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Frequency of Occurrence and Population-Dynamic Consequences of Different Forms of Density-Dependent Emigration

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dc.contributorJerome Goddard, jgoddard@aum.eduen_US
dc.creatorHarman, Rachel
dc.creatorGoddard, Jerome
dc.creatorShivaji, Ratnasingham
dc.creatorCronin, James
dc.description.abstractEmigration is a fundamental process affecting species' local, regional, and large-scale dynamics. The paradigmatic view in ecology is that emigration is density independent (DIE) or positive density dependent (1DDE). However, alternative forms are biologically plausible, including negative (2DDE), U-shaped (uDDE), and hump-shaped (hDDE) forms. We reviewed the empirical literature to assess the frequency of different forms of density-dependent emigration and whether the form depended on methodology. We also developed a reaction-diffusion model to illustrate how different forms of DDE can affect patch-level population persistence. We found 145 studies, the majority representing DIE (30%) and 1DDE(36%). However, we also regularly found 2DDE (25%) and evidence for nonlinear DDE(9%), including one case of uDDE and two cases of hDDE. Nonlinear DDE detection is likely hindered by the use of few density levels and small density ranges. Based on our models, DIE and 1DDE promoted stable and persistent populations. uDDE and 2DDE generated an Allee effect that decreases minimum patch size. Last, 2DDE and hDDE models yielded bistability that allows the establishment of populations at lower densities. We conclude that the emigration process can be a diverse function of density in nature and that alternative DDE forms can have important consequences for population dynamics.en_US
dc.publisherUniversity of Chicago Pressen_US
dc.relation.ispartofAMERICAN NATURALISTen_US
dc.rights©The Authors 2020. ©University of Chicago Press 2020. This is this the version of record published by the University of Chicago Press. It is made available under the CC-BY-NC-ND 4.0 license. Item should be cited as: Harman, Rachel R., Jerome Goddard, Ratnasingham Shivaji, and James T. Cronin. "Frequency of occurrence and population-dynamic consequences of different forms of density-dependent emigration." The American Naturalist 195, no. 5 (2020): 851-867.en_US
dc.subjectAllee effecten_US
dc.subjectmovement modelen_US
dc.subjectnegative densitydependenceen_US
dc.subjectpatch dynamicsen_US
dc.subjectpopulation persistenceen_US
dc.titleFrequency of Occurrence and Population-Dynamic Consequences of Different Forms of Density-Dependent Emigrationen_US
dc.type.genreJournal Article, Academic Journalen_US

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