Custos reprodutivos em Crotalus durissus (Serpentes, Viperidae) do Estado de São Paulo, Brasil.

Abstract

Reproduction is costly for both sexes, but the magnitude of spending and the relation to reproductive success differs substantially between males and females. Reproductive costs can be divided into two categories: costs associated with survival and energy costs. The costs associated with survival are those that affect the probability of survival of reproductive organisms. Costs associated with fertility influence the energy available for future reproductive event. Crotalus durissus has a seasonal reproductive cycle in which the beginning of the yolk deposition in ovarian follicles occur in the late summer, and mating occur in autumn, the sperm storage extends during winter the end of yolk deposition in ovarian follicles and fertilization occurs in spring. Finally, the birth is observed at the late summer. Males exhibit intraspecific competition evidenced in ritual combat with the purpose of access to receptive females release pheromones particles (vitellogenin) in the air. The inference of reproductive costs associated with survival was accomplished through surveys of activity rates between males and females, as na indicative of higher mortality risk. Females require a high energy investment to initiate the reproductive period. Lipids from the abdominal fat accumulates in the liver and are consumed during the cycle of ovarian follicles and this is the most costly phase of reproduction, when abdominal fat is shifted in yolk. The variation of the amount of abdominal fat and energetics substrates liver and kidneys were evaluated to measure the energy cost of reproduction in C. durissus. The results of this study shows that the reproductive strategies adopted by females Crotalus durissus require a high energy investment-evidenced by the higher levels of abdominal fat and lipids in the liver during vitellogenic phase, which are used to signal estrus in the reproductive season, ovulation and throughout pregnancy to nourish the embryos. Moreover, the pattern of activity differentiated between males and females reproductive tactics adopted by males during autumn, increase the rate of sighting, because during this season, the males perform a prolonged search by females, fighting and mating. For the pattern found in spring and summer, many females may be related to pregnancy and vitellogenic process, factors that increase body mass, and the thermoregulation rate, thus making them less able to escape predators, and then more sighted. During the winter, the result can be attributed to lower temperatures during this season, forcing males and females to remain in shelters to decrease moviments spending, given the ectothermic condition in reptiles.