Data from: Variation in body shape across species and populations in a radiation of Diaptomid copepods

AbstractInter and intra-population variation in morphological traits, such as body size and shape, provides important insights into the ecological importance of individual natural populations. The radiation of Diaptomid species (~400 species) has apparently produced little morphological differentiation other than those in secondary sexual characteristics, suggesting sexual, rather than ecological, selection has driven speciation. This evolutionary history suggests that species, and conspecific populations, would be ecologically redundant but recent work found contrasting ecosystem effects among both species and populations. This study provides the first quantification of shape variation among species, populations, and/or sexes (beyond taxonomic illustrations and body size measurements) to gain insight into the ecological differentiation of Diaptomids. Here we quantify the shape of five Diaptomid species (family Diaptomidae) from four populations each, using morphometric landmarks on the prosome, urosome, and antennae. We partition morphological variation among species, populations, and sexes, and test for phenotype-by-environment correlations to reveal possible functional consequences of shape variation. We found that intraspecific variation was 18-35% as large as interspecific variation across all measured traits. Interspecific variation in body size and relative antennae length, the two traits showing significant sexual dimorphism, were correlated with lake size and geographic location suggesting some niche differentiation between species. Observed relationships between intraspecific morphological variation and the environment suggest that divergent selection in contrasting lakes might contribute to shape differences among local populations, but confirming this requires further analyses. Our results show that although Diaptomid species differ in their reproductive traits, they also differ in other morphological traits that might indicate ecological differences among species and populations., Usage notesRaw data, processing code, processed data and analysis code + repeatability filesHausch 2013 PlosOne.zip

摘要
诸如体型与体形等形态性状的种群间及种群内变异，可为解析单个自然种群的生态重要性提供关键认知。镖水蚤类（Diaptomid）物种（约400种）的辐射演化过程中，除第二性征外几乎未出现明显的形态分化，这表明驱动其物种形成的是性选择而非生态选择。这一演化历程暗示，该类群的物种及其同种种群在生态功能上或存在冗余，但近期研究却发现不同物种与种群对生态系统的影响存在显著差异。
本研究首次针对物种、种群及雌雄个体间的体形变异开展量化分析（研究范畴超越了传统分类学绘图与体型测量），以解析镖水蚤类的生态分化特征。本研究针对隶属于镖水蚤科（Diaptomidae）的5个镖水蚤物种，每个物种选取4个种群，利用其前体部（prosome）、后体部（urosome）及触角上的形态测量地标点（morphometric landmarks），对体形进行量化分析。我们对物种、种群与雌雄个体间的形态变异进行分解，并开展表型-环境相关性分析，以揭示体形变异可能带来的功能效应。
研究结果显示，在所有被测性状中，种内变异的幅度为种间变异的18%~35%。存在显著性二态性（sexual dimorphism）的两个性状——体型与相对触角长度——的种间变异，与湖泊大小及地理位置存在相关性，这表明不同镖水蚤物种间存在一定的生态位分化（niche differentiation）。观测到的种内形态变异与环境间的关联表明，不同湖泊环境中的分化选择或许是导致当地种群间体形差异的原因，但该结论仍需进一步研究验证。本研究结果表明，尽管镖水蚤类物种在繁殖性状上存在差异，但它们在其他形态性状上同样存在分化，这或可表明不同物种与种群间存在生态差异。
使用说明：原始数据、处理代码、处理后数据、分析代码及可重复性文件，压缩包名称为Hausch 2013 PlosOne.zip