Effect of winter-like conditions on survival and reproductive capabilities of two South American species of Drosophila

KREIMAN LUCAS; MENSCH, JULIÁN

Buenos Aires

Congreso; 8 International Symposium of Environmental Physiology of Ectotherms and Plants; 2019

During winter insects drop their abundance with a recovery at spring. Indeed, many species are unable to complete their life cycle under winter temperatures. Drosophila buzzatii and D. koepferae are sister species that inhabit desert areas of South America where winter temperature drop below their developmental thresholds and the critical temperature for reproductive maturation. The rationale of our work is that interanual persistency of both species rely mainly on overwintering adults, that not only survive but also remain fecund and fertile after the winter season. To test these hypotheses, both species where dispose at 10°C to evaluate the effect of cold on survival, fecundity and fertility. Likewise, periodic samples were taken during cold exposition to quantify the incidence of ovarian maturation during winter progression. Survival functions showed a rise on risk of death from the sixth week at 10°C. In this vein, we compared fecundity and fertility after the sixth week. To do so, two treatments were employed, one in which flies enter the cold as mated, and other where they were still virgins. The results showed a life expectancy at 10°C that triples that of 25°C. Particularly, virgin D. buzzatii shows a lower risk of dying at 10°C. Mated D. koepferae shows the lower fecundity and appears not to be fertile after a long exposure to winter-like conditions at any reproductive status. Our results showed that both species are able to survive the winter season and importantly to remain fecund. However, while D. buzzatii recovered fertility after cold recovery at both reproductive conditions, D. koepferae exhibits no reprodutive output, which contrasts with the persistence of the species in the wild. The effect of winter fluctuating temperatures will be explored in an attempt to explain this conflicting observations.