Broad-scale rather than fine-scale environmental variation drives body size in a wandering predator (Araneae, Lycosidae)

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Nils Hein, Julien Pétillon, Roland Pape, Hannes Feilhauer, Kim A. Vanselow, Jörg Löffler
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2019
• Subjects: individual trait; random forest; wolf spider; norway; pardosa palustris; Environmental sciences; GE1-350; Ecology; QH540-549.5; Arctic; Norway; Antarctic and Alpine Research
• Online Access: https://doi.org/10.1080/15230430.2019.1640039; https://doaj.org/article/6f955cc6420a40c5bb34161861117c3c

Body size is one of the most important individual traits, determining various other life-history traits, including fitness. Both evolutionary and ecological factors shape the body size in arthropods, but the relative contribution of abiotic drivers acting at different spatial scales has been little investigated. We aimed to identify the importance of two broad-scale variables (study region and elevation) in shaping body size of the free-running and locally abundant wolf spider Pardosa palustris (Linnaeus 1758), in contrast to the fine-scaled variable topographic position. Therefore, we set up transects along environmental gradients in the arctic-alpine ecosystems of Norway, which we analyzed using a random forest approach to identify the relative importance of topographic position, elevation, and study region on body size of P. palustris. Our approach revealed that research region was the best explanatory variable, followed by elevation and topographic position. Differences in body size were most likely a consequence of the pronounced differences in season length and the ability of P. palustris to avoid local unfavorable environmental conditions due to its high mobility.