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Refuge availability and within-species differencesin cannibalism determine population variability and dynamics
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2013 (English)In: Ecosphere, ISSN 2150-8925, Vol. 4, no 100Article in journal (Refereed) Published
Abstract [en]

Theoretical studies show that both cannibalism and intraspecific resource competition canhave major effects on population dynamics. Cannibalistic intensity, offspring size, harvesting and refugeavailability are important factors affecting the interplay between cannibalism and competition. We studiedtwo populations of the common guppy (Poecilia reticulata) that differed in their cannibalistic voracity aswell as offspring size. We manipulated the availability of refuges for juveniles and harvesting intensity oflarge adults to investigate how these factors influenced the dynamics of the two populations.Overall population dynamics was mainly affected by the origin of the founder populations and thepresence of refuges. The population with a higher cannibalistic propensity and smaller offspring exhibitedhigher population variability, and the presence of refuges reduced cannibalism and stabilised the dynamicsin both populations. Harvest of large cannibalistic females destabilised the dynamics and causedextinctions of several populations without refuges. Both populations displayed cannibal-driven cycles withrepression of recruitment when no refuges were present. Cycle periods were shorter with refuges presentand the dynamics were more cohort like with synchronised peaks in density of vulnerable juveniles andcannibals. We suggest that increased number of refuging juveniles led to intensified resource competitionin the population. The harvest yield was low in the refuge treatments as few females grew large due toresource competition, leading to a small impact of harvesting in these treatments.

Place, publisher, year, edition, pages
2013. Vol. 4, no 100
Keyword [en]
cannibalism, coefficient of variation, competition, extinction, guppy, harvest, Poecilia reticulata, population dynamics, refuges, structural complexity
National Category
URN: urn:nbn:se:umu:diva-97953DOI: 10.1890/ES13-00105.1OAI: diva2:778212
Swedish Research Council
Available from: 2015-01-09 Created: 2015-01-09 Last updated: 2015-03-12Bibliographically approved

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