Climatic adaptations and distributions in theDrosophila takahashiispecies subgroup (Diptera: Drosophilidae)

Abstract

Among subtropical species of the Drosophila takahashii species subgroup, temperature adaptations were related to altitudinal distribution; D. trilutea was adapted to lower temperature and occurred at high altitudes in September in Taiwan, D. takahashii was adapted to higher temperature and occurred mainly at low altitudes, and D. prostipennis was adapted to an intermediate range of temperature and occurred at mid to high altitudes. A temperate species, D. lutescens, was adapted to a wider range of temperature than the subtropical species: it was more cold-hardy than all three subtropical species and more heat-tolerant than D. prostipennis and D. trilutea. The temperature ranges encountered in the temperate region far exceed the range in subtropical areas, and this is likely to be reflected in the temperature adaptations of these temperate and subtropical species. D. lutescens has a photoperiodically controlled reproductive diapause. No latitudinal cline was observed on cold-hardiness of D. takahashii. By contrast, cold-hardiness and photoperiodic response differed between northern and southern populations of D. lutescens.