Population dynamics of pampas mice (<Emphasis Type="Italic">Akodon azarae</Emphasis>): signatures of competition and predation exposed through time-series modeling |
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Authors: | Marcelo Javier Kittlein |
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Institution: | (1) Departamento de Biología, Facultad de Ciencias Exáctas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250 4to piso, 7600 Mar del Plata, Argentina |
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Abstract: | The ability of four mechanistic population models to mirror a 5-year time series of seasonal densities of the pampas mouse,
Akodon azarae, from central Argentina, is evaluated in this paper. The different models included, singly or in combination, the effects
of a putative competitor and a specialist predator on the dynamics of pampas mice. The most simple model, a logistic single-species
stochastic differential equation, failed to fit the observed time series satisfactorily (R
model2 = 0.36), while models including interspecific effects gave much better fits with increasing model complexity (competition
R
model2 = 0.71, predation R
model2 = 0.62, competition and predation R
model2 = 0.83). Using Akaike’s information criterion, the competition model was selected as the best alternative with regard to
model fit and model complexity. Synthetic time-series probes obtained by simulations from the parameterized stochastic mechanistic
models were significantly different and indicated the competition plus predation model as a slightly better alternative than
the competition model. The differences between the two methods for selecting models indicate that the incorporation of predation
only slightly improves the match between the predicted and observed time series and that this slight improvement is not sufficient
to override the increase in model complexity. Competition thus seems to play a more important role than predation in shaping
the population dynamics of pampas mice. |
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Keywords: | Argentina Interspecific interactions Models Population dynamics Small mammals |
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