Starvation and desiccation tolerances in Drosophila: Comparison of species from different climatic origins

During their evolutionary history, drosophilids have been able to adapt to very diverse climatic conditions. To help explaining their geographic distribution and possibly also their cosmopolitan or endemic status, 22 species (24 strains) were investigated for their tolerance to starvation and to desiccation. Three other traits were also measured, ie., fresh weight, water content and lipid content. For most traits, a major difference was found between temperate and tropical species, while the biogeographical status was not important Temperate species, on average, were heavier, with more lipidic reserves and better resistance to starvation and desiccation. When the complete set of 24 strains was considered, positive correlations were found between most traits, and a negative correlation between water and lipid content. On the other hand, when the two geographic groups (tropical versus temperate) were considered separately, the correlations tended to decrease and even disappear among the less variable tropical species. Among temperate species, positive correlations were still significant between starvation and desiccation tolerance, and between lipid content and each tolerance.