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Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos

BACKGROUND: The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals of the same species, respectively. As most lizards are territorial, aggregations increase...

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Autores principales: Vasconcelos, Raquel, Rocha, Sara, Santos, Xavier
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5228510/
https://www.ncbi.nlm.nih.gov/pubmed/28097049
http://dx.doi.org/10.7717/peerj.2802
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author Vasconcelos, Raquel
Rocha, Sara
Santos, Xavier
author_facet Vasconcelos, Raquel
Rocha, Sara
Santos, Xavier
author_sort Vasconcelos, Raquel
collection PubMed
description BACKGROUND: The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals of the same species, respectively. As most lizards are territorial, aggregations increase the probability of aggressive interactions among individuals, a density-dependent behaviour. METHODS: After some spurious observations of aggregation behaviour in the endemic Cabo Verde nocturnal gecko Tarentola substituta, we conducted a field-based study in order to thoroughly characterize it. We sampled 48 transects and 40 10 × 10 m quadrats on São Vicente Island to describe the incidence, size and composition of aggregations and to study the effect of gecko and refuge density, plus refuge quality, on refuge sharing. We hypothesize that when density of animals and scarcity of high-quality refuges is higher, lizards have increased probability of aggregating. We also predict a consistent pattern of size and composition of groups (male–female pairs, only one adult male per group) throughout the year if there is a selected behaviour to avoid agonistic interactions, and low thermal advantage to aggregating individuals. RESULTS: We present one of the first evidences of aggregation for Phyllodactylidae geckos. We found that T. substituta forms aggregations around 30–40% of the time, and that refuges are almost always shared by a female-male pair, sometimes with a juvenile, probably a mechanism to avoid aggressive interactions. We also observed that refuge sharing is dependent on refuge quality, as medium–large (thermally more stable and positively selected) rocks are shared much more frequently than small ones, but independent of adult sizes. Refuge sharing is also directly related to the density of geckos and inversely related to the density of high-quality refuges. We found no relation between body temperatures of geckos and refuge sharing when controlling the effect of rock/air temperature, suggesting that huddling does not improve thermoregulation. DISCUSSION: Our results suggest that in this harsh environment (rocks reach 46 °C) aggregation incidence is mainly driven by an ecological factor (scarcity of high-quality refuges) and its intersexual composition by social factors (avoidance of agonistic interactions by males, and possible increased reproductive success of the pair). This study sheds some light on the little explored gecko aggregation behaviour and other studies should follow.
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spelling pubmed-52285102017-01-17 Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos Vasconcelos, Raquel Rocha, Sara Santos, Xavier PeerJ Animal Behavior BACKGROUND: The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals of the same species, respectively. As most lizards are territorial, aggregations increase the probability of aggressive interactions among individuals, a density-dependent behaviour. METHODS: After some spurious observations of aggregation behaviour in the endemic Cabo Verde nocturnal gecko Tarentola substituta, we conducted a field-based study in order to thoroughly characterize it. We sampled 48 transects and 40 10 × 10 m quadrats on São Vicente Island to describe the incidence, size and composition of aggregations and to study the effect of gecko and refuge density, plus refuge quality, on refuge sharing. We hypothesize that when density of animals and scarcity of high-quality refuges is higher, lizards have increased probability of aggregating. We also predict a consistent pattern of size and composition of groups (male–female pairs, only one adult male per group) throughout the year if there is a selected behaviour to avoid agonistic interactions, and low thermal advantage to aggregating individuals. RESULTS: We present one of the first evidences of aggregation for Phyllodactylidae geckos. We found that T. substituta forms aggregations around 30–40% of the time, and that refuges are almost always shared by a female-male pair, sometimes with a juvenile, probably a mechanism to avoid aggressive interactions. We also observed that refuge sharing is dependent on refuge quality, as medium–large (thermally more stable and positively selected) rocks are shared much more frequently than small ones, but independent of adult sizes. Refuge sharing is also directly related to the density of geckos and inversely related to the density of high-quality refuges. We found no relation between body temperatures of geckos and refuge sharing when controlling the effect of rock/air temperature, suggesting that huddling does not improve thermoregulation. DISCUSSION: Our results suggest that in this harsh environment (rocks reach 46 °C) aggregation incidence is mainly driven by an ecological factor (scarcity of high-quality refuges) and its intersexual composition by social factors (avoidance of agonistic interactions by males, and possible increased reproductive success of the pair). This study sheds some light on the little explored gecko aggregation behaviour and other studies should follow. PeerJ Inc. 2017-01-10 /pmc/articles/PMC5228510/ /pubmed/28097049 http://dx.doi.org/10.7717/peerj.2802 Text en ©2017 Vasconcelos et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Animal Behavior
Vasconcelos, Raquel
Rocha, Sara
Santos, Xavier
Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title_full Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title_fullStr Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title_full_unstemmed Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title_short Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
title_sort sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos
topic Animal Behavior
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5228510/
https://www.ncbi.nlm.nih.gov/pubmed/28097049
http://dx.doi.org/10.7717/peerj.2802
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