Accelerating chill coma recovery time in a cold susceptible Drosophila by introgression and selection

MENSCH JULIÁN; SIMON HELGA; HURTADO JUAN; SCHILMAN PABLO; HASSON ESTEBAN

Tartu

Simposio; International Symposium of Environmental Physiology of Ectotherms and Plants; 2017

Environmental temperature is considered one of the most important abiotic factors influencing the geographic distributions of the species. In particular, the genus Drosophila represents a vast collection of organisms adapted to a wide variety of environmental temperatures resulting in marked interspecific differences in thermal tolerance. In this study, we focus on two South American species of the Drosophila buzzatii complex, D. borborema and D. koepferae, a chill susceptible and a cold tolerant species, respectively. Given that these species have the capacity to be crossed in the lab and produce fertile hybrids, we aimed to enhance chill coma recovery time in the cold susceptible species by introgression of genomic regions from the cold tolerant species followed by several generations of artificial selection. After 10 generations of artificial selection and back-cross at 25°C, some introgression lines reached a similar chill coma recovery time as the cold tolerant Drosophila. Based on these results, we tested whether introgression and selection for rapid chill coma recovery time affected the low critical temperature (CTmin), another popular and well-describe metric of cold tolerance. Interestingly, introgression lines maintained CTmin values of the chill susceptible species. Finally, we investigated how cold acclimation affect chill coma recovery time and CTmin. Cold acclimation improved cold tolerance of introgression lines, by lowering CTmin and accelerating chill coma recovery time. However, cold acclimated introgression lines showed similar CTmin and chill coma recovery time as cold acclimated chill susceptible species, hidden the differences found by selection under rearing conditions (25°C). Taken together, our results indicate that mechanisms that set the time to recovery from chill coma seems to be independent of the ones that control the low critical temperature and cold acclimation.