Ecologia alimentar e comportamento de forrageamento de Ameivula aff. ocellifera (Squamata: Teiidae) em área de caatinga do nordeste do Brasil
This study investigated the influence of intrinsic and extrinsic factors on the feeding ecology and foraging behavior of the whiptail lizard Ameivula aff. ocellifera, a new species widely distributed in the Brazilian Caatinga, and that is in process of description. In attendance to the objectives, t...
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Formato: | Dissertação |
Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/17344 |
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Resumo: | This study investigated the influence of intrinsic and extrinsic factors on the feeding ecology
and foraging behavior of the whiptail lizard Ameivula aff. ocellifera, a new species widely
distributed in the Brazilian Caatinga, and that is in process of description. In attendance to the
objectives, the Dissertation was structured in two chapters, which correspond to scientific
articles, one already published and the other to be submitted for publication. In Chapter 1
were analyzed the general diet composition, the relationship between lizard size and prey size,
and the occurrence of sexual and ontogenetic differences in the diet. Chapter 2 contemplates a
seasonal analysis of diet composition during two rainy seasons interspersed with a dry season,
and the quantitative analysis of foraging behavior during two distinct periods. The diet
composition was determined through stomach analysis of lizards (N = 111) collected monthly
by active search, between September 2008 and August 2010, in the Estação Ecológica do
Seridó (ESEC Seridó), state of Rio Grande do Norte. Foraging behavior was investigated
during a rainy and a dry month of 2012 also in ESEC Seridó, by determining percent of time
moving (PTM), number of movements per minute (MPM) and prey capture rate by the lizards
(N = 28) during foraging. The main prey category in the diet of Ameivula aff. ocellifera was
Insect larvae, followed by Orthoptera, Coleoptera and Araneae. Termites (Isoptera) were
important only in numeric terms, having negligible volumetric contribution (<2%) and low
frequency of occurrence, an uncommon feature among whiptail lizards. Males and females
did not differ neither in diet composition nor in foraging behavior. Adults and juveniles
ingested similar prey types, but differed in prey size. Maximum and minimum prey sizes were
positively correlated with lizard body size, suggesting that in this population individuals
experience an ontogenetic change in diet, eating larger prey items while growing, and at the
same time excluding smaller ones. The diet showed significant seasonal differences; during
the two rainy seasons (2009 and 2010), the predominant prey in diet were Insect larvae,
Coleoptera and Orthoptera, while in the dry season the predominant prey were Insect larvae,
Hemiptera, Araneae and Orthoptera. The degree of mobility of consumed prey during the
rainy seasons was lower, mainly due to a greater consumption of larvae (highly sedentary
prey) during these periods. Population niche breadth was higher in the dry season, confirming
the theoretical prediction that when food is scarce, the diets tend to be more generalized.
Considering the entire sample, Ameivula aff. ocellifera showed 61,0 ± 15,0% PTM, 2,03 ±
0,30 MPM, and captured 0,13 ± 0,14 per minute. Foraging mode was similar to that found for
other whiptail lizards regarding PTM, but MPM was relatively superior. Seasonal differences were verified for PTM, which was significantly higher in the rainy season (66,4 ± 12,1) than
in the dry season (51,5 ± 15,6). It is possible that this difference represents a behavioral
adjustment in response to seasonal variation in the abundance and types of prey available in
the environment in each season |
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