Niche evolution and thermal adaptation in the temperate species Drosophila americana

The study of ecological niche evolution is fundamental for understanding how the environment influences species’ geographical distributions and their adaptation to divergent environments. Here we present a study of the ecological niche, demographic history and thermal performance (locomotor activity, developmental time and fertility/viability) of the temperate species Drosophila americana and its two chromosomal forms. Temperature is the environmental factor that contributes most to the species’ and chromosomal forms’ ecological niches, although precipitation is also important in the model of the southern populations. The past distribution model of the species predicts a drastic reduction in the suitable area for the distribution of the species during the Last Glacial Maximum (LGM), suggesting a strong bottleneck. However, DNA analyses did not detect a bottleneck signature during the LGM. These contrasting results could indicate that D. americana niche preference evolves with environmen...