Intrasexual Behaviors in the Nonnative Mediterranean House Gecko, Hemidactylus turcicus
Intrasexual Behaviors in the Nonnative Mediterranean House Gecko, Hemidactylus turcicus
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Date
2018-12
Authors
Warren, Clinton
Journal Title
Journal ISSN
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Publisher
University Honors College, Middle Tennessee State University
Abstract
Behavioral studies on introduced wildlife can provide valuable insight into its
mechanisms of dispersal, habitat use, and the interactions it holds with the native fauna
and flora. In this study, intrasexual (same-sex) behaviors of H. turcicus geckos were
observed through staged interactions using size-matched subjects in a lab arena.
Following baseline interaction tests, the same individuals underwent a topical treatment
of either testosterone or sesame oil (control) alone. I tested for behavioral differences
between the testosterone-treated and sesame oil-treated individuals, and I tested for an
effect of testosterone within subjects. Lastly, I tested for a sex difference in the frequency
of behaviors observed during the baseline tests. The behaviors recorded included
aggressive (e.g. pushups, tail wags, bites), submissive (freezes and retreats), and neutral
behaviors (e.g. approaches, licks, vocalizations). Behaviors expressed by testosterone treated
males did not differ from the sesame oil-treated males. The same was true in the
female treatment groups, where there was no difference between the treatments, and an
overall absence of most aggressive behaviors. Secondly, no significant differences were
found between the behaviors of the testosterone-treated subjects and their corresponding
baseline results in either sex. Together, these findings suggest that short-term elevations
of plasma testosterone do not have a direct influence on the expression of intrasexual
behaviors in H. turcicus. Longer durations of testosterone treatments (e.g., weeks rather than 3 days) could result in different effects on the behaviors of H. turcicus geckos, and
castration could also be used in future studies to test if a decrease in circulating plasma testosterone influences the expression of intrasexual behaviors of this House Gecko.
Lastly, males were found to be significantly more expressive in both aggressive and submissive behaviors, than the females in the baseline tests. This is consistent with
previous research on H. turcicus that reports males as being territorial and engaging in
agonistic encounters, but females often participate in communal nesting with members of
the same sex.
Description
Keywords
Gecko,
behavior,
invasive,
testosterone,
biology,
hormones,
lizard,
aggression