Environmental heterogeneity predicts species richness of freshwater mollusks in sub-Saharan Africa
Environmental heterogeneity predicts species richness of freshwater mollusks in sub-Saharan Africa
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DOI：
10.1007/s00531-014-1109-3
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发表时间：
2016-09-01
影响因子：
2.3
通讯作者：
Albrecht, C.
中科院分区：
文献类型：
--
作者：
Hauffe, T.;Schultheiss, R.;Albrecht, C.
物种多样性及其在大陆尺度上的结构受到随机、生态和进化驱动力的影响，但关于决定因素的假设主要针对陆地和海洋生物进行了研究。非洲淡水软体动物的现存多样性一般很好地评估，以促进保护战略，因为几个分类群作为热带寄生虫的中间宿主的医学重要性。然而，这一历史知识的积累并没有导致对淡水软体动物空间分布的大量宏观生态学研究。在这里，我们使用大陆分布的数据和最近开发的随机和凝聚力分配的物种分布范围的方法来测试的相对重要性，在塑造物种丰富度的双壳类和腹足类的各种因素。我们发现，中域效应，也就是说，一个驼峰形的丰富度梯度在地理上有界的系统，尽管没有环境梯度，在确定物种丰富度在撒哈拉以南非洲的淡水软体动物中起着次要的作用。东非裂谷系统的西部分支被包括在丰富度模型中作为扩散屏障，但这些模拟结果并不适合观察到的多样性模式显着优于模型，这种影响不包括在内，这表明，裂谷在产生多样性模式中发挥了更复杂的作用。现今的降水和温度比Eemian气候条件更能解释丰富度模式。因此，在过去的初级生产力的水和能源的可用性不会影响目前的物种丰富度模式，和观察到的多样性模式似乎与当代气候平衡。地表沃茨的可利用性是双壳类和腹足类丰富度的最佳预测因子。我们的数据表明，栖息地的多样性导致所观察到的种-面积关系，因此，环境异质性是淡水软体动物丰富的大陆尺度上的主要驱动力。
Species diversity and how it is structured on a continental scale is influenced by stochastic, ecological, and evolutionary driving forces, but hypotheses on determining factors have been mainly examined for terrestrial and marine organisms. The extant diversity of African freshwater mollusks is in general well assessed to facilitate conservation strategies and because of the medical importance of several taxa as intermediate hosts for tropical parasites. This historical accumulation of knowledge has, however, not resulted in substantial macroecological studies on the spatial distribution of freshwater mollusks. Here, we use continental distribution data and a recently developed method of random and cohesive allocation of species distribution ranges to test the relative importance of various factors in shaping species richness of Bivalvia and Gastropoda. We show that the mid-domain effect, that is, a hump-shaped richness gradient in a geographically bounded system despite the absence of environmental gradients, plays a minor role in determining species richness of freshwater mollusks in sub-Saharan Africa. The western branch of the East African Rift System was included as dispersal barrier in richness models, but these simulation results did not fit observed diversity patterns significantly better than models where this effect was not included, which suggests that the rift has played a more complex role in generating diversity patterns. Present-day precipitation and temperature explain richness patterns better than Eemian climatic condition. Therefore, the availability of water and energy for primary productivity during the past does not influence current species richness patterns much, and observed diversity patterns appear to be in equilibrium with contemporary climate. The availability of surface waters was the best predictor of bivalve and gastropod richness. Our data indicate that habitat diversity causes the observed species-area relationship, and hence, that environmental heterogeneity is a principal driver of freshwater mollusk richness on a continental scale.