Male pregnancy and abortion:
The sex life of pipefish
A skinny little fish called the pipefish is high on the list of
wildlife oddities, for the male of the species is the one which gets
pregnant.
The fish is a close cousin of the seahorse and sea dragon, which also
carry developing embryos in a unique organ called a brood pouch into
which the female deposits her eggs during mating.
The male pipefish can carry between five and 40 offspring in its
transparent pouch, and nurtures them to term after a pregnancy lasting
between 12 and 14 days.
But a new study shows that the pipefish is more than a piscatorial
gender-bender.
It also chooses which of the brood survives, on the basis of the
mother's attractiveness.
Biologists Kim Paczolt and Adam Jones from Texas A&M University in
College Station, Texas studied consecutive broods brought to term by
male Gulf pipefish (Syngnathus scovelli).
They made a curious discovery: some pipefish were excellent dads and
other were deadbeats - and the key lay with the male's attraction to his
mate.
Male pipefish tended to seek out larger females for mating, the duo
found.
If they mated with a less ample female, they often selectively
aborted some of the embryos, apparently to save resources for future
reproductive opportunities.
"The bottom line seems to be, if the male likes the mum, the kids are
treated better," Kaczolt said.
"Why this occurs, we don't fully understand, but our findings are
quite specific about this relationship... If the male prefers the
female, he treats their mutual offspring better."
Kaczolt added: "It's almost as if he is saying, 'Are these babies
worth more effort?' If he is not overly fond of the mother, the answer
appears to be 'No,' and he invests fewer resources."
Genetic trade-offs and mating choices are commonplace as animals
strive to have offspring with the best possible chance of survival.
But this is the first time it has been observed after copulation in a
sex-reversed species, says the paper, published in the weekly British
science journal Nature.
Pipefish are widespread in warm sea waters. They grow to around 10 to
12 centimetres (four to five inches) in length and look rather like an
elongated version of the seahorse. AFP
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