Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Sci Total Environ. 2019 Apr 1;659:451-462. doi: 10.1016/j.scitotenv.2018.12.373. Epub 2018 Dec 26.
Current understanding of different facets of beta diversity and their underlying determinants remains limited at broad scales in the freshwater realm. We examined the geographical patterns and spatial congruence of three beta diversity facets of freshwater molluscs across all of China, and evaluated the relative importance of environmental and spatial factors underlying the observed patterns. Taxonomic (β-TD), functional (β-FD) and phylogenetic (β-PD) beta diversity were calculated for 212 drainage basins belonging to 10 hydrographic regions using compiled occurrence data of 313 molluscan species. Geographical patterns of the three diversity facets were visualized on maps and pairwise spatial congruence among them was evaluated using regression on distance matrices. Variation partitioning and multivariate regression trees were used to assess the relative importance of different factors underlying beta diversity patterns. Beta diversity maps revealed that geographical patterns of β-TD and β-PD showed strong spatial clustering and were well matched with hydrographic regions' boundaries, while β-FD showed only moderate spatial aggregation. The three facets were only moderately congruent, with over 60% of the variation in one facet remaining unexplained by any other facet. Remarkably, all diversity facets were best explained by the spatial factors with considerable unique effects. Environmental filtering associated with energy gradients also made a large contribution, while habitat availability only explained minor fractions of the variation in beta diversity. At the national scale, β-TD and β-PD were more strongly related to spatial processes, whereas β-FD was more strongly associated with energy gradients. Our results suggested that, for freshwater organisms with low dispersal capacity, dispersal processes may override environmental filtering in driving geographical diversity patterns. However, different ecological drivers were important for each diversity facet. Importantly, rather weak spatial congruence among the different diversity facets stresses the need to incorporate functional and phylogenetic facets into the development of conservation planning.
目前，在淡水领域，人们对贝塔多样性的不同方面及其潜在决定因素的理解仍然有限，尤其是在广泛的尺度上。我们研究了中国所有地区淡水软体动物的三个贝塔多样性方面的地理格局和空间一致性，并评估了观察到的模式背后环境和空间因素的相对重要性。使用 313 种软体动物物种的综合出现数据，为属于 10 个水文区域的 212 个流域计算了分类（β-TD）、功能（β-FD）和系统发育（β-PD）贝塔多样性。在地图上可视化了三个多样性方面的地理格局，并通过距离矩阵回归评估了它们之间的两两空间一致性。方差分解和多元回归树用于评估贝塔多样性模式背后不同因素的相对重要性。贝塔多样性图表明，β-TD 和 β-PD 的地理格局显示出强烈的空间聚类，与水文区域的边界非常吻合，而 β-FD 仅显示出适度的空间聚集。这三个方面仅具有中等一致性，一个方面的变化有超过 60%无法用任何其他方面来解释。值得注意的是，所有的多样性方面都最好由空间因素来解释，这些因素具有相当大的独特效应。与能量梯度相关的环境过滤也做出了很大的贡献，而栖息地的可用性仅解释了贝塔多样性变化的一小部分。在国家尺度上，β-TD 和 β-PD 与空间过程的关系更为密切，而 β-FD 与能量梯度的关系更为密切。我们的结果表明，对于扩散能力较低的淡水生物，扩散过程可能会在驱动地理多样性模式方面超过环境过滤。然而，不同的生态驱动因素对每个多样性方面都很重要。重要的是，不同多样性方面之间的空间一致性较弱，这强调了在制定保护规划时需要将功能和系统发育方面纳入其中。
