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Linking spatial processes to life-history evolution of insect parasitoids

Hoffmeister, T.S. and Roitberg, B. D. and Vet, L.E.M. (2005) Linking spatial processes to life-history evolution of insect parasitoids. American Naturalist, 166, E62-E74. ISSN 0003-0147.

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Understanding the evolutionary transition from solitary to group living in animals is a profound challenge to evolutionary ecologists. A special case is found in insect parasitoids, where a tolerant gregarious larval lifestyle evolved from an intolerant solitary ancestor. The conditions for this transition are generally considered to be very stringent. Recent studies have aimed to identify conditions that facilitate the spread of a gregarious mutant. However, until now, ecological factors have not been included. Host distributions and life-history trade-offs affect the distribution of parasitoids in space and thus should determine the evolution of gregariousness. We add to current theory by using deterministic models to analyze the role of these ecological factors in the evolution of gregariousness. Our results show that gregariousness is facilitated through inversely density-dependent patch exploitation. In contrast, host density dependence in parasitoid distribution and patch exploitation impedes gregariousness. Numerical solutions show that an aggressive gregarious form can more easily invade a solitary population than can a tolerant form. Solitary forms can more easily invade a gregarious, tolerant population than vice versa. We discuss our results in light of exploitation of multitrophic chemical cues by searching parasitoids and aggregative and defensive behavior in herbivorous hosts. [KEYWORDS: clutch size ; density dependence ; competition ; foraging behavior ; spatial heterogeneity ; multitrophic interactions]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11727
Deposited On:23 Nov 2011 01:00
Last Modified:14 Oct 2013 15:41

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