Disentangling environmental, spatial, and historical effects on ostracod communities in shallow lakes

Abstract

Community structure is determined by a variety of ecological mechanisms, including environmental control, dispersal, and historical contingency. Recently, many studies have focused on the relative relevance of environment and dispersal in shaping metacommunities. Historical contingency (e.g., priority effects) rarely has been considered, although it could have a key role. In this context, the use of paleoecological methods could help assess the influence of past events on the present-day communities. In this survey, we compare living ostracod assemblages (i.e., biocoenoses) and subfossil assemblages (i.e., taphocoenoses) from 22 steppic shallow lakes and determine the relative contribution of environmental and spatial components on both assemblages. In addition, we estimate the role of putative priority effects of past assemblages on contemporary ones. Our results indicate a high concordance between both assemblages (Procrustes analysis; r = 0.877; P = 0.001). However, environment dominates over space in explaining the biocoenoses, whereas in taphocoenoses space dominates over environment. Furthermore, the contemporary metacommunity structure was related not only to pure environmental and spatial effects (suggesting species sorting and dispersal constraints) but also notably to pure historical effects, suggesting a significant major role of earlier habitat occupation in these ecosystems.