The effect of the chromosomal location of the male-determiner on mating success in house fly


Sex determination is the molecular process that leads to the development of either a male or a female. Some species are polymorphic for how sex is determined. We do not have a good understanding of why this variation in the initiation of sex determination exists. The house fly, Musca domestica, is a modelorganism for studying the genetics and evolution of polymorphic sex determination. The male-determining Mdmd gene can be found on the Y chromosome (YM) and third chromosome (IIIM). Males carrying IIIM are found in southern regions where average temperatures are warmer. Males with YM are found in northern regions where average temperatures colder. We therefore hypothesize that the IIIM chromosome carries genetic variants that are “warm-beneficial” and YM has “cold-beneficial” variants. Our goal is to determine if there is a temperature-dependent difference in mating success between males with YM and males carrying IIIM. We conclude that male mating success is unlikely to be a trait that explains the geographic distribution of YM and IIIM in natural populations.