Competing suitors affect fertility of female chimps

Male chimpanzees compete quite fiercely - and in great numbers - for the attention of the female who might bear their offspring, but in the process they end up lowering the chances of the female to conceive, a study shows.

The contested female may have little choice than to tolerate the attentions of these would-be suitors, as mating with many males ensures that their young are not killed by jealous males.

However, all this harassment and jealous guarding by males can influence the ability of females to feed which is associated with their ability to conceive.

"Reproductive tactics of male chimps could put a damper on the ability of the female members of their species to conceive," said lead researcher Melissa Emery Thompson from the University of New Mexico in the US.

For the study, the researchers spent more than 11 years observing the daily interactions and diets of 50 members of the Kanyawara community of East African chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park in Uganda.

The researchers found that the more males gathered around a cycling or lactating female during a given month, the lower were her C-peptide (a by-product in the synthesis of insulin) levels.

Declining C-peptide levels, meaning that the female is spending more energy than she consumes, result in weight loss.

In this study, C-peptide levels also predicted production of ovarian steroids, indicating an effect on reproductive ability.

"This has significant downstream effects on females' reproductive functioning and fertility rates," Emery Thompson pointed out.

The study appeared in the journal Behavioral Ecology and Sociobiology.