Females tend to have more sexual partners in colder climates

Females tend to have more sexual partners when they live in colder climates and are happier being monogamous when it is hotter, a study has found.

The researchers, however, found that while the environment and temperature does have some influence, sexual behaviour is largely determined by an individual's genes.

"These results are an important step towards understanding how genes and environment contribute towards behaviour and ultimately how behaviour affects the success or failure of natural populations," said lead researcher Michelle Taylor from University of Exeter in England.

Previous research has shown that there are both monogamous and promiscuous females in all sorts of species including birds, reptiles and fish.

In this study into behaviour, reproduction and temperature, the researchers collected wild fruit flies from the hot climate of Arizona and cold climes of Montana in North America and observed their behaviour in a laboratory at the University of Exeter's Penryn campus in Cornwall.

They preserved a 'snapshot' of the genes available in the population by inbreeding flies for over 40 generations and then examined how many male partners each inbred female would accept when living at temperatures that were either warmer or cooler than their natural habitat.

The researchers found that more females accepted more partners when living in colder conditions, while more remained monogamous in hotter conditions.

However, some females were always more likely to have more male partners than others even when living at conditions very different to their original habitat.

The findings demonstrated that although temperature can encourage females to change their behaviour, ultimately the genetic background of each female remains the most important factor when predicting how many male partners a female will have in her life.

The study was published in the journal Behavioral Ecology.