Athens, Ga. – When it comes to picking a mate,
Crosby, Stills, Nash and Young had an answer: “If you can’t be with the one you
love, love the one you’re with.” As it turns out, that may be a cardinal rule
in the animal kingdom, too.
New research that crosses several species boundaries shows
that when animals must choose less-than-preferred (to them) mates, females and
males apparently have ways to compensate that increase the chance their
offspring will survive. The study, just published in the Proceedings of the National Academy of Sciences, adds weight to the
Compensation Hypothesis, a proposal that has given insight into how individuals
can pass on their genes even under less than ideal circumstances.
“It’s always better for offspring if parents can mate with
preferred partners, but it’s becoming clear that when parents can’t have that
preferred partner, they have ways of making up for it,” said Patricia Adair
Gowaty, a Distinguished Research Professor of Ecology and Genetics at the
University of Georgia and lead author of the study. “When female ‘choosers’
were in enforced pairs with males they did not prefer, they laid more eggs.
Similarly, when males are paired with females they do not prefer, they
ejaculate more sperm. This compensation seems to be a way of making the best of
a bad job.”
Co-authors of the paper were Wyatt Anderson, Alumni
Foundation Distinguished Professor of Genetics, and Yong-Kyu Kim, an assistant
research scientist in Anderson’s lab, both at UGA; Cynthia K. Bluhm of the
Delta Waterfowl and Wetlands Research Station in Canada; Lee C. Drickamer of
Northern Arizona University; and Allen J. Moore of Centre for Ecology and
Conservation at the University of Exeter in the United Kingdom.
One of the new study’s strongest arguments for the
Compensation Hypothesis is that it includes experimental results in Tanzanian
cockroaches, fruit flies, pipefish, wild mallards and feral house mice. When
each species faced experimental constraints on free expression of their mate
preferences, individuals found ways around the predicament that could improve
the chances that offspring could survive and perhaps even flourish.
“Just how an individual finds its best mate isn’t really
known,” said Gowaty, “though there’s some evidence that he or she may be somehow
sensing the advantage of the potential mate’s immune system in relation to the
chooser’s own.” She points out that many factors are probably at work,
including behavioral cues and what potential resources a mate may bring.
While the strategies for dealing with nonpreferred mates can
help offspring, advantages for the mating pairs themselves are less clear. In
experimental situations, for example, females mated to non-preferred males
didn’t live as long as females mated to their preferred choice.
One interesting aspect of the study is its implication that
all individuals in a species have a flexible response to such problems as
constraints on expression of their mating preferences. If that’s true, it hints
that compensation may evolve—which could add an unexpected wrinkle to the story
of natural selection.
“How compensation evolves is crucial,” Anderson said.
The issues at stake are, in fact, even broader.
“The study also has implications for conservation because it
suggests that the best way to keep species alive may be, if possible, to let
individuals choose their own mates,” said Gowaty.
The Compensation Hypothesis is Gowaty’s work and was first
published only four years ago, though she has been working on it for more than
a decade.
Just how—and if—the hypothesis works in humans remains
unknown, since studying the subject remains practically (and ethically)
improbable. Still, the idea remains a deep part of popular culture.
When Mick Jagger sings “You can’t always get what you want,”
most of us nod. And then we start to plot a way around the problem.
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Note to editors: Copies
of the paper are available from Gowaty. Please e-mail her at the address at the
top of this release.
