[ASC-media] ANU MEDIA RELEASE: MORE SEX FOR MUMS LEADS TO HEALTHIER BABIES

Jane O'Dwyer jane.odwyer at anu.edu.au
Thu Nov 2 00:48:43 CET 2006


ANU MEDIA RELEASE
News from The Australian National University
 
THURSDAY 2 NOVEMBER 2006
MORE SEX FOR MUMS LEADS TO HEALTHIER BABIES: STUDY
Promiscuous females are more likely to give birth to healthier
offspring, researchers at The Australian National University have found.

The team based at the School of Botany and Zoology (BoZo) at ANU has for
the first time proven that promiscuity increases the survival rate of
offspring in an animal species. The findings were published in the
latest edition of Nature.

"Scientists have developed many theories to explain why some female
animals have multiple sex partners: whether it's trading sex for food
and protection, dealing with infertile males, or avoiding the negative
effects of inbreeding in species that can't recognise their relatives,"
team leader Dr Diana Fisher said.

"Another theory is that mating with multiple males would result in sperm
competition. This means that males with the strongest sperm are more
likely to become sires and father better quality offspring. Until now,
this theory hasn't been demonstrated convincingly."

The researchers found the first compelling evidence for this sperm
competition theory among brown antechinuses. These are mouse-sized,
insect-eating marsupials that are common in the forests of south-eastern
Australia. They are rarely seen, because they are quick, nocturnal, and
nest in tree hollows. 

The team brought male and female antechinuses into captivity for the
mating seasons in two successive years. Some females were only allowed
one mate, while others had three. Groups of three males were mated (one
at a time) with three different promiscuous females, so that paternity
tests could reveal their success at sperm competition. 

"In one year, we released families back into the wild when the babies
were still in the mother's pouch," Dr Fisher said. "The result was that
survival of babies with promiscuous mothers was almost three times as
high as those in the monogamous group."

"The next year, we kept families in captivity until the babies were
almost weaned. Again, babies of promiscuous mothers did much better.
Paternity tests showed that the sperm of some males were far more
successful than others, and, most important of all, that babies fathered
by these males were twice as likely to survive."

The research team also included Professor Andrew Cockburn, Mike Double
and Michael Jennions from BoZo, and Simon Blomberg from the Centre for
Resource and Environmental Studies at ANU.

More information: Dr Diana Fisher 02 6125 5651   
 
ANU Media Office: Simon Couper 02 6125 4171, 0416 249 241


Jane O'Dwyer
Media Manager
The Australian National University
T: 02 6125 5001
F: 02 6125 8255
M: 0416 249 231
W: www.anu.edu.au/media

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