Harms Heidi K, Paitz Ryan T, Bowden Rachel M, Janzen Fredric J
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, 50011, USA.
Physiol Biochem Zool. 2005 Nov-Dec;78(6):996-1004. doi: 10.1086/432920. Epub 2005 Aug 26.
Theory predicts that in long-lived organisms females should invest less energy in reproduction and more in growth and self-maintenance early in life, with this balance shifting as females age and the relative value of each reproductive event increases. We investigated this potential trade-off by characterizing within-population variation in resource allocation to eggs by female painted turtles (Chrysemys picta) and relating this variation to their nesting ecology and life history. We examined lipid and protein allocation to yolks, accounting for both relative female age and seasonal effects (first vs. second clutches within a female). Older females appear to increase their investment in reproduction by producing larger eggs, but these eggs are not disproportionately more lipid or protein rich than the smaller eggs from younger females. Within the nesting season, first clutches have more lipid and protein than second clutches. We also found that younger females nest closer to the water than older females. Our results indicate that trade-offs involving resource allocation and nesting behavior do occur both seasonally and with age, suggesting ontogenetic variation in life-history strategies in this long-lived organism.
理论预测，在长寿生物中，雌性在生命早期应在繁殖上投入较少的能量，而在生长和自我维持上投入更多的能量，随着雌性年龄的增长以及每次繁殖事件的相对价值增加，这种平衡会发生变化。我们通过描述雌性彩龟（Chrysemys picta）在种群内对卵的资源分配变化，并将这种变化与它们的筑巢生态和生活史联系起来，研究了这种潜在的权衡。我们研究了脂质和蛋白质在卵黄中的分配情况，同时考虑了雌性的相对年龄和季节效应（雌性的第一窝卵与第二窝卵）。年龄较大的雌性似乎通过产出更大的卵来增加它们在繁殖上的投入，但这些卵并不比年轻雌性产出的较小的卵含有更多不成比例的脂质或蛋白质。在筑巢季节内，第一窝卵比第二窝卵含有更多的脂质和蛋白质。我们还发现，年轻雌性筑巢的位置比年长雌性更靠近水源。我们的结果表明，涉及资源分配和筑巢行为的权衡在季节和年龄上都确实存在，这表明这种长寿生物在生活史策略上存在个体发育的差异。
