Fuentealba Jara Carmen Gloria, Rivera Reinaldo, Franco Cristian, Figueroa Ricardo, Faúndez Victor
Instituto de Ciencias Naturales, Universidad de las Américas, Concepción, Chile.
Laboratorio de Ecología Evolutiva y Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas. Universidad de Concepción, Concepción, Chile.
PeerJ. 2019 Jul 5;7:e7097. doi: 10.7717/peerj.7097. eCollection 2019.
The freshwater mussels from Chile are characterized by a high percentage of endemism and a fragmented latitudinal diversity, which has been attributed to the features and geomorphological history sculpted by the hydrographic basins. In this work, a set of hypothesis under a macroecological approach is addressed, with the aim to explore environmental, topographic and hydrological factors that define the latitudinal distribution of this mussel group. In order to achieve this goal, Rapoport's rule, geometrics limits and co-ocurrence were evaluated. In addition, we analyze the source and sink hypotheses through the nested analysis. We observed a noticeable mid-domain effect (MDE), where a major richness than expected was randomly observed between 40 and 41°S. The results revealed that the distribution pattern was not concordant with Rapoport's rule ( = 0.123; = 0.128). Regarding to historical dynamic of the distribution, the results show a significant nestedness pattern, suggesting a source-sink dynamic, that is, poorer communities are a subset of richer communities in species. According to the co-occurrence analysis, an aggregate pattern existed, suggesting potential regulatory mechanisms. The specific richness pattern is explained by the variable seasonality of the temperature with a variance percentage explained of 35%. The full model indicated that variables which characterize the heterogeneity of habitat (i.e. range, Shannon), water availability (i.e., precipitation, density of water bodies) and topography (i.e., altitude area available) jointly explain 40% of the variability of the observed richness. This study shows that the geographical distribution of mollusc richness is mainly explained by mainly climatic and topographical environmental components, as well as by the source-sink dynamics.
智利的淡水贻贝具有高比例的特有性和破碎的纬度多样性，这归因于水文盆地塑造的特征和地貌历史。在这项工作中，我们采用宏观生态方法探讨了一系列假设，旨在探究定义该贻贝群纬度分布的环境、地形和水文因素。为实现这一目标，我们评估了拉波波特法则、几何极限和共现情况。此外，我们通过嵌套分析来分析源 - 汇假设。我们观察到明显的中间区域效应（MDE），即在南纬40度至41度之间随机观察到比预期更高的丰富度。结果表明，分布模式与拉波波特法则不一致（r = 0.123；p = 0.128）。关于分布的历史动态，结果显示出显著的嵌套模式，表明存在源 - 汇动态，即较贫乏的群落是物种较丰富群落的子集。根据共现分析，存在聚集模式，表明存在潜在的调节机制。特定丰富度模式由温度的可变季节性解释，解释方差百分比为35%。完整模型表明，表征栖息地异质性的变量（即范围、香农指数）、水的可利用性（即降水量、水体密度）和地形（即可用海拔面积）共同解释了观察到的丰富度变化的40%。这项研究表明，软体动物丰富度的地理分布主要由气候和地形环境成分以及源 - 汇动态来解释。
