Coloração e seleção sexual em Tropidurus hispidus
In this study our goals were to address the following issues: Are there differences in coloration between males and females of Tropidurus hispidus? Do females use color traits to choose between mates? Does male coloration predict the outcome of agonistic encounters? Tropidurus hispidus Spix (1825),...
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| Formato: | doctoralThesis |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/24372 |
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| Resumo: | In this study our goals were to address the following issues: Are there differences in coloration between males and females of Tropidurus hispidus? Do females use color traits to choose between mates? Does male coloration predict the outcome of agonistic encounters? Tropidurus hispidus Spix (1825), the larger species of the Torquatus group. Tropidurus are diurnal, extremely abundant, heliophiles, sit-and-wait foragers, and territorial lizards occurring predominantly in open areas. We used a spectrophotometer to measure color variables and visual modeling using visual sensitivity data for Podarcis mularis. This data was used to answer the first question. To answer questions 2 and 3 we performed two controlled experiments with size-paired males. First, we conducted a female mate-choice experiment where males were placed in a terraria enclosure with three separated parts. We assigned each male to a compartment in which they did not have mutual visual contact. Next, we assigned females to the third compartment that enabled visual contact to both the males. The second experiment consisted of an agonistic interaction set up where we placed a pair of males in a single terraria enclosure for 30 min. During the experiment period we recorded behavioral displays in order to determine winners of each trial. Separately, we used color variables to differentiate males from females. Our first results clearly showed that T. hispidus exhibits sexual dichromatism and that it is perceived as conspecific. Of the eleven areas of the body used to compare males and females, nine showed significant differences. For the dorsal region and head, the red chroma is the variable that most discriminates males from females. While for the ventral region of the thigh, cloaca, flank, belly and throat the glow is the one that best distinguishes males from females. For the base of the tail the tint better discriminates. The UV chroma in the ventral region of the tail base also distinguishes the sexes. The visual modeling showed that these differences are likely perceived by other lizards, confirming spectrophotometry data. In the experiment of choice by the females the region and the variable that discriminated best chosen and not chosen were respectively thigh ventral and chroma 8. For the competition experiment between the males the belly and collar regions, as well as the blue, 3 And 8 chroma variables, better discriminated winners and losers. This shows us that the difference between males and females goes beyond those described in literatures and that coloring plays an important role in inter and intra-sexual competition. With this we hope to have contributed to a better understanding of the evolution of the signal design and how the intra- and intersexual selection act in this process in T. hispidus. |
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