A comprehensive assessment of geographic variation in heat tolerance and hardening capacity in populations of Drosophila melanogaster from Eastern Australia

Abstract

We examined latitudinal variation in adult and larval heat tolerance in Drosophila melanogaster from eastern Australia. Adults were assessed using static and ramping assays. Basal and hardened static heat knockdown time showed significant linear clines; heat tolerance increased towards the tropics, particularly for hardened flies, suggesting that tropical populations have a greater hardening response. A similar pattern was evident for ramping heat knockdown time at 0.06-°C-min-1 increase. There was no cline for ramping heat knockdown temperature (CTmax) at 0.1-°C-min-1 increase. Acute (static) heat knockdown temperature increased towards temperate latitudes, probably reflecting a greater cap..