Community structure of invertebrate fauna in Central Chilean Rivers

Abstract Aim River systems of Central Chile are short, steep and fast flowing. They are characterized by discharge regimes dominated by rainfall and snowmelt. Invertebrate fauna is highly endemic. This study aimed to describe the community structure of invertebrate in eight river systems in Central Chile (33-39°S) using species co-occurrence and niche sharing null models. Methods Invertebrate samples were collected from Central Chilean rivers (33-39°S), data were analyzed co-occurrence species and niche sharing null models for determine potential structuring patterns. Results The results revealed the presence of non-structured patterns in co-occurrence considering each site as well as all sites, that is most probably an effect of presence of many repeated species in the studied sites. Furthermore, we found the existence of niche overlap due to interspecific competition at each site and among all sites. The results obtained from these river systems corroborate observations from Chilean Patagonian Rivers. Conclusion This study contributes to understanding of biogeographical and ecological patterns of invertebrate communities in central Chilean Rivers and provide foundations for more complex ecological studies.摘要 研究目标：智利中部河系普遍短小、坡陡流急，其径流格局以降雨与融雪为主导。该区域无脊椎动物区系（invertebrate fauna）具有高度的特有性（endemism）。本研究旨在利用物种共现（species co-occurrence）与生态位共享（niche sharing）零模型（null models），对智利中部（南纬33°~39°）的八条河系的无脊椎动物群落结构进行解析。 研究方法：采集智利中部（南纬33°~39°）河流的无脊椎动物样本，采用物种共现（species co-occurrence）与生态位共享（niche sharing）零模型（null models）对数据开展分析，以探究潜在的群落构建格局（structuring patterns）。 研究结果：结果显示，无论是以单个样点还是全部样点作为分析单元，物种共现模式均未呈现结构化特征，这大概率源于研究样点中存在大量跨样点重复出现的物种。此外，在单个样点及全部样点尺度上，均检测到由种间竞争（interspecific competition）引发的生态位重叠（niche overlap）现象。本研究针对该类河系得到的结果，与智利巴塔哥尼亚河流的相关观测结果相一致。 研究结论：本研究有助于深化对智利中部河流无脊椎动物群落生物地理（biogeographical）与生态格局（ecological patterns）的认知，可为后续更复杂的生态学研究奠定理论基础。