Tuesday, 31 January 2012
Quality sperm production `is pricey for males
If you think sperm production comes cheaply to males, think again. Contrary to traditional view, it`s quite pricey, says a new study.
An international team has shown that the production of sperm is more biologically taxing than previously thought, and expending energy on it has significant health implications, the `PLoS ONE` journal reported.
In their study, the researchers investigated the trade-off between sperm quality and immunity in the Australian cricket, Teleogryllus oceanicus, to prove that the production of quality sperm is expensive and males are strategic about investing energy in the biological process.
"It is typically thought that females must invest heavily into reproduction, whereas males can freely produce millions of high-quality, tiny sperm on demand, with few costs.
"Here we show that the costs are in fact large, and these costs dictate how much effort a male will devote into any given sexual encounter," Damian Dowling of Monash University, who led the study, said.
In the study, the crickets were housed either with sexually immature females, sexually mature females incapable of reproduction, or sexually mature females capable of reproduction. Sperm quality was measured twice and immune function once during the experiment.
Dr Dowling said the male crickets were more likely to produce high quality sperm when housed with sexually mature females with whom they could mate, indicating a strategic investment of energy.
The team also found production of quality sperm appeared to have a negative effect on the crickets` immune systems.
"Males that invested heavily in their sperm paid the price of being more likely to succumb to a bacterial infection. We are talking about how increased investment into the quality of the ejaculate corresponds with general reductions in immune function," Dr Dowling said.