Data from: The quantitative genetics of physiological and morphological traits in an invasive terrestrial snail: additive versus non-additive genetic variation

1. The distribution of additive versus non-additive genetic variation in natural populations represents a central topic of research in evolutionary/organismal biology. For evolutionary physiologists, functional or whole-animal performance traits (“physiological traits”) are frequently studied assuming they are heritable and variable in populations. 2. Physiological traits of evolutionary relevance are those functional capacities measured at the whole-organism level, with a potential impact on fitness. They can be classified as capacities (or performances) or costs, the former being directly correlated with fitness, and the latter being inversely correlated with fitness (usually assumed as constraints). 3. In spite of their obvious adaptive significance, the additive genetic variation of physiological traits, and its relative contribution to phenotypic variance (or narrow-sense heritability) in comparison to maternal, dominance or epistatic variance, is known only for a few groups such as insects and mammals. 4. In this study, we assessed the additive and maternal/non-additive genetic variation in a suite of physiological and morphological traits in populations of the land snail Cornu aspersum. 5.Except for dehydration rate (h2= 0.32 ± 0.15), egg mass (h2= 0.82 ± 0.30) and hatchling mass (h2= 1.01 ± 0.31) (population = fixed effect), we found very low additive genetic variation. Large non-additive/maternal effects were found in all traits. Cage effects did not change the results, indicating low contribution of common environmental variance to our results. No differences were found between the phenotypic or non-additive genetic variance/covariance matrices. 6. Even though we compared populations across 1300 km in a common garden setup, our results suggest an absence of physiological as well as morphological differentiation in these populations. 7. These results contrast with previous analyses in the original distributional range of this species, which found high additive genetic variation in morphological traits. These are intriguing results demanding further quantitative genetic studies in the original distributional range of this species as well as the history of colonization of this invasive species.

1. 自然种群中加性与非加性遗传变异的分布模式，是进化生物学/有机体生物学领域的核心研究议题之一。对于进化生理学家而言，功能层面或整体动物的性能性状（physiological traits）常被假定为在种群中具有可遗传性与表型变异，并以此为前提开展研究。
2. 具有进化意义的生理性状，是指在整体有机体水平上测得的、可能对适合度（fitness）产生影响的功能性能。这类性状可分为性能（或功能能力）与消耗成本两类：前者与适合度呈正相关，后者则与适合度呈负相关（通常被视为进化约束）。
3. 尽管生理性状具有明确的适应性意义，但目前仅在昆虫、哺乳动物等少数类群中，明确了其加性遗传变异水平，以及相较于母体方差、显性方差或上位性方差的相对贡献（即对表型方差的占比，或称狭义遗传力（narrow-sense heritability））。
4. 本研究针对陆生蜗牛Cornu aspersum种群的一系列生理与形态性状，评估了其加性遗传变异以及母体/非加性遗传变异水平。
5. 除脱水速率（h²=0.32±0.15）、卵重（h²=0.82±0.30）以及幼体孵化重（h²=1.01±0.31）（种群作为固定效应）外，其余性状均表现出极低的加性遗传变异。所有性状均检测到较强的非加性/母体效应。笼养环境效应未对结果产生显著影响，表明共同环境方差对本研究结果的贡献极低。此外，表型方差/协方差矩阵与非加性遗传方差/协方差矩阵之间未发现显著差异。
6. 尽管本研究通过同质园（common garden）实验设计，对跨度1300公里的多个种群进行了比较，但结果显示这些种群在生理与形态层面均未出现显著分化。
7. 本研究结果与该物种原生分布区内过往的定量遗传研究结论相悖——过往研究在形态性状中检测到了较高的加性遗传变异。该结果颇具研究价值，亟待在该物种的原生分布区内开展更多定量遗传（quantitative genetic）研究，并结合该入侵物种的定殖历史展开深入探讨。