Foraging mode affects the evolution of egg size in generalist predators embedded in complex food webs

O. Verdeny-Vilalta, C. W. Fox, D. H. Wise, J. Moya-Laraño

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Ecological networks incorporate myriad biotic interactions that determine the selection pressures experienced by the embedded populations. We argue that within food webs, the negative scaling of abundance with body mass and foraging theory predict that the selective advantages of larger egg size should be smaller for sit-and-wait than active-hunting generalist predators, leading to the evolution of a difference in egg size between them. Because body mass usually scales negatively with predator abundance and constrains predation rate, slightly increasing egg mass should simultaneously allow offspring to feed on more prey and escape from more predators. However, the benefits of larger offspring would be relatively smaller for sit-and-wait predators because (i) due to their lower mobility, encounters with other predators are less common, and (ii) they usually employ a set of alternative hunting strategies that help to subdue relatively larger prey. On the other hand, for active predators, which need to confront prey as they find them, body-size differences may be more important in subduing prey. This difference in benefits should lead to the evolution of larger egg sizes in active-hunting relative to sit-and-wait predators. This prediction was confirmed by a phylogenetically controlled analysis of 268 spider species, supporting the view that the structure of ecological networks may serve to predict relevant selective pressures acting on key life history traits.

Original languageEnglish
Pages (from-to)1225-1233
Number of pages9
JournalJournal of Evolutionary Biology
Issue number6
StatePublished - Jun 1 2015

Bibliographical note

Publisher Copyright:
© 2015 European Society For Evolutionary Biology.


  • Egg size
  • Food web
  • Foraging theory
  • Mobility
  • Selection
  • Spiders
  • Trade-off

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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