Patch shape alters spider community structure: links between microhabitat choice and sensitivity to increased edge habitat

Abstract

Increased edge effects in fragmented habitats can affect the abundance of edge-dwelling organisms, but these impacts may depend on the biological attributes of species. Microhabitat choice, a species characteristic that reflects combinations of biological traits, may affect the ability of peripheral species to take advantage of increased edge habitat in the presence of edge effects. In this field study, we built artificial shrub modules designed to encourage web spiders to build webs on the periphery. While modules were identical in volume, they differed in shape (cubic and elongated), so that elongated modules had more edge habitat and were subject to enhanced edge effects. Given that the tangle-web spiders Theridion and Dictyna built webs on module edges and strongly differed in terms of concealment and substrate generalization, two habitat characteristics associated with lower vulnerability to habitat modification, we tested the hypothesis that Theridion, which built webs in more concealed locations and on a greater diversity of substrate configurations in the modules compared to Dictyna, would take better advantage of increased edge habitat. As predicted, Theridion was significantly more abundant on elongated modules whereas the abundance of Dictyna did not respond to shape, even though the change in module shape entailed a similar increase in favored substrate for both spider groups. Our results suggest that the microhabitat associations of organisms may be linked to their propensity to be sensitive to edges, and that a better understanding of these links can improve our ability to predict the effects of habitat modification on biodiversity.

The Influence of Solar Power Plants on Microclimatic Conditions and the Biotic Community in Chilean Desert Environments

“…For example, some spider species might consider solar panels as discrete habitat patches, and web spiders at habitat edges are expected to increase because of the facilitation to build webs in anthropic environments and to improve their fitness (Wise 2006). As a result from the increase in edge habitation, there were changes in species interactions which may be beneficial or detrimental to edge organisms depending on their intrinsic ecological traits (Cobbold & Supp 2012). The latter supports the idea that the structure of fixed-mounts determined the spatial assemblage pattern rather than abiotic conditions.…”

Riparian Vegetation Structure Influences Terrestrial Invertebrate Communities in an Agricultural Landscape

“…Spider and ground beetle communities respond structurally to environmental change, indicating that they can provide valuable information for ecological impact assessment [101]. Both Tetragnathidae and Lycosidae are regarded as adequate biological indicators of habitat modification due to their potential to provide early warnings of environmental change [115][116][117]. These predatory invertebrates (e.g., tetragnathid and lycosid spiders, as well as carabid and staphylinid beetles) may be important sentinels of change because of their importance in controlling crop pest populations [92,118].…”

Effects of landscape complexity and stand factors on arthropod communities in poplar forests

“…Collinge and Palmer (2002) showed that movement of grounddwelling beetles across patch boundaries may be affected by patch shape. Habitat patch shape seems to have a significant effect on the community structure of predators by modifying their microhabitat choice (Cobbold & Supp, 2012). In a word, patch shape may play an important role among defoliators and natural enemies (Olson & Andow, 2008).…”