Assortative mating but no evidence of genetic divergence in a species characterized by a trophic polymorphism

Disruptive selection is a process that can result in multiple subgroups within a population, which is referred to as diversification. Foraging-related diversification has been described in many taxa, but many questions remain about the contribution of such diversification to reproductive isolation and potentially sympatric speciation. Here, we use stable isotope analysis of diet and morphological analysis of body shape to examine phenotypic divergence between littoral and pelagic foraging ecomorphs in a population of pumpkinseed sunfish (Lepomis gibbosus). We then examine reproductive isolation between ecomorphs by comparing the isotopic compositions of nesting males to eggs from their nests (a proxy for maternal diet) and use nine microsatellite loci to examine genetic divergence between ecomorphs. Our data support the presence of distinct foraging ecomorphs in this population and indicate that there is significant positive assortative mating based on diet. We did not find evidence of ...

歧化选择（Disruptive selection）是一类可促使种群内形成多个亚群的演化过程，该过程亦被称为多样化（diversification）。目前已有诸多分类群（taxa）被报道存在与觅食行为相关的多样化，但此类多样化对生殖隔离（reproductive isolation）以及潜在同域物种形成（sympatric speciation）的贡献仍存在诸多待解问题。本研究通过对食性开展稳定同位素分析（stable isotope analysis）以及对体型进行形态学分析，探究了南瓜籽太阳鱼（Lepomis gibbosus）种群中沿岸带与远洋带觅食生态型之间的表型分化（phenotypic divergence）。随后，我们通过比较筑巢雄鱼与其巢穴内卵粒的同位素组成（以此作为母体食性的替代指标），检测了不同生态型间的生殖隔离情况，并利用9个微卫星位点（microsatellite loci）分析了生态型间的遗传分化（genetic divergence）。本研究数据证实了该种群中存在分化显著的觅食生态型，且表明存在基于食性的显著正选型交配（positive assortative mating）。本研究未发现……的相关证据。