therian mammals (marsupials and placentals) have an XX female: XY male sex chromosome system, which is homologous to autosomes in other vertebrates. The testis-determining gene, SRY, is conserved on the Y throughout therians, but is absent in other vertebrates, suggesting that the mammal system evolved about 310 million years ago (MYA). However, recent work on the basal monotreme mammals has completely changed our conception of how and when this change occurred. Platypus and echidna lack SRY, and the therian X and Y are represented by autosomes, implying that SRY evolved in therians after their divergence from monotremes only 166 MYA. Clues to the ancestral mechanism usurped by SRY in therians are provided by the monotremes, whose sex chromosomes are homologous to the ZW of birds. This suggests that the therian X and Y, and the SRY gene, evolved from an ancient bird-like sex chromosome system which predates the divergence of mammals and reptiles 310 MYA.
KW - Evolution
KW - Mammalian sex determination
KW - SRY
UR - http://www.scopus.com/inward/record.url?scp=53849094422&partnerID=8YFLogxK
U2 - 10.1007/s00018-008-8109-z
DO - 10.1007/s00018-008-8109-z
M3 - Review article
SN - 1420-682X
VL - 65
SP - 3182
EP - 3195
JO - Cellular and Molecular Life Sciences
JF - Cellular and Molecular Life Sciences
IS - 20
ER -