Data from: Adaptive phenotypic plasticity in a clonal invader

Organisms featuring wide trait variability and occurring in a wide range of habitats, such as the ovoviviparous freshwater New Zealand snail Potamopyrgus antipodarum, are ideal models to study adaptation. Since the mid-19th century, P. antipodarum, characterized by extremely variable shell morphology, has successfully invaded aquatic areas on four continents. Because these obligately and wholy asexual invasive populations harbor low genetic diversity compared to mixed sexual/asexual populations in the native range, we hypothesized that 1) this phenotypic variation in the invasive range might be adaptive with respect to colonization of novel habitats, and 2) that at least some of the variation might be caused by phenotypic plasticity. We surveyed 425 snails from 21 localities across northwest Europe to attempt to disentangle genetic and environmental effects on shell morphology. We analysed brood size as proxy for fitness and shell geometric morphometrics, while controlling for genetic background. Our survey revealed 10 SNP genotypes nested into two mtDNA haplotypes and indicated that mainly lineage drove variation in shell shape but not size. Physicochemical parameters affected both shell shape and size and the interaction of these traits with brood size. In particular, stronger stream flow rates were associated with larger shells. Our measurements of brood size suggested that relatively larger slender snails with relatively large apertures were better adapted to strong flow than counterparts with broader shells and relatively small apertures. In conclusion, the apparent potential to modify shell morphology plays likely a key role in the invasive success of <i>P.antipodarum</i>; the two main components of shell morphology, namely shape and size, being differentially controlled, the former mainly genetically and the latter predominantely by phenotypic plasticity.

具有广泛性状变异且栖息于多样生境的生物，例如卵胎生淡水新西兰蜗牛（<i>Potamopyrgus antipodarum</i>），是研究适应性演化的理想模型体系。自19世纪中期以来，具有极丰富壳形变异的<i>P. antipodarum</i>已成功入侵全球四大洲的水生生境。由于这些专性且完全无性的入侵种群相较于原生分布区中混合有性/无性种群的遗传多样性更低，我们提出两项假说：其一，入侵区的表型变异或许可通过对新生境的定殖适应性加以解释；其二，至少部分表型变异可能由表型可塑性（phenotypic plasticity）所致。我们对欧洲西北部21个采样点的425只蜗牛开展了调查，以尝试解析遗传与环境因素对其壳形形态的影响。我们以窝卵数作为适合度（fitness）的代理指标，并结合几何形态测量学（geometric morphometrics）分析壳形，同时对遗传背景加以控制。本调查共检出10个单核苷酸多态性（Single Nucleotide Polymorphism, SNP）基因型，隶属于两个线粒体DNA（mitochondrial DNA, mtDNA）单倍型群，结果显示主要是谱系分化驱动了壳形的变异，但未对壳大小产生显著影响。理化参数同时影响壳形与壳大小，以及这两类性状与窝卵数之间的交互作用。具体而言，较高的溪流流速与更大的贝壳尺寸呈显著正相关。我们针对窝卵数的测量结果显示，相较于壳更宽、壳口相对较小的个体，体型相对修长且壳口较大的蜗牛更适应高流速环境。综上，调控壳形形态的潜在能力可能在<i>P. antipodarum</i>的入侵成功中发挥了关键作用；壳形形态的两大核心组分——壳形与壳大小——受到差异化调控：前者主要受遗传因素主导，而后者则主要由表型可塑性决定。