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| Author(s): |
Juliana Gusson Roscito
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2010-11-29 |
| Examining board members: |
Miguel Trefaut Urbano Rodrigues;
Marcelo Rodrigues de Carvalho;
Tiana Kohlsdorf;
Chao Yun Irene Yan;
Hussam El Dine Zaher
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| Advisor: | Miguel Trefaut Urbano Rodrigues |
| Abstract | |
The evolutionary history of the Gymnophthalmini (Gymnophthalmidae) is characterized by morphological modifications related to the evolution of a snake-like body plan adapted to fossorial habits. Fossorial snake-like species show adaptations, especially body lengthening and limb reduction, that are frequently observed throughout Squamate lineages. Pattern formation is coordinated by a complex regulation network that acts during embryonic development, and subtle changes to this network may result in drastic phenotypic modifica-tions, leading to evolutionary variation in body plans. In this context, Squamates represent an excellent research model since several distant related species show similar (and phylogenetically independent) adaptations to fossoriality, which may have originated trhough common developmental mechanisms, and can reflect, to some extent, a predominance of certain selective pressures acting upon developmental pathways. This work analyses the morphological aspect of embryonic development of five Gymnophthalmini species (Procellosaurinus tetradactylus, Vanzosaura rubricauda, Psilophthalmus paeminosus, Nothobachia ablephara e Calyptommatus sinebrachiatus) establishing criteria for the embryonic staging through external morphology, and analysing the development of cartilage and bone in the skull, and axial and appendicular systems in a comparative background, associating morphology to life habits. Fossorial life exerts great pressure upon the body, which demands an adaptative response in order to overcome this sort of impact. Thus, fossorial animals shows a robust skull, with bones tightly articulated as to protect the brain and sense organs, an elongated body for ondulatory locomotion and reduced limbs that do not actively participate in locomotion. Preliminary data on the possible developmental processes responsible for limb reduction and body elongation in the fossorial lineage are shown, and are discussed on the light of evolutionary developmental biology. (AU) | |