A replicated study on the response of spider assemblages to regional and local processes

Abstract

Understanding species richness variation among local communities is one of the central topics in ecology, but the complex interplay of regional processes, environmental filtering, and local processes hampers generalization on the importance of different processes. Here, we aim to unravel drivers of spider community assembly in temperate forests by analyzing two independent data sets covering gradients in elevation and forest succession. We test the following four hypotheses: (H1) spider assemblages within a region are limited by dispersal, (H2) local environment has a dominant influence on species composition and (H3) resources, and (H4) biotic interactions both affect species richness patterns. In a comprehensive approach, we studied species richness, abundance, taxonomic composition, and trait-phylogenetic dissimilarity of assemblages. The decrease in taxonomic similarity with increasing spatial distance was very weak, failing to support H1. Functional clustering of species in general and with canopy openness strongly supported H2. Moreover, this hypothesis was supported by a positive correlation between environmental and taxonomic similarity and by an increase in abundance with canopy openness. Resource determination of species richness (H3) could be confirmed only by the decrease of species richness with canopy cover. Finally, decreasing species richness with functional clustering indicating effects of biotic interactions (H4) could only be found in one analysis and only in one data set. In conclusion, our findings indicate that spider assemblages within a region are mainly determined by local environmental conditions, while resource availability, biotic interactions and dispersal play a minor role. Our approach shows that both the analysis of different aspects of species diversity and replication of community studies are necessary to identify the complex interplay of processes forming local assemblages.

Spatio‐temporal species aggregations do not rule out interspecific competition in tree hollow spider assemblages

“…Studies on the co-occurrence patterns in forest microhabitats are scarce (Azeria et al, 2012;Doerfler et al, 2020;Müller et al, 2022;Sánchez-Galván et al, 2018;Thorn et al, 2016).…”

“…Studies on the co‐occurrence patterns in forest microhabitats are scarce (Azeria et al, 2012; Doerfler et al, 2020; Müller et al, 2022; Sánchez‐Galván et al, 2018; Thorn et al, 2016). Co‐occurrence studies in exclusively predatory groups, such as spiders, are even scarcer (Birkhofer et al, 2010; Oliveira‐Junior et al, 2021).…”

“…It allows the identification of which species are found together more, less or as frequently as would be expected by chance and to focus on the factors responsible for such associations (Ulrich & Gotelli, 2007). In this way, non‐random aggregation patterns are related to similar ecological requirements (Müller et al, 2022; Peres‐Neto, 2004; Veech, 2006), mutualistic relationships (Holt, 1984; Sánchez‐Galván et al, 2018) or predator–prey associations (Hughes & Grabowski, 2006). In contrast, non‐random segregation patterns are attributed to competition phenomena (Camarota et al, 2016; Gotelli & Graves, 1996) or habitat filtering (Azeria et al, 2012; Oliveira‐Junior et al, 2021).…”

Morphological overdispersion supports the role of competition in the community assembly of dragonflies: drivers and spatio-seasonal variation

“…Functional community assembly has a long history in plant ecology, but it has only recently been adopted in animal ecology, where predominance of environmental filtering processes is generally identified. Examples of support for environmental filtering processes include studies on birds (Ricklefs 2012;Montaño-Centellas et al 2021), mammals (Belmaker & Jetz 2013), anurans (Schalk et al 2015), fish (Fitzgerald et al 2017) or arthropods (Van der Plas et al 2012;Greenop et al 2021;Muller et al 2022) among others. Conversely, support for the role of competition is uncommon.…”

Trait overdispersion in dragonflies reveals the role and drivers of competition in community assembly across space and season

“…Research on functional community assembly has a long history in plant ecology but it has only recently been adopted in animal ecology, where predominance of environmental filtering processes is generally identified. Examples of this include studies on birds (Montaño‐Centellas et al 2021), mammals (Belmaker and Jetz 2013), anurans (Schalk et al 2015), fish (Fitzgerald et al 2017), or arthropods (Van der Plas et al 2012, Müller et al 2022), among others. Conversely, support for the role of competition is uncommon.…”