Cooperative foraging expands dietary niche but does not offset intra-group competition for resources in social spiders

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  • Marija Majer, Ben Gurion Univ Negev, Ben Gurion University, Blaustein Inst Desert Res, Mitrani Dept Desert Ecol
  • ,
  • Christina Holm
  • ,
  • Yael Lubin, Ben Gurion Univ Negev, Ben Gurion University, Blaustein Inst Desert Res, Mitrani Dept Desert Ecol
  • ,
  • Trine Bilde

Group living animals invariably risk resource competition. Cooperation in foraging, however, may benefit individuals in groups by facilitating an increase in dietary niche. To test this, we performed a comparative study of social and solitary spider species. Three independently derived social species of Stegodyphus (Eresidae) occupy semi-arid savannas and overlap with three solitary congeners. We estimated potential prey availability in the environment and prey acquisition by spiders in their capture webs. We calculated dietary niche width (prey size) and breadth (taxonomic range) to compare resource use for these six species, and investigated the relationships between group size and average individual capture web production, prey biomass intake rate and variance in biomass intake. Cooperative foraging increased dietary niche width and breadth by foraging opportunistically, including both larger prey and a wider taxonomic range of prey in the diet. Individual capture web production decreased with increasing group size, indicating energetic benefits of cooperation, and variance in individual intake rate was reduced. However, individual biomass intake also decreased with increasing group size. While cooperative foraging did not completely offset resource competition among group members, it may contribute to sustaining larger groups by reducing costs of web production, increasing the dietary niche and reducing the variance in prey capture.

Original languageEnglish
Article number11828
JournalScientific Reports
Volume8
Number of pages13
ISSN2045-2322
DOIs
Publication statusPublished - 7 Aug 2018

    Research areas

  • STEGODYPHUS-MIMOSARUM ARANEAE, PREY SIZE, INTRASPECIFIC COMPETITION, TERRESTRIAL ARTHROPODS, MATERNAL INVESTMENT, ANELOSIMUS-EXIMIUS, REPRODUCTIVE SKEW, INDIVIDUAL-LEVEL, COLONY SIZE, BODY-SIZE

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