Data from: Evaluating shell variation across different populations of a freshwater snail

The freshwater snail Potamopyrgus antipodarum has become a model system for studying invasion ecology, host–parasite coevolution, the maintenance of sexual reproduction and ecotoxicology. One understudied aspect of this snail is the variation in morphology within and among populations, which could provide insights into ecological differences across its native range. In this study of 17 New Zealand lake populations of P. antipodarum we used linear measurements and geometric morphometrics to compare several aspects of shell size and shape. We found that, except for those from Lake Te Anau, most lake populations of P. antipodarum differ slightly in shape, but differ significantly in size and in the presence of spines, where larger and spinier snails are found in deeper regions. These striking distinctions in size and shell armature, but not in shape, suggest that the various components of form are under different selective regimes. Snails from Lake Te Anau are different in both shape and size, implying that this population is diverging from the rest of the species in multiple ways, making it an interesting study population for further research.淡水螺类新西兰扁卷螺（Potamopyrgus antipodarum）已成为入侵生态学、宿主-寄生虫共进化、有性繁殖维持以及生态毒理学研究的模式系统。该螺类尚未得到充分研究的一个方面，是种群内部及种群间的形态变异，这类变异或可揭示其原生分布范围内的生态差异。本研究针对17个新西兰湖泊中的P. antipodarum种群，采用线性测量法与几何形态测量学，对其壳体大小与形态的多项特征展开对比分析。结果显示，除来自蒂阿瑙湖的种群外，多数P. antipodarum湖泊种群的壳体形态仅存在细微差异，但在壳体大小以及棘突的有无上差异显著：体型更大、棘突更发达的个体多分布于较深水域。壳体大小与防护结构的显著差异（而非形态差异）表明，壳体形态的不同组分受到不同的选择压力调控。来自蒂阿瑙湖的螺类则在壳体形态与大小两方面均表现出显著差异，暗示该种群正从该物种的其他类群中发生多维度分化，因此具备作为后续研究对象的重要价值。