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Population-level consequences of heterospecific density-dependent movements in predator-prey systems
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2014 (English)In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 342, 93-106 p.Article in journal (Refereed) Published
Abstract [en]

In this paper we elucidate how small-scale movements, such as those associated with searching for food and avoiding predators, affect the stability of predator-prey dynamics. We investigate an individual-based Lotka-Volterra model with density-dependent movement, in which the predator and prey populations live in a very large number of coupled patches. The rates at which individuals leave patches depend on the local densities of heterospecifics, giving rise to one reaction norm for each of the two species. Movement rates are assumed to be much faster than demographics rates. A spatial structure of predators and prey emerges which affects the global population dynamics. We derive a criterion which reveals how demographic stability depends on the relationships between the per capita covariance and densities of predators and prey. Specifically, we establish that a positive relationship with prey density and a negative relationship with predator density tend to be stabilizing. On a more mechanistic level we show how these relationships are linked to the movement reaction norms of predators and prey. Numerical results show that these findings hold both for local and global movements, i.e., both when migration is biased towards neighbouring patches and when all patches are reached with equal probability.

Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 342, 93-106 p.
Keyword [en]
Moment closure, Population dynamics, Spatial structure, Species coexistence, Stochastic processes
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-83171DOI: 10.1016/j.jtbi.2013.09.019OAI: oai:DiVA.org:umu-83171DiVA: diva2:665648
Funder
Swedish Research Council
Available from: 2013-11-20 Created: 2013-11-20 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Population-level consequences of spatial interactions
Open this publication in new window or tab >>Population-level consequences of spatial interactions
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

How is the nature of populations governed by the movement decisions made by their members? This is the core question in this thesis. To answer this question, I first assume that s movement decisions are based on conditions in their local environment. Then I derive mathematical relationships that distil the character of individual movement events, and relate the sum of these events to the dynamical properties of the population. I find that the fate of populations depend delicately on the way resident individuals relocate in response to local conditions. This general conclusion is supported by results in the four papers constituting this thesis.

In the first paper we derive a deterministic approximation of a stochastic individual-based spatial predator-prey model. We show how general types of movement behaviors either stabilise or destabilise predator-prey dynamics. Based on experimental data on movement behaviors, we conclude that predator-prey dynamics are stabilised if the prey species respond stronger to predator presence than the predatory species respond to prey.

In the second paper we derive a new type of functional response that arise when there is a behavioral spatial “race” between predators and prey. Although fundamentally different from classical functional responses, the induced density-dependencies in reproduction rates are similar to those in Holling’s type II and DeAngelis-Beddington’s functional responses.

In the third paper we perform a novel systematic investigation of density-dependencies in population growth-rates induced by the spatial covariance in empirical predator-prey systems. We categorise three types of density dependencies: “lagged”, “direct” and “independent”, and find direct and especially lagged density-dependencies to be common. We find that the density-dependencies in most cases are destabilising, which is at odds with the wide-spread view that spatial heterogeneity stabilises consumer-resource dynamics. We also find dependencies of prey density to be more common than of predator density.

In the forth paper we consider the evolution of cooperation. We formulate a stochastic individual-based group-formation process and show that profit-dependent group disengagement is evolutionarily stable and allows the emergence of stable cooperative communities.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2013. 29 p.
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-83194 (URN)978-91-7459-776-9 (ISBN)
Public defence
2013-12-12, KBC-huset, Lilla hörsalen, Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilSwedish Research Council Formas
Available from: 2013-11-21 Created: 2013-11-20 Last updated: 2015-07-03Bibliographically approved

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Sjödin, HenrikBrännström, ÅkeSöderquist, MårtenEnglund, Göran
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