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Selection experiments with Drosophila have revealed a possible evolutionary trade-off between cold resistance and starvation resistance that may be controlled by lipid metabolism. To test this trade-off in naturally occurring Drosophila simulans populations, flies were simultaneously collected from two temperate locales experiencing contrasting seasons. Flies from a tropical locale served as a control. Cold coma recovery, starvation resistance and lipid proportion were assayed on adult males and females from each locale. Compared with the summer-collected flies from Canberra, the winter-collected flies from San Diego recovered from cold coma more quickly, were less starvation resistant and had lower lipid levels. These results support an evolutionary trade-off between cold resistance and starvation resistance. Combined, these data also suggest that differences in lipid metabolism may be an underlying mechanism for this trade-off.

Systematic analysis of 12S ribosomal RNA sequences supports the proposal that adults of Austrosimulium pestilens Mackerras and Mackerras and A. bancrofti (Taylor) s.l. may be distinguished by antennal segment number. However, there were too few informative positions within the region sequenced to resolve the phylogenetic affinities of the distinct cytological forms within A. bancrofti s.l. These data demonstrate that 12S rRNA can aid phylogenetic resolution of blackfly morphospecies but not cytological forms.