The role of photoperiod in the biology of a desert didelphid: reproduction and energetics of male Thylamys pallidior

SÁNCHEZ DÓMINA, ROSARITO; SASSI, PAOLA L.; ALBANESE, SOLEDAD; RODRÍGUEZ, DANIELA; MENÉNDEZ, JOSEFINA

Perth

Congreso; 12th International Mammalogical Congress; 2017

Reproduction implies high energetic cost to animals; therefore it should be synchronized with most favorable season of the year. Photoperiod could act as a cue for regulation of reproduction in mammals from seasonal habitats. Thylamys pallidior is a marsupial inhabiting Monte desert from Argentina; it reproduces once in a life time synchronizing with high food resource seasons. However, only those individuals able to cope with winter conditions will reproduce. Our objective was to investigate the role of photoperiod as potential cue for the onset of reproduction and its effect on metabolism as an indicator of energetic performance. Males of T. pallidior were captured in the Monte Desert; five were maintained under natural photoperiod (NP) and five under constant LD 12:12 and 10:14 (winter; CP) for 12 months. We recorded body weight, tail and scrotal width, testes pigmentation and spermathorroea. Metabolic rate and changes in body temperature were measured on individuals from each treatment at different temperatures (5-38°C). We found no difference in scrotal related variables between treatments, individuals from NP showed spermathorroea 2 months earlier than CP. We found different patterns of tail width variation between treatments. No statistical difference was found for metabolic rates and body weight loss. However, NP animals showed decreases in body temperature and metabolic rate at the end of trails compared to CP. These tendencies seem to indicate some effect of photoperiod in regulating reproduction and in performance of animals under low temperatures. Further studies are necessary to explore and confirm these results.