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Changes in dispersal during species' range expansions

Simmons, A.D. and Thomas, C.D. (2004) Changes in dispersal during species' range expansions. The American Naturalist, 164 (3). pp. 378-395. ISSN 0003-0147

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Explanations for rapid species’ range expansions have typically been purely ecological, with little attention given to evolutionary processes. We tested predictions for the evolution of dispersal during range expansion using four species of wing‐dimorphic bush cricket (Conocephalus discolor, Conocephalus dorsalis, Metrioptera roeselii, and Metrioptera brachyptera). We observed distinct changes in dispersal in the two species with expanding ranges. Recently colonized populations at the range margin showed increased frequencies of dispersive, long‐winged (macropterous) individuals, compared with longer‐established populations in the range core. This increase in dispersal appeared to be short‐lived because 5–10 years after colonization populations showed similar incidences of macroptery to populations in the range core. These changes are consistent with evolutionary change; field patterns persisted when nymphs were reared under controlled environmental conditions, and range margin individuals reared in the laboratory flew farther than range core individuals in a wind tunnel. There was also a reproductive trade‐off with dispersal in both females and males, which could explain the rapid reversion to lower rates of dispersal once populations become established. The effect of population density on wing morphology differed between populations from the range core (no significant effect of density) and expanding range margins (negative density dependence), which we propose is part of the mechanism of the changes in dispersal. Transient changes in dispersal are likely to be common in many species undergoing range expansion and can have major population and biogeographic consequences.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: York RAE Import
Date Deposited: 11 Feb 2009 14:15
Last Modified: 11 Feb 2009 14:15
Published Version: http://dx.doi.org/10.1086/423430
Status: Published
Publisher: University of Chicago Press
Identification Number: 10.1086/423430
URI: http://eprints.whiterose.ac.uk/id/eprint/7558

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