Climate change and body size shift in Mediterranean bivalve assemblages: unexpected role of biological invasions

Body size is a synthetic functional trait determining many key ecosystem properties. Reduction in average body size has been suggested as one of the universal responses to global warming in aquatic ecosystems. Climate change, however, coincides with human-enhanced dispersal of alien species and can facilitate their establishment. We address effects of species introductions on the size structure of recipient communities using data on Red Sea bivalves entering the Mediterranean Sea through the Suez Canal. We show that the invasion leads to increase in median body size of the Mediterranean assemblage. Alien species are significantly larger than native Mediterranean bivalves, even though they represent a random subset of the Red Sea species with respect to body size. The observed patterns result primarily from the differences in the taxonomic composition and body-size distributions of the source and recipient species pools. In contrast to the expectations based on the general temperature–si...

体型大小是一种合成功能性状（synthetic functional trait），决定着生态系统的诸多关键属性。平均体型减小被认为是水生生态系统对全球变暖的普遍响应之一。然而，气候变化与人类活动加剧的外来物种扩散相叠加，可能促进其定殖。我们利用红海双壳类通过苏伊士运河进入地中海的数据，探讨了物种引入对受体群落体型结构的影响。研究表明，入侵导致地中海群落的中位体型增大。外来物种的体型显著大于地中海本地双壳类，尽管就体型而言，它们是红海物种的随机子集。观察到的模式主要源于源物种库和受体物种库在分类组成及体型分布上的差异。与基于一般温度—体...