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.

Nutritional imbalance suppresses migratory phenotypes of the Mongolian locust ( Oedaleus asiaticus )

“…Moreover, we found that migratory phenotypes were more susceptible to diet quality variation, which may result in the non-migratory phenotypes having greater fitness than migratory phenotypes when the nutritional quality of host plants is poor. Our findings support recent calls for a renewed study of migratory and dispersal reaction norms [5] to aid in developing an understanding of the regulation and evolution of migratory and dispersal behaviours [6]. …”

“…Migration is often viewed as an adaptation to shifting or patchy environments, with migration being induced to allow individuals to seek out better habitats at a given time and life stage [1,5]. However, why and how migration evolves across taxa and the environmental factors that induce migration remain opaque [5,6]. …”

Nearshore Larval Retention and Cross-Shelf Migration of Benthic Crustaceans at an Upwelling Center

“…This deeply affects the ecology, evolution and management of species in upwelling regimes. More larval retention should increase coupling between stock and recruitment, local adaptation and local benefits of marine protected areas as well as vulnerability of marine protected areas to overfishing and other disturbances (Strathmann et al, 2002;Sanford and Kelly, 2011;Burgess et al, 2014Burgess et al, , 2016.…”

Shoreward swimming boosts modeled nearshore larval supply and pelagic connectivity in a coastal upwelling region

“…However, recent advances in determining dispersal distances, such as parentage analysis and natural elemental markers, have provided more persuasive evidence that larvae stay closer to home than is widely believed (Burgess et al, 2014(Burgess et al, , 2016Levin, 2006;Morgan, 2014, in press;Swearer et al, 2002;Thorrold et al, 2002Thorrold et al, , 2007.…”