Becoming creatures of habit: among- and within-individual variation in nesting behavior shifts with age

The quantification of repeatability has enabled behavioral and evolutionary ecologists to assess the heritable potential of traits. For behavioral traits that vary across life, age-related variation should be accounted for to prevent biasing the microevolutionary estimate of interest. Moreover, to gain a mechanistic understanding of ontogenetic variation in behavior, among- and within-individual variance should be quantified across life. We leveraged a 30-year study of painted turtles (Chrysemys picta) to assess how age contributes to variation in the repeatability of nesting behaviors. We found that four components of nesting behavior were repeatable, and that accounting for age increased the repeatability estimate for maternal choice of canopy cover over nests. We detected canalization (diminished within-individual variance with age) of canopy cover choice in a reduced dataset despite no shift in repeatability. Additionally, random regression analysis revealed that females became more...对重复性（repeatability）的量化已助力行为生态学家与进化生态学家评估各类性状的遗传潜力。针对随生命周期发生变化的行为性状，需纳入年龄相关变异以避免偏倚目标微进化评估结果。此外，若要从机制层面理解行为的个体发育变异，需对生命周期内的个体间与个体内方差进行量化。本研究依托一项针对锦龟（Chrysemys picta）的30年长期调查，探究年龄如何影响筑巢行为重复性的变异情况。研究发现，筑巢行为的四个组成部分均具有重复性；且纳入年龄因素后，母体对巢上方冠层覆盖的选择行为的重复性评估值有所提升。尽管重复性未发生显著变化，但我们在缩减后的数据集内检测到冠层覆盖选择行为的稳态化（canalization）现象，即随年龄增长个体内方差降低。此外，随机回归分析（random regression analysis）显示，雌性个体的筑巢行为愈发……