Meeting Abstract
Temperature can directly affect ectotherm life cycles, especially development. Ectotherms at high altitudes/latitudes experience cold temperatures and short growing seasons, and must develop quickly given seasonal time constraints. Ectotherms living at high altitudes/latitudes often have high metabolic rates relative to related organisms from lower altitudes/latitudes, a pattern termed metabolic cold adaptation. Because high metabolic rates are often positively correlated with high growth rates, the need to develop quickly in seasonally constrained habitats, a pattern termed countergradient variation, is often considered to be the major selective factor driving the metabolic cold adaptation. However, selection for high metabolic rates in seasonally constrained habitats is likely multifarious and driven by factors beyond growth rates and development time. In previous work we have shown that artificial selection for fast recovery from chill coma, a trait that should also be under selection at high altitudes/latitudes, also drives the evolution of higher metabolic rates across lines of the fly Drosophila melanogaster. Here we test whether selected lines with faster recovery from chill coma and higher metabolic rates also have faster development times and higher growth rates by rearing flies from egg to adult at four different temperatures (15, 20, 25, and 29oC). Our work suggests that to understand the evolution of altitudinal/latitudinal patterns in life history traits such as growth rates and development times, one must also consider how selection on other traits, like hardiness to short-term cold exposures that are also frequent at high altitudes/latitudes, may facilitate or constrain life history evolution.
