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Should Y stay or should Y go: The evolution of non‐recombining sex chromosomes
Author(s) -
Sun Sheng,
Heitman Joseph
Publication year - 2012
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.201200064
Subject(s) - biology , multicellular organism , evolution of sexual reproduction , chromosome , evolutionary biology , genetics , y chromosome , autosome , extinction (optical mineralogy) , x chromosome , gene , paleontology
Gradual degradation seems inevitable for non‐recombining sex chromosomes. This has been supported by the observation of degenerated non‐recombining sex chromosomes in a variety of species. The human Y chromosome has also degenerated significantly during its evolution, and theories have been advanced that the Y chromosome could disappear within the next ∼5 million years, if the degeneration rate it has experienced continues. However, recent studies suggest that this is unlikely. Conservative evolutionary forces such as strong purifying selection and intrachromosomal repair through gene conversion balance the degeneration tendency of the Y chromosome and maintain its integrity after an initial period of faster degeneration. We discuss the evidence both for and against the extinction of the Y chromosome. We also discuss potential insights gained on the evolution of sex‐determining chromosomes by studying simpler sex‐determining chromosomal regions of unicellular and multicellular microorganisms.