Data from: Integrating candidate gene and quantitative genetic approaches to understand variation in timing of breeding in wild tit populations

Two commonly used techniques for estimating the effect of genes on traits in wild populations are the candidate gene approach and quantitative genetic analyses. However, whether these two approaches measure the same underlying processes remains unresolved. Here we use these two methods to test if they are alternative or complementary approaches to understanding genetic variation in the timing of reproduction – a key trait involved in adaptation to climate change - in wild tit populations. Our analyses of the candidate gene Clock show weak correlates with timing variables in blue tits, but no association in great tits, confirming earlier results. Quantitative genetic analyses revealed very low levels of both direct (female) and indirect (male) additive genetic variation in timing traits for both species, in contrast to previous studies on these traits, and much lower than generally assumed. Hence, neither method suggests strong genetic effects on timing of breeding in birds and further work should seek to assess the generality of these conclusions. We discuss how differences in the genetic control of traits, species life-history and confounding environmental variables may determine how useful integrating these two techniques is to understand phenotypic variation in wild populations.

在野生种群中，用于评估基因对性状影响的两种常用技术分别为候选基因法（candidate gene approach）与数量遗传分析（quantitative genetic analyses）。然而，这两种方法是否针对相同的核心生物学过程进行量化，目前仍未有定论。本研究采用这两种方法，针对野生山雀种群的繁殖时序——一类与气候变化适应密切相关的关键性状——展开验证分析，以明确二者是互斥替代还是互为补充的研究路径，进而解析繁殖时序的遗传变异机制。针对时钟基因Clock（Clock）的分析结果显示，其与蓝山雀（blue tits）的繁殖时序变量仅存在微弱相关性，但在大山雀（great tits）中未发现任何关联，这一结果验证了此前的相关研究结论。数量遗传分析结果显示，两个物种的繁殖时序性状均存在极低水平的直接（雌性）与间接（雄性）加性遗传变异，这与此前针对该性状的研究结论相悖，且远低于学界普遍的假设水平。综上，两种方法均未发现鸟类繁殖时序存在显著的遗传效应，后续研究应致力于评估上述结论的普适性。本研究还探讨了性状遗传调控机制的差异、物种生活史特征以及混淆性环境变量将如何影响整合这两种技术以解析野生种群表型变异的应用价值。