Origination and Immigration Drive Latitudinal Gradients in Marine Functional Diversity

Global patterns in the functional attributes of organisms are critical to understanding biodiversity trends and predicting biotic responses to environmental change. In the first global marine analysis, we find a strong decrease in functional richness, but a strong increase in functional evenness, with increasing latitude using intertidal-to-outer-shelf bivalves as a model system (N = 5571 species). These patterns appear to be driven by the interplay between variation in origination rates among functional groups, and latitudinal patterns in origination and range expansion, as documented by the rich fossil record of the group. The data suggest that (i) accumulation of taxa in spatial bins and functional categories has not impeded continued diversification in the tropics, and (ii) extinctions will influence ecosystem function differentially across latitudes.

生物功能属性的全球格局，对于理解生物多样性变化趋势、预测生物群落对环境变化的响应至关重要。在首次全球海洋分析中，我们以潮间带至外陆架双壳类为模式系统（N=5571个物种），发现随着纬度升高，功能丰富度显著降低，而功能均匀度则显著提升。这些格局的形成似乎源于功能群间起源速率的差异，与起源和分布扩张的纬度格局之间的相互作用，这一机制已得到该类群丰富化石记录的佐证。本研究数据表明：其一，空间单元与功能类别中的分类群累积并未阻碍热带地区的持续物种多样化；其二，物种灭绝对生态系统功能的影响将随纬度呈现显著差异。