Abstracts (first author)
Can reproductive barriers maintain differentiation in face of global changes? A case study in Drosophila subobscuraPDF
Species with wide distributions may be highly differentiated across contrasting environments. While gene flow may help maintain similarities among populations, local adaptation may lead to their divergence, as well as promote reproductive isolation, further fostering evolutionary diversification. The interplay between these two processes is of major importance for Conservation, as it will determine if populations differentiate or become more similar in the long run, as a result of environmental changes such as those imposed by man. In Drosophila subobscura, populations are differentiated along a latitudinal gradient, but recent evidence indicates that northern populations are becoming more similar to southern ones. An important issue is how much populations from the extremes of the cline differ in mating preferences, as this might contribute to reduce genetic introgression when populations meet. To address this, we analyzed the evolutionary dynamics of reproductive isolation of D. subobscura populations derived from the extremes of the European cline, while adapting to a common, laboratorial environment. We show that mating performance increased during laboratory adaptation. In general northern populations had a better performance than southern ones, and this difference was sustained across generations. Moreover northern females preferred mates from their own populations while southern females preferred males from the north. The assortative mating of the northern populations was stable through time, while disassortative mating of the southern populations faded away during laboratory evolution. Overall this study suggests that reproductive barriers may slow down the genetic introgression due to migration to the north, an important finding in evolutionary and conservation terms.