An experimental study of spiders in a shrub-steppe ecosystem: the effects of prey availability and shrub architecture

Abstract

Habitat structure is of great importance for the distribution and abundance of various organisms. Spiders are especially sensitive to structural features of their environment. Although spiders are influenced by habitat structure, it remains unclear whether spiders respond to architecture, to differences in prey availability associated with different architectures, or both. Here, we investigated the effects of shrub architecture and prey availability and their interactions on a spider community in a shrub-steppe environment in northern Utah, USA. Big sagebrush shrubs, matched by size, were randomly assigned to six experimental treatments: two levels of prey attractant (shrubs were either baited or not baited) and three levels of foliage density (low, natural/control, or high). We found that spider abundance and species richness were affected by both prey availability and shrub architecture, while variation in spider species diversity (Shannon-Wiener index) was governed by changes in shrub architecture. Spider species and family compositions were also associated with changes in shrub architecture, although guild composition was not. We discuss the implications and limitations of these findings and present suggestions for future research.

Arboreal spider assemblages associated with four tree species in the Grassland Biome of central South Africa (Arachnida: Araneae)

“…Balfour & Rypstra, 1998;Halaj et al, 1998;Borges & Brown, 2001;De Souza & Martins, 2005;Hore & Uniyal, 2010;Korenko et al, 2011;Spears & MacMahon, 2012). Other factors contributing to the occurrence of species on particular plants include specific physical characteristics of the foliage (Vasconcellos-Neto et al, 2007), vegetation orientation (Ysnel & Canard, 2000) and prey abundance (Halaj et al, 1998;Romero & Vasconcellos-Neto, 2004;Spears & MacMahon, 2012).…”

Impact of Habitat Complexity on Body Size of Two Spider Species, Alopecosa cuneata and A. pulverulenta (Araneae, Lycosidae), in River Valley Grasslands

“…Among the factors affecting spider assemblagestemperature, humidity, and availability of prey [39][40][41] Table 2. Results of GLMM analysis assessing the effect of habitat complexity, habitat type (mesic meadow, sandy grassland, xerothermic grassland), sex, and place on the mean body size of Alopecosa pulverulenta (N = 70).…”

“…For example, Halaj et al (2000) revealed that the abundance of Psocoptera and Collembola, which are typical spiders' prey, was greater in a more complex habitat [27]. Spears and MacMahon (2012) also found more prey items in shrubs with high foliage density compared to low foliage density [39]. Diehl et al (2013) showed that the order richness of spiders' prey increased with plant diversity and vegetation coverage [23].…”

Farming system shapes traits and composition of spider assemblages in Mediterranean cherry orchards

“…To offset the negative impacts associated with the decline of biodiversity and its underlying ecosystem services, alternative farming approaches such as organic agriculture are being promoted (Hole et al, 2005;Rahmann, 2011;Froidevaux, Louboutin Cady, 1999). At a local scale, the occurrence of spiders can be determined, among other factors, by habitat structural features (e.g., vegetation structure, architectural complexity and heterogeneity), microclimate conditions, prey availability, or the occurrence of habitat disturbance events (Halaj, Ross & Moldenke, 1998;Heikkinen & MacMahon, 2004;Horváth et al, 2005;Entling et al, 2010;Spears & MacMahon, 2012;Podgaiski et al, 2013;Battirola et al, 2016;Gómez, Lohmiller & Joern, 2016). Habitat characteristics can drive spider assemblages in terms of taxonomy and life-history traits (Cardoso et al, 2011;Dennis et al, 2015), but may also determine morphological variations, all these traits affecting the structure and dynamics of food webs (De Souza & Martins, 2004;Woodward et al, 2005;Entling et al, 2010;Podgaiski et al, 2013;Rosas-Ramos et al, 2018;Michalko, Pekár & Entling, 2019).…”

“…Morphological traits such as body size are determinant for spider adaptation and function in the environment and correlate with processes such as resource use, starvation, or desiccation resistance (Podgaiski et al, 2013). Since varying foraging strategies can result in spiders to be limited by different factors (Spears & MacMahon, 2012;Rosas-Ramos et al, 2018), we secondly asked how farming systems and the hillside aspect determine spider guild distribution and the individual body size within them.…”