Based on an insect study conducted by researchers at the University of Exeter in the U.K., female fruit flies in colder climates are more promiscuous and are more likely to practice monogamy when living in a hotter climate.

Studying the relationship between reproduction and temperature, the researchers took wild fruit flies from Arizona (known for its hot climate) and Montana (known for its cold climate) to their lab located at the University of Exeter's Penryn campus in Cornwall.

The researchers inbred flies for more than 40 generations to preserve a "snapshot" of available genes to then see how many mates the inbred females would take on when living in either cooler or warmer temperatures compared with their natural habitat.

Published in the journal Behavioral Ecology, the researchers found that female fruit flies in colder climates did have more sexual partners then their warmer climate-living counterparts.

"This is a textbook example of the role of genes versus environment. Sexual behavior is really hardwired into females. It makes sense biologically for females to have a number of partners as they will produce more offspring that are more genetically diverse and survive better," lead researcher Dr. Michelle Taylor said.

However, the study found that the environment only had a partial influence on this behavior.

By exposing flies with certain genes (more specifically genotypes, or the individual's collection of genes) to different temperatures in the way that they did, the researchers were able to see how genetics affected their sexual behavior versus the environment.

And they uncovered that some female fruit flies preferred to stay monogamous, while others favored taking on multiple sexual partners no matter the temperature. That means that even though the temperature could influence promiscuous behavior, whether or not they chose to be monogamous ultimately came down to their genetic makeup.

"These results are an important step towards understanding how genes and environment contribute towards behavior and ultimately how behavior affects the success or failure of natural populations," Taylor said. "Mating with many different males can change the genetic make-up of a population because it increases the number of combinations of genes represented in each generation. Evolutionarily speaking, this could be one reason why some populations are able to adapt to changing environments while others go extinct."

Fruit flies are not the only monogamous creatures in the animal kingdom. Swans, French angelfish, wolves and gibbons all find one mate for life.


Photos:  Richard Sercombe | Flickr and Dominic Hart, NASA | Flickr

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