Energetic constraints on body-size niches in a resource-limited marine environment

Body size of life on Earth spans many orders of magnitude, and with it scales the energetic requirements of organisms. Thus, changes in environmental energy should impact community body-size distributions in predictable ways by reshaping ecological and niche dynamics. We examine how carbon, oxygen, and temperature, three energetic drivers, impact community size-based assembly in deep-sea bivalves. We demonstrate that body-size distributions are influenced by multiple energetic constraints. Relaxation in these constraints leads to an expansion of body-size niche space through the addition of novel large size classes, increasing the standard deviation and mean of the body-size distribution. With continued Anthropogenic increases in temperature and reductions in carbon availability and oxygen in most ocean basins, our results point to possible radical shifts in invertebrate body size with the potential to impact ecosystem function.

地球生命的体型跨度可达多个数量级，生物体的能量需求亦随体型呈尺度缩放关系。因此，环境能量的变化可通过重塑生态与生态位动态，以可预测的方式影响群落体型分布。本研究探讨了碳、氧与温度这三大能量驱动因子，如何作用于深海双壳类的基于体型的群落组装过程。研究结果表明，群落体型分布受到多重能量约束的调控：当这些约束得以缓解时，会通过新增全新的大型体型类群拓展体型生态位空间，进而增大体型分布的标准差与均值。随着全球绝大多数海盆持续出现人为驱动的升温、碳可用性降低与氧含量下降，本研究结果预示着无脊椎动物体型可能发生剧烈变化，并有可能对生态系统功能产生影响。