From Carrie Arnold at Nature:
“This bird acts like it has four sexes,” says Christopher Balakrishnan, an evolutionary biologist at East Carolina University in Greenville, North Carolina, who worked with Tuttle and Gonser. “One individual can only mate with one-quarter of the population. There are very few sexual systems with more than two sexes.”
The work helps to explain a long-standing puzzle for biologists. It shows how two identical chromosomes can evolve into distinct subtypes that can define the sexes of a species and their different behaviours. “These birds are an amazing system,” says Catherine Peichel, an evolutionary ecologist at the University of Berne. “The process of sex-chromosome evolution tends to erase much of the evidence of how it happened, so being able to watch the process in action is a huge benefit.”More.
As so many species remain unstudied, don’t count on their system to be unique. Or the only unusual one. That’s what happens when we get more information. Dogma is becoming a troubled industry.
See also: Y chromosome arose independently twice at same time, 180 mya
Genes on the Y chromosome a must for male survival (The Y chromosome had been reprieved earlier from its status as a vestige about to disappear, but this is newish)
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