Male mollies nip both sexes to improve their chances of mating
Female fish are attracted to males that "flirt" with other males, a study has found.
Scientists in
Germany studied the
behaviour of
tropical fish Poecilia mexicana, known as
Atlantic mollies.
The
female fish are known to "
mate copy" - preferring to
mate with
males they have seen
interacting sexually with other
fish.
Researchers found that
females still took an
interest in
males when their
flirtations were with the
same sex.
Dr David Bierbach from the
University of Frankfurt, Germany,
led the
research that is
published in the
Royal Society journal Biology
Letters.
In the
paper,
researchers refer to
homosexual behaviour in the
animal kingdom as a "conundrum".
"Male homosexual behaviour can be found in
most extant classes across the animal kingdom, but represents a
Darwinian puzzle as same-sex mating should decrease male reproductive
fitness," they wrote.
However, many
animals that engage in
homosexual behaviour
have also been observed
mating with the
opposite sex, including
penguins
and
bonobos.
Females choose their mates in molly society
Biologists have suggested that such
actions could still reap
genetic rewards, despite the perceived lack of
reproduction, through
knock-on
effects.
For
Atlantic molly males "
nip" near the
genital openings of potential
mates to signal their readiness to
mate.
Scientists have suggested that such
behaviour helps to
demonstrate the quality of
males, because their level of
exertions can
indicate overall
health and
virility.
Yet subordinate
males are known to nip both
females and other
males.
Studies of the
fish, which are found from
Mexico to
Guatemala, have shown that they can discern the
sexes based on
pheromones and
visual cues, undermining any
theories of
misrecognition.
So, in order to understand the motivations behind this
behaviour, the
German scientists studied
Atlantic mollies in their
lab.
Using animated recordings, the team
tested how "
attractive" the fish found different
examples.
While the
females found a colourful
male more
attractive than
a drab counterpart when swimming side by side, they
reacted better to
"less
attractive"
males once they had observed them
nipping either
males
or
females.
"We were quite surprised to find out that observed
homosexual
interactions had the
same influence on
females'
preferences as
heterosexual interactions," explained
Dr Bierbach.
"The implications are that
sexual activity per se is a trait
used by
females to evaluate
males' quality and that our
results could
also be true in other species."
The
scientists speculate that it could be a tactic
employed
by smaller,
subordinate - and thus less
attractive males - to
win more
female attention.
"
Males can increase their
attractiveness towards
females by
homosexual interactions, which in turn increase the likelihood of a
male's
future heterosexual interactions,"
Dr Bierbach told
BBC Nature.
"We do not know how widespread
female mate choice
copying is,
but up to now it is reported in many species, including
fruit flies,
fishes,
birds and
mammals [including]
humans."
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