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Rain, predators and vegetation lushness may structure web‐building spider communities along precipitation gradients
Author(s) -
Robertson Mark,
Avilés Leticia
Publication year - 2019
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1111/een.12699
Subject(s) - predation , vegetation (pathology) , ecology , precipitation , predator , abiotic component , abundance (ecology) , biology , canopy , spider , environmental science , geography , medicine , pathology , meteorology
1. Web building spider communities represent a vehicle for addressing how abiotic and biotic factors interact to structure natural communities. 2. The present study investigates how intense rainfall and potential predation by ants affect the proportion of three‐dimensional (3D) versus two‐dimensional (2D) spider webs along precipitation gradients. 3. Besides capturing prey, 3D webs may provide protection against predators, but they require a much greater material investment to be built than 2D webs. If costs take precedence over predator protection benefits, the proportion of 3D webs would decrease as precipitation increases (the ‘rain intensity’ hypothesis). Alternatively, if predator protection benefits take precedence, and the abundance of ants and other predators increases with precipitation, the proportion of 3D webs would increase with precipitation (the ‘predation risk’ hypothesis). 4. Seven sites were selected along a rain gradient of relatively uniform elevation and latitude in western Ecuador. Rain intensity, ant abundance and vegetation lushness (leaf area, canopy cover, tree diameter) were all observed to increase along the gradient, as did vegetation cover immediately above each web. 5. Relative to 2D webs, 3D webs increased in frequency with annual rainfall, consistent with the predation risk hypothesis but counter to the rain intensity hypothesis. 6. In areas of greater precipitation, however, lusher vegetation provided greater immediate vegetation cover to webs. Microhabitat factors may thus mitigate the destructive power of intense rainfall, thus allowing the predator protection benefits of 3D webs to be realised despite the occurrence of strong rains.