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

Abstract.

• 1 Resistance to desiccation and body size were studied in the drosophilid flies Zaprionus vittiger and Z.tuberculatus.
• 2 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.
• 3 No between-area differences were found for either body size or resistance to desiccation considered separately.
• 4 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.
• 5 It is concluded that differences of genetic organization have evolved between low and high altitude populations of Z.tuberculutus.
• 6 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.