Evol Ecol Res 15: 757-768 (2013)     Full PDF if your library subscribes.

Respect for property rights: when does it pay to defend territory?

Douglas W. Morris and Jody T. MacEachern

Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada

Correspondence: D.W. Morris, Department of Biology, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada.
e-mail: douglas.morris@lakeheadu.ca


Question: Should habitat-selecting individuals respect the property rights of territory holders or challenge them for ownership?

Definitions: Ideal despotic individuals challenge others for high-quality territories and defend them against rivals. Ideal pre-emptive individuals seek only unoccupied space and surrender it when challenged by despots.

Approach: Computer simulations of an evolutionary game between ideal despotic and ideal pre-emptive habitat selectors.

Features of the model: Individuals of each strategy choose between two habitats. Pure strategies grow for 1000 generations after which one individual possessing the alternative strategy is allowed to invade. If the invasion fails within 10 generations, invasion is attempted again with twice as many individuals (maximum of four attempts with 1, 2, 4, and 8 individuals respectively). Each simulation is repeated 99 times.

Ranges of key variables: Habitat quality: mean population growth rate = 1 vs. 1.5; standard deviation = 0.25; sampling effort = 10; defence costs = 0–0.5 in increments of 0.01; challenge cost = 0.02; search cost = 0.02; stochastic frequency = 2 or 3; stochastic mortality = 2–4.

Conclusions: The two strategies frequently co-existed. The pre-emptive strategy outperformed the despotic strategy. Pre-emptive individuals gained additional advantages when resident, and when defence costs were high. Thus, real populations of territorial species are rather likely to also exhibit mixed strategies where respect for property rights may trump overt conflict.

Keywords: co-existence, evolutionary game, habitat selection, ideal despotic distribution, ideal pre-emptive distribution, mixed strategies, territory.

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