Evolutionary genetic research makes fly swatters superfluous

Are fly swatters soon to become a thing of the past? Up until now, researchers had not discovered the gene responsible for male development in any species of insect. However, they now appear to have made serious progress with the housefly. Evolutionary biologists from the University of Groningen are conducting this research with colleagues from their partner university in Göttingen. The results could be used to develop an ecofriendly way of controlling this pathogenic insect, and maybe other flies and mosquitoes too.

The sex of Dutch houseflies is determined in the same way as in humans: females have two X chromosomes and males have an X and a Y. The gene that determines masculinity is found somewhere on the Y chromosome. However, male houseflies in southern Europe do not have a Y chromosome. They have two Xs, and the gene controlling their masculinity is on one of the other five chromosomes, known as a neo-sex chromosome. Why this deviant strategy for determining gender developed is one of the questions to which the Evolutionary Genetics research group from the University of Groningen hopes to find an answer.

Important in terms of evolution

Head of research Leo Beukeboom explains: ‘In humans, the male gender is determined by what is known as the SRY gene. This gene evolved some 150 million years ago in the evolutionary line of mammals. Up until now, nothing of the kind has been identified in insects, but we are currently well on the way to pinpointing it in houseflies. The full DNA sequence of the housefly has already been determined so we are using this to measure the differences between male and female genes at different ‘Dutch’ and ‘Southern European’ temperatures. This evolutionally important study was recently awarded an Ubbo Emmius sandwich position with fellow biologists from the University of Göttingen.’

Ecofriendly control method

The research is not only an important step towards discovering how the mechanisms determining gender can change during the course of evolution. More knowledge of the genetics of sex determination in the housefly may also bring us closer to developing ecofriendly methods of controlling this pestilential insect. The partner university in Göttingen has already bred sterile male specimens of the harmful Mediterranean fruit fly. Breeding sterile male houseflies may constitute an effective method for controlling these pathogenic insects in the future.

Temperature

‘Previous research showed temperature to be the most important factor in determining the development of neo-sex chromosomes,’ continues Beukeboom. ‘However, we do not yet understand why these new sex chromosomes seem to have an advantage in warm climates over regular Y chromosomes in cooler areas. It’s possible that the gene for masculinity on the Y chromosome works less well in high temperatures. This would prompt a natural selection process favouring the new genes for masculinity, and could eventually lead to the development of new sex determination genes on other chromosomes.

Note for editors

More information: Prof. Leo Beukeboom, Evolutionary Genetics Department, Center for Ecological and Evolutionary Studies (CEES), University of Groningen, tel. +31 (0)50 363 8448 of 363 2092.