Data from: Metapopulation patterns of additive and nonadditive genetic variance in the sea bass (Dicentrarchus labrax)

Describing and explaining the geographic within-species variation in phenotypes (“phenogeography”) in the sea over a species distribution range is central to our understanding of a variety of eco-evolutionary topics. However, phenogeographic studies that have a large potential to investigate adaptive variation are overcome by phylogeographic studies, still mainly focusing on neutral markers. How genotypic and phenotypic data could covary over large geographic scales remains poorly understood in marine species. We crossed 75 noninbred sires (five origins) and 26 dams (two origins; each side of a hybrid zone) in a factorial diallel cross in order to investigate geographic variation for early survival and sex ratio in the metapopulation of the European sea bass (Dicentrarchus labrax), a highly prized marine fish species. Full-sib families (N = 1,950) were produced and reared in a common environment. Parentage assignment of 7,200 individuals was performed with seven microsatellite markers. Generalized linear models showed significant additive effects for both traits and pleiotropy between traits. A significant nonadditive genetic effect was detected. Different expression of traits and distinct relative performances were found for reciprocal crosses involving populations located on each side of the main hybrid zone located at the Almeria-Oran front, illustrating asymmetric reproductive isolation. The poor fitness performance observed for the Western Mediterranean population of sea bass is discussed as it represents the main source of seed hatchery production, but also because it potentially illustrates nonadaptive introgression and maladaptation.

在物种分布范围内，描述并阐释海洋物种的种内表型地理变异（phenogeography，表型生物地理学），是我们理解各类生态进化相关议题的核心所在。然而，虽具备探究适应性变异巨大潜力的表型生物地理学研究，其受关注程度却远不及仍以中性标记为主要研究对象的系统地理学（phylogeography）研究。在海洋物种中，基因型与表型数据如何在大地理尺度上发生共变异，目前仍鲜有研究得以阐明。本研究以极具经济价值的海洋鱼类欧洲海鲈（*Dicentrarchus labrax*）为对象，为探究其集合种群（metapopulation）的早期存活率与性比地理变异，采用因子式双列杂交（diallel cross）设计，将75个非近交父本（源自5个地理种群）与26个母本（源自2个地理种群，分别位于杂交带两侧）进行杂交。共构建全同胞家系1950个，并在统一可控环境下完成饲养培育。本研究借助7个微卫星标记（microsatellite markers），对7200个个体开展了亲权鉴定。广义线性模型（Generalized Linear Models）分析结果显示，两个性状均存在显著的加性遗传效应，且性状间存在多效性（pleiotropy）关联。同时还检测到了显著的非加性遗传效应。针对位于阿尔梅里亚-奥兰锋面的主要杂交带两侧种群所开展的互交实验显示，不同性状的表达模式与相对表现均存在显著差异，表明存在不对称的生殖隔离。本研究还针对西地中海海鲈种群较低的适合度表现展开了讨论：该种群目前是海鲈苗种孵化生产的主要来源，同时其较低的适合度也可能反映了非适应性渐渗（nonadaptive introgression）与适应不良（maladaptation）现象。