Recombination and Sexual Selection

Differences in recombination between males and females are well-known. There are many theories about the origin and evolution of these differences. In this article, we consider some of these theories and try to test one of them, the hypothesis of sexual selection. We examine recombination rate in the barn swallow and pale martin. These two swallow species are quite closely related and similar in lifestyle, but differ in sexual dimorphism. It is well-pronounced in the barn swallow, while it is almost impossible to distinguish males from females in the pale martin. The general level of recombination in female barn swallows is 13.5% higher than in males, while such sex differences are insignificant in the pale martin. It is likely that in the common ancestor of these two swallow species, males and females were similar both in morphology and in the recombination level. Then, sexual selection in barn swallows resulted in the sexual dimorphism in both these characters. However, the reason why the recombination increased in females rather than decreased in males is puzzling. Perhaps, it can be explained by the so-called runaway sexual selection.

recombination, sexual selection, heterochiasmy, meiosis, barn swallow, pale martin