Data from: Does morphological variation buffer against extinction? A test using veneroid bivalves from the Plio-Pleistocene of Florida

Although morphological variation is known to influence the evolutionary fates of species, the relationship between morphological variation and survivorship in the face of extinction-inducing perturbations is poorly understood. Here, we investigate this relationship for veneroid bivalves in association with the Plio-Pleistocene extinction in Florida. Fourteen pairs of related species were selected for analysis, with each pair including one species that survived the Plio-Pleistocene extinction and another that became extinct during the interval. Morphological landmark data were acquired for more than 1500 museum specimens, representing 19 localities that encompass four well-known Plio-Pleistocene units in the study region. Procrustes superimposition was applied to each sample, and overall multivariate variation was calculated as the mean squared partial Procrustes distance between specimens and their mean form. Morphological variation was calculated at three geographic scales for each species, and differences in variation between survivors and victims were examined within each species pair. Results indicate that species surviving the Plio-Pleistocene extinction were significantly more variable morphologically than victims. Greater morphological variation may promote survivorship by directly enhancing species adaptations to changing conditions or by permitting the occupation of a larger geographic range. Alternatively, high morphological variation and survivorship may both be mediated by a third variable, such as large geographic range.尽管形态变异对物种演化命运的影响已为学界所熟知，但在遭遇诱发灭绝的扰动时，形态变异与物种存活之间的关联仍未得到充分阐释。本研究以佛罗里达州上新世-更新世（Plio-Pleistocene）灭绝事件中的帘蛤类双壳动物（veneroid bivalves）为研究对象，探究二者间的关联。研究共选取14组近缘物种开展分析，每组包含1种在上新世-更新世灭绝事件中存活的物种，以及1种在该时期内灭绝的物种。研究采集了覆盖研究区域内4个经典上新世-更新世地层单元的19个采样点的1500余件馆藏标本的形态学地标数据（morphological landmark data）。对每个样本实施普氏叠加（Procrustes superimposition）处理，并以标本与其平均形态间的平均平方偏普氏距离计算整体多变量形态变异度。我们针对每个物种在三个地理尺度下计算形态变异度，并在每组物种对中比较存活物种与灭绝物种的变异度差异。结果显示，在上新世-更新世灭绝事件中存活的物种，其形态变异度显著高于灭绝物种。更高的形态变异度可通过两种路径提升物种存活能力：一是直接增强物种对环境变化的适应能力，二是帮助物种占据更广的地理分布范围。此外，高形态变异度与物种存活也可能同时受第三类变量调控，例如广阔的地理分布范围。