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Following article was
published by Oregon State University. Later on, it was published on
Science Daily and other medias.
Male Courtship
Pheromone Identified
09-16-99
By David Stauth, 541-737-0787
SOURCE: Lynne Houck, 541-737-4353
CORVALLIS, Ore. - University
researchers have discovered one of the first pheromones in a
vertebrate animal species that is produced by the male and helps him
when courting a female, in this case making her more calm, receptive
to mating and less apt to run away.
The study, to be reported Friday in
the journal Science, was done with a species of terrestrial
salamander called Plethodon jordani. But, as scientists learn more
about this mysterious world of chemical communication, it seems
likely that there may be many other pheromones that affect behavior
and mating in many animal species, including humans.
"It's very unusual in nature to find
a pheromone that male vertebrates use in courtship and mating," said
Lynne Houck, an associate professor of zoology at Oregon State
University and co-principal investigator on the study, along with
colleagues at the University of Chicago and University of
Louisville. "Usually you find these types of pheromones only in the
female."
The researchers in this case
identified the pheromone, a single protein component that affects
the female, and the gene that is responsible for production of that
protein. Of considerable interest, Houck said, is that this gene is
similar, although not identical, to one found in humans.
In salamanders, the courtship and
mating process is odd.
"Terrestrial salamanders aren't
always wildly enthusiastic about mating, and there are only a few
weeks or months of the year that the female will even consider the
idea," Houck said. "And, during that time, the chances of her mating
with a male are considerably reduced if he doesn't produce this
particular pheromone."
In that process, one part of which is
called a tail-straddling walk, the male deposits pheromones from a
gland under his chin - a gland which only becomes active during
mating times - onto the female's nose.
Repeated deposits of this chemical
seem to soothe the female, make her more receptive to mating and
also more inclined to do it quickly, speeding up a process that can
take 45 minutes or more and expose both the animals to other
dangers. And the process is discreet, not readily apparent to other
salamanders who may wish to compete for a mate.
In an unusual reproductive process,
the female salamander then stores the sperm deposited by this male
and uses it at some point weeks or months after insemination to
fertilize her eggs. The benefit of this time delay between mating
and egg laying is that the female can search for a very secluded
place that is just large enough for her and her eggs. The female
will stay with her eggs for about four months, guarding them against
predators.
Pheromones are increasingly being
studied by researchers for the key roles they play in species
recognition, reproduction and other behaviors. Pheromones have
commonly been identified for many insects, but less so for
vertebrate animal species.
However, Houck said, there is some
clear evidence of their operation in humans. Research has shown that
female humans who spend a great deal of time in one another's
company often send out chemical signals that help them synchronize
their menstrual cycles. And there's evidence that a woman who spends
much time around a single man develops a more regular menstrual
cycle, which might be conducive to successful conception.
"The sexuality of humans is obviously
pretty complicated and goes far beyond a single chemical cue," Houck
said. "But that doesn't preclude the possibility that in fact there
are some chemical cues at work which we don't yet fully understand."
http://oregonstate.edu/dept/ncs/newsarch/1999/Sep99/phero.htm
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