Large-scale ocean connectivity and planktonic body size

Global patterns of planktonic diversity are mainly determined by the dispersal of propagules with ocean currents. However, the role that abundance and body size plays in determining spatial patterns of diversity remains unclear. Here, we analyze spatial community structure - beta-diversity - for several planktonic and nektonic organisms spanning from prokaryotes to small mesopelagic fishes collected during the Malaspina 2010 Expedition. beta-diversity were compared to surface ocean transit times derived from a global circulation model, revealing a significant negative relationship that is stronger than environmental differences. Estimated dispersal scales for different groups show a negative correlation with body-size, where less abundant large-bodied communities have significantly shorter dispersal scales and larger spatial species-turnover rates than more abundant small-bodied plankton. Our results confirm that the dispersal scale of planktonic and micro-nektonic organisms is determined by local abundance, which scales with body size, ultimately setting global spatial patterns of diversity.

浮游生物多样性的全球格局主要由繁殖体随洋流的扩散过程所主导。然而，丰度与体型在调控多样性空间格局中所发挥的具体作用仍有待阐明。本研究针对2010年马尔帕斯皮纳探险（Malaspina 2010 Expedition）期间采集的、涵盖原核生物至小型中层深海鱼类的多种浮游与自游生物类群，分析其空间群落结构——β多样性（beta-diversity）。将β多样性与源自全球环流模型的海洋表层水体传输时间进行对比分析后发现，二者间存在显著负相关关系，且该关联的强度高于环境差异带来的影响。针对不同类群估算得到的扩散尺度与体型呈显著负相关：相较于丰度更高的小型浮游生物，丰度较低的大型生物群落拥有显著更短的扩散尺度与更高的空间物种更替率。本研究结果证实，浮游及微自游生物的扩散尺度由局地丰度决定，而局地丰度又随体型呈现尺度缩放规律，最终塑造了全球生物多样性的空间格局。