The relation between body size and resistance to desiccation in two species of Zaprionus (Drosophilidae)

Abstract

Abstract. Resistance to desiccation and body size were studied in the drosophilid flies Zaprionus vittiger and Z.tuberculatus. Populations in a hot dry low altitude area were compared with those in a nearby cooler wetter high altitude area in the north‐eastern Transvaal of South Africa, using laboratory strains established from these populations. No between‐area differences were found for either body size or resistance to desiccation considered separately. However, in Z.tuberculatus, regression analyses using strain mean values showed a strong positive correlation between the two characters amongst strains derived from low altitude populations but not amongst strains derived from high altitude populations. It is concluded that differences of genetic organization have evolved between low and high altitude populations of Z.tuberculutus. From differences between species and sexes it is concluded that both body size and some unknown factor related to sex may influence resistance of desiccation.