September 4, 2017
A recurring theme in nature
documentaries is that of choosy females selecting brightly colored males. A new
study shows that, in monogamous mating systems, male birds may select their
lifelong mates in much the same way.
Some traits, such as the tuft of
feathers atop a crested auklet, signal attractiveness to the other sex and
competitive rank within the same sex. Research has traditionally focused on
male competition for access to females or territory and on
females choosing males based on their feathers and fights. But recent
investigations suggest that females not only compete with each other, but also
rely on such traits in deciding whether to engage or defer. Accordingly,
"the idea has been floated that these traits could then become preferred
by males," says Omidyar Fellow Caitlin Stern, "because they indicate
that a female is successful in competing for resources."
To find out, Stern created
population genetic models involving females with or without a given trait and
males with or without a preference for it. "It has historically been a
challenge to understand how mating preferences for ornamental traits can evolve
when every individual succeeds in getting a mate," Stern explains, in part
because the seemingly simple selection process of monogamous pairs, where mates
couple up and remove themselves from the broader gene-swapping pool for good,
is tricky to handle mathematically. Nevertheless, over thousands of
generations, both the female trait and male preference persisted in the
population, suggesting that both are favored.
No comments:
Post a Comment