Peculiarities of the Courtship Song in the Drosophila melanogaster Populations Adapted to Gradient of Microecological Conditions

In theory of evolution, two chief scenarios of development of sexual isolation-allopatric and sympatric, which act respectively under conditions of geographic separation or without it, are considered. Differences in the courtship behavior and in the used signals can lead to reproduction isolation and prevent gene exchange between sympatric populations or species, in which postmating barriers are absent. The previous studies of natural Drosophila populations inhabiting the opposite, ecologically contrast slopes of evolutional canyon (vicinities of the brook Oren in the mountain ridge Karmel, Israel) revealed statistically significant differences between them by the complex of adaptive and behavioral parameters including courtship behavior and choice of partner for mating. Astonishingly, differentiation of two populations has appeared in spite of a very small distance be tween two slopes. Here we report the statistically significant differences between males from the opposite slopes in characteristics of the courtship song that is one of signals serving for recognition by female of sexual partner of her species. We suggest that these differences can underlie the earlier revealed female discriminational behavior and can reflect different adaptive strategies in the populations inhabiting opposite canyon slopes.