Linking spatial processes to life-history evolution of insect parasitoids

TY - JOUR

T1 - Linking spatial processes to life-history evolution of insect parasitoids

AU - Hoffmeister, T.S.

AU - Roitberg, B.D.

AU - Vet, L.E.M.

N1 - Reporting year: 2005 Metis note: 3643; CTE; MTI; file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs2005/Hoffmeister_ea_3643.pdf

PY - 2005

Y1 - 2005

N2 - 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]

AB - 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]

U2 - 10.1086/432563

DO - 10.1086/432563

M3 - Article

SN - 0003-0147

VL - 166

SP - E62-E74

JO - American Naturalist

JF - American Naturalist

IS - 3

ER -