Data from: Postnatal dynamics of developmental stability and canalization of lizard head shape under different environmental conditions

Developmental stability (DS) and canalization are key determinants of phenotypic variation. To provide a better understanding of how postnatal growth is involved in determining the effects of DS and canalization on phenotypic variation, we studied within- and among-individual variation in head shape in ontogenetic series of lizards inhabiting urban and rural environments. Urban lizards exhibited increased fluctuating asymmetry during the early postnatal stages, but asymmetry levels decreased during growth. By contrast, asymmetry remained constant across the investigated size range in the rural population. In addition, urban juveniles were more variable for symmetric shape and deviated more from the group shape-size allometric trajectory, but both indices declined across ontogeny. Congruent patterns of within- and among-individual variation suggest that both DS and canalization may rely on similar underlying mechanisms. Further, the ontogenetic reduction of variation in the urban population suggests that compensatory growth may aid in buffering phenotypic variation and correcting deviances from the established developmental path. Alternatively, passive mechanisms and population dynamics may also explain the decrease of phenodeviants in urban populations. Significant correlations between symmetric and asymmetric shape, as well as similar integration patterns between the two populations, suggest that similar developmental mechanisms regulate head shape in both environments. Overall, these results highlight the relevance of both pre- and post-natal dynamics in determining levels of phenotypic variation, enhancing our understanding of how organisms respond to perturbations to DS and canalization under stressful conditions.发育稳定性（Developmental stability, DS）与渠化（canalization）是表型变异（phenotypic variation）的关键决定因素。为更深入理解产后生长如何参与调控发育稳定性与渠化对表型变异的影响，本研究针对栖息于城市与乡村生境中的蜥蜴类群，分析了其发育时序样本中头部形态的个体内与个体间变异。栖息于城市环境的蜥蜴在产后早期阶段表现出更高的波动不对称（fluctuating asymmetry）水平，但随着生长发育，其不对称程度逐渐降低；与之形成鲜明对比的是，乡村种群的不对称水平在研究所涉及的体型范围内始终保持稳定。此外，城市种群的幼体在对称形态上的变异程度更高，且更偏离群体的形态-体型异速生长轨迹，但这两项指标均随个体发育逐渐降低。个体内与个体间变异的一致模式表明，发育稳定性与渠化可能依赖于相似的潜在调控机制。进一步而言，城市种群中随发育进程出现的变异降低现象表明，补偿生长或许有助于缓冲表型变异，并修正偏离既定发育路径的偏差。此外，被动调控机制与种群动态或许也能解释城市种群中表型偏差个体（phenodeviants）数量的减少。对称形态与不对称形态间存在显著相关性，且两个种群的形态整合模式相似，这表明两种生境下的头部形态均受相似的发育机制调控。综上，本研究结果凸显了产前与产后动态在决定表型变异水平中的重要性，加深了我们对生物体在胁迫条件下如何响应发育稳定性与渠化扰动的理解。