Maternal investment and delayed feeding in neonatal Lake Erie watersnakes: a life-history strategy

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• 作者：Elizabeth W. Mack ; Jennifer L. Beck ; Kristin M. Stanford and Richard B. King
• 刊名：Journal of Zoology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：301
• 期：2
• 页码：150-156
• 全文大小：197K
• ISSN：1469-7998

文摘

Neonatal growth can have lasting consequences on survival and reproduction. In many taxa, larger, faster growing neonates experience higher survival, reach sexual maturity more rapidly, and achieve higher lifetime fecundity. In contrast to their closest relatives, Lake Erie watersnakes grow slower, mature later, and may delay feeding until after their first hibernation. To determine if Lake Erie watersnakes do indeed delay feeding until after their first hibernation, we compared age class 0 (between birth and first hibernation) and age class 1 (emergence from hibernation and through the first full season) snakes in the field and in the laboratory. In the field, only 0.6% of pre-hibernation neonates were found to contain prey, while 11.9% of post-hibernation neonates contained prey. During captive feeding experiments, the probability of eating was positively correlated with age (binary logistic regression, Wald χ12 = 25.354, P < 0.001). To clarify the underlying mechanism for delayed feeding, we compared neonatal yolk and fat reserves among species with delayed feeding (Lake Erie watersnakes, Graham's crayfish-eating snakes), species that commence feeding immediately after birth (common gartersnakes, Dekay's brown snakes) and a species falling between these extremes (queen snakes). Like Lake Erie watersnakes, Graham's crayfish-eating snakes contained large energy reserves (yolk + fat body mass to carcass mass ratio = 0.39 and 0.24, respectively), common gartersnakes and Dekay's brown snakes lacked measurable reserves (0.00), and queen snakes contained intermediate reserves (0.17). Taken together, this evidence suggests that neonatal Lake Erie watersnakes do delay feeding until after their first hibernation and contain large energy reserves at birth to facilitate this behavior. While most snake life-history studies have focused on the trade-off between offspring size and number, Lake Erie watersnake females invest large amounts of energy in offspring condition.