Preference for related mates in the fruit fly, Drosophila melanogaster

Somewhat surprisingly, recent research predicts that some animals might actually have higher overall reproductive fitness if they mate with a relative. This theory is known as optimal inbreeding and is caused by the inclusive fitness benefits of inbreeding.

For a detailed explanation of optimal inbreeding see Stephen’s other research work (insert link to other blog) on assortative mating for relatedness in fruit flies. In that previous work Stephen found that flies from a wild population were mating with relatives more than expected by chance, as would be predicted under optimal inbreeding. However, some of the results from that study suggested that this increased relatedness between mating pairs was not actually caused by mate choice and more work would be required to see if this was likely to be an example of optimal inbreeding.

For this follow up study Stephen used a laboratory experiment on flies from the same population as the previous field study to see how the relatedness of a potential mate affects its attractiveness. Using a laboratory experiment has the advantage that mate choice can be looked at while other factors are controlled. Stephen used a crossing scheme to generate flies of various levels of relatedness. He then set up individual pairings and recorded how quickly a female would accept a male’s advances and mate, as well as how long the two mated for. Stephen found that females mated more rapidly with more closely related males. This is consistent with the theory of optimal inbreeding and suggests that mate choice could account for the increased relatedness seen between mating pairs in the previous study.

The results of these studies suggest that the theory of optimal inbreeding should be investigated further.

To read Stephen’s full article click here.

Dr Stephen Robinson is an Environmental Advisor/Zoologist with Terrestrial Ecosystems.