Joint Effect of Habitat Identity and Spatial Distance on Spiders’ Community Similarity in a Fragmented Transition Zone

Abstract

Understanding the main processes that affect community similarity have been the focus of much ecological research. However, the relative effects of environmental and spatial aspects in structuring ecological communities is still unresolved and is probably scale-dependent. Here, we examine the effect of habitat identity and spatial distance on fine-grained community similarity within a biogeographic transition zone. We compared four hypotheses: i) habitat identity alone, ii) spatial proximity alone, iii) non-interactive effects of both habitat identity and spatial proximity, and iv) interactive effect of habitat identity and spatial proximity. We explored these hypotheses for spiders in three fragmented landscapes located along the sharp climatic gradient of Southern Judea Lowlands (SJL), Israel. We sampled 14,854 spiders (from 199 species or morphospecies) in 644 samples, taken in 35 patches and stratified to nine different habitats. We calculated the Bray-Curtis similarity between all samples-pairs. We divided the pairwise values to four functional distance categories (same patch, different patches from the same landscape, adjacent landscapes and distant landscapes) and two habitat categories (same or different habitats) and compared them using non-parametric MANOVA. A significant interaction between habitat identity and spatial distance was found, such that the difference in mean similarity between same-habitat pairs and different-habitat pairs decreases with spatial distance. Additionally, community similarity decayed with spatial distance. Furthermore, at all distances, same-habitat pairs had higher similarity than different-habitats pairs. Our results support the fourth hypothesis of interactive effect of habitat identity and spatial proximity. We suggest that the environmental complexity of habitats or increased habitat specificity of species near the edge of their distribution range may explain this pattern. Thus, in transitions zones care should be taken when using habitats as surrogate of community composition in conservation planning since similar habitats in different locations are more likely to support different communities.

Habitat filtering and inferred dispersal ability condition across‐scale species turnover and rarity in Macaronesian island spider assemblages

“…Spiders are one of the most ubiquitous and diverse taxa in terrestrial ecosystems (Coddington & Levi, 1991). These arthropods are useful for understanding how dispersal and habitat interact (Florencio et al, 2016; Gavish & Ziv, 2016; Malumbres‐Olarte et al, 2014), and in the field of insular biogeography, they are providing evidence of how isolation, mobility and microhabitat size affect the functionality of species and assemblages (Méndez‐Castro et al, 2020) as well as colonisation and vicariance processes across archipelagos (Čandek et al, 2019; Gillespie, 2002; Rominger et al, 2015). Furthermore, spiders can be used to understand the effects of dispersal, between‐habitat differences and disturbance on the SADs of assemblages, providing useful information for conservation management (Boieiro et al, 2018; Borges et al, 2008; Cattin et al, 2003; Kaltsas et al, 2019; Kondratyeva et al, 2019; Leroy et al, 2014; Morel et al, 2019).…”

“…Spiders are one of the most ubiquitous and diverse taxa in terrestrial ecosystems (Coddington & Levi, 1991). These arthropods are useful for understanding how dispersal and habitat interact (Florencio et al, 2016;Gavish & Ziv, 2016;Malumbres-Olarte et al, 2014), and in the field of insular biogeography, they are providing evidence of how isolation, mobility and microhabitat size affect the functionality of species and assemblages (Méndez-Castro et al, 2020) as well as colonisation and vicariance processes across archipelagos (Čandek et al, 2019;Gillespie, 2002;Rominger et al, 2015).…”

Diversity metrics of spider communities associated with an understorey plant in tropical rain forest fragments

“…Spiders display a wide range of functional traits, including the following: dispersal abilities, foraging strategies and other behavioural patterns reflecting their essential relationship with the vegetation and habitat structure. Because of their ubiquity in different terrestrial ecosystems and habitat types, the Araneae has been widely used in studies that try to disentangle the different dimensions of biodiversity in perturbed ecosystems (Amaral-Nogueira & Pinto-da-Rocha 2016, Gavish & Ziv 2016, Lowe et al 2017, Podgaiski et al 2013.…”

“…Furthermore, old-growth forests have shown greater spider richness than open, disturbed areas and at early successional stages of the vegetation (Floren & Deeleman-Reinhold 2005). Recently, some conservation priority areas in Brazil have been proposed based on spiders' biodiversity dimensions (Gonçalves-Souza et al 2015).…”

Partitioning species and environmental diversity in fragmented landscapes: do the alpha, beta and gamma components match?

“…The list of 9 predefined habitats contained four structurally simple ones (exposed soil, annual plants < 15 cm tall, annual plants ≥ 15 cm tall and rosette plants) and five structurally complex habitats (two of these patch types were defined by the presence of a common perennial; either Sarcopoterium spinosum, or Hyparrhenia hirta, and the others by the main vegetation structure, bushes ≥ 35 cm tall, shrubs < 35 cm tall and thistles). The simple and complex habitats differ considerably in conditions and in spiders' community structure (Gavish and Ziv 2016).…”