How does promiscuity in females impact evolution?

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Darwin’s original ideas about sexual selection were based largely on males competing for mates, either by fighting among themselves or by showing off fancy ornaments to attract choosy females. And it is indeed likely that sexual selection led to the evolution of stags’ antlers and male peacocks’ tails.

But when females are promiscuous, sexual selection gets even more interesting. If a female mates with different males in quick succession then the sperm of those males compete for the female’s eggs. This is one of the reasons that the males of many species have evolved to produce large numbers of sperm: they’re tickets in the fertilisation raffle.

Does more sex mean more species? Broadly speaking the view has been yes. More sex equals more selection, which equals rapid evolution and so more species.

Some past studies support these ideas and find female promiscuity is associated with higher speciation rates, although other studies find little evidence for this. However, a new study published in Evolution suggests the exact opposite. The data shows that in shorebirds, there are more subspecies (races) among monogamous species than among more promiscuous species. So what’s going on here?

 

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The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: What Is Promiscuity’s Effect on Evolution?

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