TALLAHASSEE, Fla. When it comes to choosing a mate, female guppies don't care about who is fairest. All that matters is who is rarest.
Florida State University Professor Kimberly A. Hughes in the Department of Biological Science has a new study just published in the journal Nature that is the first to demonstrate a female preference for rare males using an experiment in a wild population, rather than a laboratory setting.
This study of genetic differences in male guppies is relevant to understanding variation in humans as well as in other organisms, Hughes said.
Hughes and her longtime collaborators studied guppies in Trinidad and found that male guppies with rare color patterns mated more and lived longer than the common males. The males' color variations are genetic and not due to diet or temperature. And the males' actual appearance didn't matter to the females, who are tan in color and do the choosing of mates.
"No matter which color pattern we made rare in any group, they mated more and had more offspring," Hughes said.
So, a male guppy common in one grouping, i.e., placed in a stream with many fish that look like him, is a dud to the females also in the stream. But, take that common male and place him in a different stream with only one or two others similar to him, and he's suddenly rare and a desirable mate.
In an earlier study, Hughes showed that male guppies with rare color patterns had a survival advantage compared to those with common patterns in natural populations. During a three-week study, also in Trinidad, 70 percent of common males survived, while 85 percent of rare males survived.
This new study, "Mating advantage for rare males in wild guppy populations," reports the results of paternity analyses of the offspring produced by the females in that earlier field experiment.
Hughes approached this new, rare-male-as-mating-champ theory with the goal of ruling i
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Florida State University