Temperate but not tropical Drosophila species maintain high fertility after long-term cold exposure: evidence for reproductive diapause?

MENSCH, J; HURTADO, J; ZERMOGLIO, P; DE LA VEGA, G; ROLANDI, C; SCHILMAN P.E.; MARKOW, T; HASSON, E

Simposio; 6th International Symposium on the Environmental Physiology of Ectotherms and Plants (ISEPEP6); 2015

Diapause consists of a distinct physiological state characterized by arresteddevelopment, enhanced stress resistance and metabolic changes in response tounfavorable environmental conditions. Although a wide variety of animals exhibit such adaptive phenotypic plasticity across seasons it is not clear to what extent the genetic and environmental mechanisms underlying diapause are conserved across insect taxa. We initially determined and compared the environmental conditions for cold-induced arrest of reproduction in four closely related fly species, two temperate and two tropical cactophilic South American Drosophila. Subsequently, we established that only the two temperate species appear to experience winter conditions require for arrest of maturation. Based on these findings, we predicted that only temperate species would show adaptations in terms of energy metabolism, cold tolerance and fitness after longterm cold exposure, as they are the only ones that evolved the capacity to undergo reproductive diapause. Our comparative study revealed both shared and distinct features between tropical and temperate species subjected to long-term cold exposure. On one hand, we found similar energy metabolism across species during cold exposure. On the other hand, not only were temperate species more fertile and fecund after cold exposure, but their cold tolerance also was superior. These findings highlight the role of thermalinducedreproductive plasticity as an integrated mechanism of cold adaptation in temperate South American Drosophila.