- Title
- An evolutionary study of legless skinks’ (Acontias Cuvier, 1817) head and vertebrae morphology
- Creator
- Evlambiou, Anthony Andreas
- ThesisAdvisor
- Edwards, Shelley
- ThesisAdvisor
- Conradie, Werner
- Subject
- Skinks South Africa
- Subject
- Acontias South Africa
- Subject
- Typhlosaurus South Africa
- Subject
- Acontias Morphology
- Subject
- Acontias Phylogeny
- Subject
- Acontias Evolution
- Subject
- Vertebrae
- Subject
- Skull Growth
- Subject
- Evolutionary developmental biology
- Date
- 2021-10
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10962/190690
- Identifier
- vital:45018
- Description
- Environmental factors and/or processes can produce differences in general shape between individuals or particular parts of individuals. Examples of these biological processes may include ontogenetic development, adaptation to local geographic factors, or long-term evolutionary diversification. An organism is not likely to be able to optimise a single structure for multiple purposes and so trade-offs are likely to occur. An example of such a structure is the cranium, as it can be used for multiple activities such as defensive and sexual behaviour, locomotion, prey capture, and ingestion. Morphological characteristics have historically been used in the description of species. Genetic analyses have gained popularity as species delineation techniques and have been particularly useful in identifying cryptic species, especially among morphological conserved species like legless skinks of the subfamily Acontinae (e.g. Acontias Cuvier, 1817 and Typhlosaurus Weigmann, 1834). However, completely doing away with morphological techniques during species descriptions is not the best option. Therefore, novel methods to identify species, especially those with similar body plans, are needed. In this dissertation, we explore the links between head shape and vertebral number to environmental pressures to determine whether the evolutionary process is driven by environmental pressures (soil or biome) or is retained through ancestry. A novel species/clade delineation linked to vertebral number is also investigated. Head shape was expected to have a close link to the environment and the number of vertebrae was expected to have a closer link to ancestry. The first chapter investigates the drivers behind Acontias head shape evolution using geometric morphometric techniques. We found that environmental pressures did affect the evolution of head shape especially in the “soil” and “biome” categories but further investigation is advised. The second chapter explores the viability of using vertebral counts as a novel method for species and/or clade delineation in Acontias and to determine whether vertebral number can be linked to the environment. Delineating species based on vertebral count is likely not an option, however, delineating clades proved to show promising results. A link between vertebral count and environment was found in Acontias with larger bodied species occurring in different environments to smaller body species. In conclusion, the genus Acontias is difficult to delineate morphologically. Genetic sequence analyses can indicate differences and delineate the species. Even though there were differences in morphology based on environmental factors, it is not sufficient to delineate this subfamily alone. Further research is advised and this dissertation provides a good basis to work with.
- Description
- Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Format
- computer, online resource, application/pdf, 1 online resource (122 pages), pdf
- Publisher
- Rhodes University, Faculty of Science, Zoology and Entomology
- Language
- English
- Rights
- Evlambiou, Anthony Andreas
- Rights
- Attribution 4.0 International (CC BY 4.0)
- Rights
- Open Access
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | EVLAMBIOU-MSC-TR21-229.pdf | 2 MB | Adobe Acrobat PDF | View Details Download |