The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans

AbstractWhile considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30º of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions, and traits can help us predict how communities may respond to environmental change., MethodsSee main manuscript for details.摘要 尽管已有大量证据表明物种互作强度存在生物地理格局，但此类格局对群落结构变异的影响仍不甚明确。本研究针对两大洋内跨越30个纬度的鳗草（Zostera marina）伴生甲壳动物的性状分散度指标开展模型选择分析，结果显示性状分散度随捕食压力增强与纬度降低显著升高。大洋类型与附生生物负荷为次要预测因子：太平洋海域的群落性状更趋过度分散，大西洋海域群落则更显聚集，且附生生物负荷升高与群落聚集程度增强呈正相关。通过探究物种互作与环境过滤如何调控不同生物地理区域的群落结构，本研究阐明了物种互作的纬度变异与历史偶然性共同塑造了上述群落响应模式。群落的性状分布对生态系统稳定性与功能具有重要意义，整合环境过滤、物种互作及性状的大尺度观测数据，将有助于我们预测群落对环境变化的响应方式。方法 详细方法参见主文稿。