快猫短视频

MALES that flash flirty signals at females aren鈥檛 necessarily boasting about
their sexual prowess. In some fish, males may be conveying information about the
safety of their surroundings, coaxing the females into feeling relaxed enough to
mate.

Males are known to use courting to signal the quality of their genes, but
when marine biologists Bob Warner from the University of California in Santa
Barbara and Lawrence Dill of Simon Fraser University in Burnaby, Canada, studied
a Caribbean reef fish called the bluehead wrasse (Thalassoma
bifasciatum), this explanation didn鈥檛 make sense. 鈥淔emales tend to be quite
faithful,鈥� says Warner. 鈥淏ut the male courts her assiduously every time. There
is no information transfer going on about the quality of the male, because it is
the same male each time.鈥�

Male wrasse court females using white patches on their sides, which vary in
size between individuals. The patches not only catch the females鈥� attention,
they also make males more obvious to predators in open water. She watches him
from the security of the reef, joining him only if she is convinced it is
safe.

Warner and Dill noticed that while bright males never courted as long as the
dull fish, they were just as successful at mating. They wondered if the females
could be using the display to assess the risk of being eaten by a predator. 鈥淚f
a female goes for a dull male, she won鈥檛 have any information. It is inherently
more risky,鈥� says Warner. 鈥淏ut if a bright male is still alive, it must be
safe.鈥� The researchers tested their idea by putting model predators in the water
near the mating sites. The males soon got used to the fakes, but newly arriving
females thought there was a threat, and needed more courting by males before
they could be persuaded to mate.

Animal ecologist Matthew Evans from Stirling University says the idea is
鈥減erfectly plausible鈥�, although he advises caution when interpreting the
experiment. 鈥淵ou can鈥檛 know what鈥檚 going on in the mind of a fish,鈥� he says. But
Warner believes the strategy may prove to be common to other species where
females mate many times during their lives. 鈥淓ach individual mating event is
relatively unimportant to the female鈥檚 overall reproductive success. So she has
to make sure she survives from one reproductive event to another. The quality of
the male is much less important,鈥� he says.