Seymour Mathew, Räsänen Katja, Kristjánsson Bjarni K
Department of Aquaculture and Fish Biology Hólar University Skagafjörður Iceland.
Department of Aquatic Ecology EAWAG and Institute of Integrative Biology ETH-Zurich Dübendorf Switzerland.
Ecol Evol. 2019 Jun 27;9(14):8133-8145. doi: 10.1002/ece3.5381. eCollection 2019 Jul.
Divergence in phenotypic traits is facilitated by a combination of natural selection, phenotypic plasticity, gene flow, and genetic drift, whereby the role of drift is expected to be particularly important in small and isolated populations. Separating the components of phenotypic divergence is notoriously difficult, particularly for multivariate phenotypes. Here, we assessed phenotypic divergence of threespine stickleback () across 19 semi-interconnected ponds within a small geographic region (~7.5 km) using comparisons of multivariate phenotypic divergence (PST), neutral genetic (FST), and environmental (EST) variation. We found phenotypic divergence across the ponds in a suite of functionally relevant phenotypic traits, including feeding, defense, and swimming traits, and body shape (geometric morphometric). Comparisons of PSTs with FSTs suggest that phenotypic divergence is predominantly driven by neutral processes or stabilizing selection, whereas phenotypic divergence in defensive traits is in accordance with divergent selection. Comparisons of population pairwise PSTs with ESTs suggest that phenotypic divergence in swimming traits is correlated with prey availability, whereas there were no clear associations between phenotypic divergence and environmental difference in the other phenotypic groups. Overall, our results suggest that phenotypic divergence of these small populations at small geographic scales is largely driven by neutral processes (gene flow, drift), although environmental determinants (natural selection or phenotypic plasticity) may play a role.
表型性状的分化是由自然选择、表型可塑性、基因流和遗传漂变共同作用促成的，其中，遗传漂变在小种群和孤立种群中的作用预计尤为重要。区分表型分化的各个组成部分非常困难，尤其是对于多变量表型而言。在此，我们通过比较多变量表型分化（PST）、中性遗传（FST）和环境（EST）变异，评估了小地理区域（约7.5千米）内19个半相互连通池塘中三刺鱼（）的表型分化。我们发现，在一系列功能相关的表型性状中，包括摄食、防御和游泳性状以及体型（几何形态测量），各池塘间存在表型分化。PST与FST的比较表明，表型分化主要由中性过程或稳定选择驱动，而防御性状的表型分化符合趋异选择。种群成对PST与EST的比较表明，游泳性状的表型分化与猎物可利用性相关，而在其他表型组中，表型分化与环境差异之间没有明显关联。总体而言，我们的结果表明，在小地理尺度上，这些小种群的表型分化在很大程度上是由中性过程（基因流、遗传漂变）驱动的，尽管环境决定因素（自然选择或表型可塑性）可能也发挥了作用。
