Parents increase their fitness by investing resources in offspring. However, such investment is costly for parents, leading to trade-offs, which should shift towards heavier investment in reproduction as females age and future reproductive opportunities decrease. Nests of aquatic turtles laid farther from water have higher survival than those laid closer to shore because nest predators often forage along environmental edges. However, the predation risk of adult females increases farther from water because water is used as refuge from terrestrial predators. Thus, females may balance investment in current offspring versus maternal survival and future offspring. To test whether investment varies depending upon perceived risk, we exposed 30 painted turtles, Chrysemys picta, to simulated predation by capturing and handling them shortly after females chose a nest site. We then released females, which fled to water, and allowed them to return to land and nest undisturbed. We compared the distance to water of nests laid before and after simulated predation. Unexpectedly, females did not vary distance to water in response to simulated predation. Regardless, nest sites chosen after simulated predation were more likely to be depredated than those chosen before simulated predation, suggesting that females altered nest site choice in ways we did not quantify. In addition, although older turtles nested almost twice as far from water as younger turtles, we found no evidence that age influenced maternal response to simulated predation. Our findings suggest that perceived risk of mothers to predation influences nest site choice and subsequently reduces offspring survival in C. picta. In addition, we provide a rare assessment of how plastic maternal investment might vary across reproductive life.

中文翻译：

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风险敏感的母体投资：对野外巢址选择的亲子冲突评估

父母通过向后代投资资源来提高他们的健康。然而，这种投资对父母来说代价高昂，导致权衡取舍，随着女性年龄的增长和未来生育机会的减少，父母应该转向加大对生殖的投资。离水较远的水龟的巢穴比靠近岸边的水龟巢生存率更高，因为巢穴捕食者经常沿着环境边缘觅食。然而，离水越远，成年雌性的捕食风险就会增加，因为水被用作躲避陆地捕食者的避难所。因此，女性可以平衡对当前后代的投资与母体生存和未来后代的投资。为了测试投资是否因感知风险而异，我们暴露了 30 只锦龟，Chrysemys picta，通过在雌性选择巢穴后不久捕获和处理它们来模拟捕食。然后我们释放了逃到水中的雌性，让它们不受干扰地返回陆地和筑巢。我们比较了模拟捕食前后放置的巢穴与水的距离。出乎意料的是，雌性在模拟捕食时并没有改变与水的距离。无论如何，在模拟捕食后选择的巢穴比在模拟捕食前选择的巢穴更有可能被破坏，这表明雌性以我们未量化的方式改变了巢穴选择。此外，虽然年长的海龟离水的距离几乎是年轻海龟的两倍，但我们没有发现任何证据表明年龄会影响母体对模拟捕食的反应。我们的研究结果表明，母亲对捕食的感知风险会影响筑巢地点的选择，并随后降低 C. picta 中后代的存活率。此外，我们罕见地评估了可塑性母体投资在整个生殖生命中可能如何变化。