Reproductive Ecology of the Threatened Pitviper Bothrops insularis from Queimada Grande Island, Southeast Brazil
The Golden Lancehead (Bothrops insularis) is a critically endangered snake endemic to the Queimada Grande Island in southeastern Brazil. Here, we provide data on reproductive biology of B. insularis obtained in the field and from preserved museum specimens and compare our results with its mainland relative Bothrops jararaca. Similar to other Bothrops species, females of B. insularis attained larger body sizes than males, but the sexual size dimorphism (SSD) value is much lower than in B. jararaca. The seasonal timing of reproduction of B. insularis is similar to mainland B. jaracaca as well as other species of the genus Bothrops. Courtship observed in nature takes place in autumn and early winter (March to July); vitellogenesis occurs from summer to spring (March to December); ovulation and fertilization occur in early spring (September); embryonic development takes place in middle spring and summer (October to April); and recruitment of newborns is restricted to the summer (February and March). Both offspring size and offspring mass of B. insularis are similar to that observed in B. jararaca, but B. insularis produces a high frequency of atretic follicles. Apparently B. insularis has a lower reproductive frequency than B. jararaca, which is highly variable from year to year. The distinct reproductive traits of B. insularis (compared to B. jararaca) seem to be related to the ecological conditions of its insular environment, which may eventually be considered for the conservation management of this threatened species.Abstract
Annual distribution of mean monthly temperature (°C) and rainfall at Queimada Grande Island from 2007 to 2008. Lines represent mean temperature, and bars denote rainfall. Data were obtained from micro weather station installed in Queimada Grande Island during this study. The gap in May and November occurred because of the failure of the station.
Seasonal variation in diameter of largest ovarian follicles (or oviductal embryo) in adult females of Bothrops insularis. Solid circles = ovarian follicles; open circles = embryos or eggs without visible embryos in the oviducts.
Specimens of Bothrops insularis observed in the field in June 2007: female resting on the branch (upper left); one male moved toward this female (upper right); one male inspecting a female (lower left); this male rubbing his “chin” on anterior dorsum of the female (lower right).
Litter sizes (based on vitellogenic follicles) of Bothrops insularis (open circles) and Bothrops jararaca (solid circles) in relation to body size of the female.
Proportion of reproductive females of Bothrops insularis found during the reproductive period (between June and December) at Ilha da Queimada Grande, from 1995 to 2008.
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