follow up to my holiday snap just sent
from ABC tv program 'Catalyst'
In 1990, ABC TV’s Quantum, took a glimpse into the secret life of the
Antechinus, a marsupial predator the size of a mouse.
Back then we learnt that the males make the ultimate sacrifice, giving their
life after a frenzy of copulation to pass on their genes.
But what’s in it for the females?
17 years on Catalyst catches up with Dr Diana Fisher to find out.
Genetic paternity tests show that the female Antechinus that sleeps around
produces much fitter offspring than those forced to be monogamous…
It seems for Antechinus at least, it pays to be promiscuous!
TRANSCRIPT
Geoff Burchfield: This is a marsupial mouse, known officially as Antechinus, but
it is a mouse in size only.
Dr Annemarie Watt: Well they are certainly not mouse-like, they are
insectivorous whereas mice are herbivorous, so unfortunately it just one of
those names, they are small and they are furry so they must be mice. I think we
should call them Antechinus, it’s a lovely name.
Geoff Burchfield: They live a hectic life chasing insects, spiders and the like,
they are rarely seen and rarely studied.
For awhile now a strange breeding ritual has been known, its been called big
bang reproduction because quiet literally all the males go out in a frenzy of
copulation.
Fighting between the males so intense and couplings are so furious that levels
of stress hormones rise high enough to destroy the entire immune system the
result all the males perish leaving the females to bring up the next generation.
Narration: That was 17 years ago…
Dr Paul Willis: This bizarre sex life needed some explaining, what’s in it for
the females? And what’s the best evolutionary strategy for a father who won’t be
around to see the kids grow up?
Narration: Recently this weird nocturnal life of Antechinus attracted the
attention of zoologist Diana Fisher.
Dr Paul Willis: A likely spot.
Dr Diana Fisher: This sort of litter on the ground and bark they love to forage
in there.
Narration: And her studies of Antechinus revealed something that wasn’t known
before, it pays for females to have plenty of male partners.
Dr Paul Willis: So Diana what did you actually do with the Antechinus?
Dr Diana Fisher: Well we wanted to do an experiment to see what would happen if
some of the females were forced to be monogamous…so what we did was brought them
in from here into captivity.
Narration: By forcing some females to be monogamous and some to be promiscuous
Diana was able to look at survival rates of the babies.
Dr Diana Fisher: Well the females that mated with multiple males had massively
better offspring survival. The females who were only allowed one had only about
20% of the babies survive. Whereas, 70% of the promiscuous females babies
survived! So that’s quiet an amazing difference.
Narration: Once the Antechinus female is loaded with the sperm from several
males, a sperm war erupts inside her.
Resulting in survival of the fittest sperm!
It’s the first time such a sperm war has been reported in mammals and for
Antechinus at least it seems that sleeping around is good for the girls and the
boys.
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