title: When is dispersal for dispersal? Unifying marine and terrestrial perspectives.
abstract: Recent syntheses on the evolutionary causes of dispersal have focused on dispersal as a direct adaptation, but many traits that influence dispersal have other functions, raising the question: when is dispersal 'for' dispersal? We review and critically evaluate the ecological causes of selection on traits that give rise to dispersal in marine and terrestrial organisms. In the sea, passive dispersal is relatively easy and specific morphological, behavioural, and physiological adaptations for dispersal are rare. Instead, there may often be selection to limit dispersal. On land, dispersal is relatively difficult without specific adaptations, which are relatively common. Although selection for dispersal is expected in both systems and traits leading to dispersal are often linked to fitness, systems may differ in the extent to which dispersal in nature arises from direct selection for dispersal or as a by-product of selection on traits with other functions. Our analysis highlights incompleteness of theories that assume a simple and direct relationship between dispersal and fitness, not just insofar as they ignore a vast array of taxa in the marine realm, but also because they may be missing critically important effects of traits influencing dispersal in all realms.
authors.affiliation: Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32308, U.S.A.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Burgess
authors.affiliation: Department of Environmental Science and Policy, University of California, One Shields Ave, Davis, CA 95616, U.S.A.
authors.forename: Marissa L
authors.initials: ML
authors.lastname: Baskett
authors.affiliation: Department of Evolution and Ecology, University of California, One Shields Ave, Davis, CA 95616, U.S.A.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Grosberg
authors.affiliation: Bodega Marine Laboratory, University of California, 2099 Westside Rd, Davis, CA 94923, U.S.A.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Morgan
authors.affiliation: Friday Harbor Laboratories, University of Washington, 620 University Rd, Friday Harbor, WA 98250, U.S.A.
authors.forename: Richard R
authors.initials: RR
authors.lastname: Strathmann
mesh_terms: D000222:Adaptation, Physiological; D063147:Animal Distribution; D000818:Animals; D059001:Aquatic Organisms; D005075:Biological Evolution; D012641:Selection, Genetic
keywords: adaptation; complex life cycles; dispersal; movement; multivariate selection