Submission Type
Oral Presentation
Abstract
Web-building spiders are important predators in most terrestrial habitats. Web damage is common and presents potential fitness consequences for the spider. Falling woody debris is likely a major source of web damage for forest-dwelling spiders, especially Leucauge venusta, a widespread species that builds horizontal webs. We quantified damage area, general dimensions, and spatial orientation of L. venusta webs in two Kentucky forests. We also measured woody debris fall from the canopy. We experimentally damaged webs with falling debris in the lab to test the hypothesis that L. venusta change their web orientation following disturbance. The relative area of webs naturally damaged in the field increased with decreasing web angle (i.e., more horizontal). By contrast, the relative area of damage increased with increasing web angle (more vertical) in the lab. These results indicate that webs with greater vertical orientation experience more damage than horizontal webs when struck by falling debris, but on average are less likely to be struck. Collectively, the results of this study suggest that L. venusta orientate their webs to balance potential tradeoffs between prey capture and risk of damage. Measuring such tradeoffs improves our understanding of the selective pressures faced by forest-dwelling arthropods, and how those pressures shape local species distributions.
Included in
Spider web morphology is associated with damage by falling woody debris
Web-building spiders are important predators in most terrestrial habitats. Web damage is common and presents potential fitness consequences for the spider. Falling woody debris is likely a major source of web damage for forest-dwelling spiders, especially Leucauge venusta, a widespread species that builds horizontal webs. We quantified damage area, general dimensions, and spatial orientation of L. venusta webs in two Kentucky forests. We also measured woody debris fall from the canopy. We experimentally damaged webs with falling debris in the lab to test the hypothesis that L. venusta change their web orientation following disturbance. The relative area of webs naturally damaged in the field increased with decreasing web angle (i.e., more horizontal). By contrast, the relative area of damage increased with increasing web angle (more vertical) in the lab. These results indicate that webs with greater vertical orientation experience more damage than horizontal webs when struck by falling debris, but on average are less likely to be struck. Collectively, the results of this study suggest that L. venusta orientate their webs to balance potential tradeoffs between prey capture and risk of damage. Measuring such tradeoffs improves our understanding of the selective pressures faced by forest-dwelling arthropods, and how those pressures shape local species distributions.
Comments
Abigail K. Nienaber1 and Stephen P. Yanoviak1,2
1 Department of Biology, University of Louisville, Louisville, KY 40292, 2 Smithsonian Tropical Research Institute, Balboa, Panama