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Slow natal dispersal across a homogeneous landscape suggests the use of mixed movement behaviours during dispersal in the Darwin's frog


Valenzuela-Sánchez, Andrés; Cayuela, Hugo; Schmidt, Benedikt R; Cunningham, Andrew A; Soto-Azat, Claudio (2019). Slow natal dispersal across a homogeneous landscape suggests the use of mixed movement behaviours during dispersal in the Darwin's frog. Animal Behaviour, 150:77-86.

Abstract

Dispersal is a key process in ecology and evolution. Both theoretical and empirical evidence in actively dispersing organisms support the general notion that the use of nearly straight dispersal paths is a highly efficient way to maximize dispersal success in heterogenous landscapes. In homogeneous landscapes, in contrast, the benefits of a straighter dispersal path could be outweighed by an increase in risk costs, favouring the evolution of tortuous dispersal paths resulting in a relatively slow dispersal. Empirical support for this theoretical prediction, however, has remained elusive. To explore this theoretical prediction, we studied the movement behaviour of the southern Darwin's frog, Rhinoderma darwinii, a fully terrestrial amphibian inhabiting a highly homogeneous environment (i.e. South American temperate forest). Using spatial capture–recapture data collected over a 4-year period in wild populations, in combination with statistical and simulation modelling, we found evidence of a slow natal dispersal lasting one year or more. In contrast, adults exhibited high site fidelity, having a median annual displacement of 3.64 m. A correlated random walk model produced synthetic distributions of juvenile annual displacement that were nearly identical to the empirical data, suggesting that a plausible explanation of juvenile dispersal is the use of routine movements (with high path tortuosity) over short temporal scales (<3 months) integrated over the year along a relatively straight dispersal path. We predict that for species living in homogenous landscapes, this behaviour likely reduces many of the costs associated with the transient stage of dispersal. Specifically, periods of routine movements might reduce risk costs (e.g. dying due to starvation or predation), while the integration of these periods along a straight line maximizes dispersal distance while minimizing energetic costs.

Abstract

Dispersal is a key process in ecology and evolution. Both theoretical and empirical evidence in actively dispersing organisms support the general notion that the use of nearly straight dispersal paths is a highly efficient way to maximize dispersal success in heterogenous landscapes. In homogeneous landscapes, in contrast, the benefits of a straighter dispersal path could be outweighed by an increase in risk costs, favouring the evolution of tortuous dispersal paths resulting in a relatively slow dispersal. Empirical support for this theoretical prediction, however, has remained elusive. To explore this theoretical prediction, we studied the movement behaviour of the southern Darwin's frog, Rhinoderma darwinii, a fully terrestrial amphibian inhabiting a highly homogeneous environment (i.e. South American temperate forest). Using spatial capture–recapture data collected over a 4-year period in wild populations, in combination with statistical and simulation modelling, we found evidence of a slow natal dispersal lasting one year or more. In contrast, adults exhibited high site fidelity, having a median annual displacement of 3.64 m. A correlated random walk model produced synthetic distributions of juvenile annual displacement that were nearly identical to the empirical data, suggesting that a plausible explanation of juvenile dispersal is the use of routine movements (with high path tortuosity) over short temporal scales (<3 months) integrated over the year along a relatively straight dispersal path. We predict that for species living in homogenous landscapes, this behaviour likely reduces many of the costs associated with the transient stage of dispersal. Specifically, periods of routine movements might reduce risk costs (e.g. dying due to starvation or predation), while the integration of these periods along a straight line maximizes dispersal distance while minimizing energetic costs.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Uncontrolled Keywords:amphibian, natal dispersal
Language:English
Date:1 April 2019
Deposited On:20 Mar 2019 17:12
Last Modified:25 Sep 2019 00:29
Publisher:Elsevier
ISSN:0003-3472
OA Status:Closed
Publisher DOI:https://doi.org/10.1016/j.anbehav.2019.01.026

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