A population genetic assessment of taxonomic species: the case of Lake Malawi cichlid fishes

Organisms sampled for population level research are typically assigned to species by morphological criteria. But if those criteria are limited to one sex or life stage, or the organisms come from a complex of closely related forms, the species assignments may misdirect analyses. The impact of such sampling can be assessed from the correspondence of genetic clusters, identified only from patterns of genetic variation, to the species identified using only phenotypic criteria. We undertook this protocol with the rock-dwelling mbuna cichlids of Lake Malawi, for which species within genera are usually identified by investigators using adult male coloration patterns. Given high local endemism of male color patterns, and considerable allele sharing among species, there persists considerable taxonomic uncertainty in these fishes. Over 700 individuals from a single transect were photographed, genotyped, and separately assigned: (1) to morphospecies using photographs; and (2) to genetic clusters ...

用于种群水平研究的采样生物，通常通过形态学标准完成物种划分。但若此类鉴定标准仅适用于单一性别或特定发育阶段，或是采样生物来自近缘类群复合体，则物种划分结果可能误导后续分析。此类采样带来的潜在影响，可通过仅基于遗传变异模式界定的遗传簇（genetic clusters）与仅通过表型标准（phenotypic criteria）鉴定的物种之间的对应关系进行评估。我们以马拉维湖岩栖慈鲷类（rock-dwelling mbuna cichlids）为研究对象开展了该实验方案：该类群的属内物种通常由研究者凭借成年雄性的体色模式完成鉴定。鉴于雄性体色模式具有高度的地方性特有分布特征，且不同物种间存在大量等位基因共享现象，该类群鱼类长期存在显著的分类学不确定性。本研究对单个样带采集的700余尾个体进行了拍照、基因分型，并分别完成归类：(1) 基于照片鉴定为形态种（morphospecies）；(2) 划分为遗传簇……