Abstracts (first author)
Vanishing chromosomal inversion clines in Drosophila subobscura from Chile: is behavioral thermoregulation to blame?
Chromosomal inversion clines paralleling the long standing ones in native Palaearctic populations of Drosophila subobscura evolved swiftly after this species invaded the Americas in the late 1970s and early 1980s. However, the new clines did not consistently continue to converge on the Old World baseline. Our recent survey of Chilean populations of D. subobscura shows that inversion clines have faded or even changed sign with latitude. Here we investigate the hypothesis that this fading of inversion clines might be due to the Bogert effect; namely, that flies’ thermoregulatory behavior has eventually compensated for environmental variation in temperature, thus buffering selection on thermal-related traits. We show that latitudinal divergence in behavioral thermoregulation has evolved in Chile for females, with higher latitude flies having a lower mean of thermal preference. Plastic responses in thermal preference also lessen latitudinal thermal variation because flies developed at colder temperatures prefer warmer microclimates. Our results are consistent with the idea that active behavioral thermoregulation might buffer environmental variation and reduce the potential impact of thermal selection on other traits as chromosomal arrangements.