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Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi
The study of geographic variation and its causes in the phenotypes of animals elucidates how evolutionary processes generate biodiversity. This thesis attempts to uncouple the relative contributions of adaptive and neutral mechanisms to population divergence in African horseshoe bats (genus Rhinolop...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2017
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| _version_ | 1867613240288083968 |
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| access_status_str | Open Access |
| author | Mutumi, Gregory L |
| author2 | Jacobs, David S |
| author_browse | Jacobs, David S Mutumi, Gregory L |
| author_facet | Jacobs, David S Mutumi, Gregory L |
| author_sort | Mutumi, Gregory L |
| collection | Thesis |
| description | The study of geographic variation and its causes in the phenotypes of animals elucidates how evolutionary processes generate biodiversity. This thesis attempts to uncouple the relative contributions of adaptive and neutral mechanisms to population divergence in African horseshoe bats (genus Rhinolophus). The two species were sampled from their distributional ranges within southern Africa and several morphometric and echolocation parameters were taken. The relative contributions of adaptation and drift were first tested (Chapter 2) using the Lande's model. It was hypothesised that adaptation would predominate in the diversification of the two horseshoe bats owing to the flight-echolocation and diet-echolocation adaptive complexes that intricately tie these two species to environmental conditions. Selection was also hypothesised to be stronger in Rhinolophus swinnyi because it uses higher frequency sound which is more sensitive to atmospheric conditions. The hypotheses were tested using a combination of soft tissue parameters (Chapter 2) and hard tissue parameters (Chapter 3), i.e., 3D scanned skulls analysed using 3D geometric morphometrics. To reconstruct the selective forces, linear mixed-effects models were used to regress climatic variables against echolocation call signals (Chapter 4) based on two hypotheses, the Sensory Drive and the James' Rule as a guide. The Lande's model (Chapter 2 and 3) showed that drift had a minimal effect to the variation of body parameters and echolocation and that selection was stronger on echolocation than on morphometric parameters. Additionally selection was differentially exerted across different localities and between the two species, making the relative roles of selection and drift context specific. Climatic variables (mean annual temperature and relative humidity) were inversely related to the variation in echolocation signals (Chapter 4) within each species. Body size was unrelated to the observed variation, which provided evidence that echolocation signals did not vary as a result of the body size/climate relationship proposed by James' Rule. Bats rely on both flight and echolocation to survive and reproduce, systems that have to track local habitats closely to perform optimally. Hence selection plays a pivotal role in their diversification. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/22907 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:58.612Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/22907 Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi Mutumi, Gregory L Jacobs, David S Winker, Henning Biological Sciences The study of geographic variation and its causes in the phenotypes of animals elucidates how evolutionary processes generate biodiversity. This thesis attempts to uncouple the relative contributions of adaptive and neutral mechanisms to population divergence in African horseshoe bats (genus Rhinolophus). The two species were sampled from their distributional ranges within southern Africa and several morphometric and echolocation parameters were taken. The relative contributions of adaptation and drift were first tested (Chapter 2) using the Lande's model. It was hypothesised that adaptation would predominate in the diversification of the two horseshoe bats owing to the flight-echolocation and diet-echolocation adaptive complexes that intricately tie these two species to environmental conditions. Selection was also hypothesised to be stronger in Rhinolophus swinnyi because it uses higher frequency sound which is more sensitive to atmospheric conditions. The hypotheses were tested using a combination of soft tissue parameters (Chapter 2) and hard tissue parameters (Chapter 3), i.e., 3D scanned skulls analysed using 3D geometric morphometrics. To reconstruct the selective forces, linear mixed-effects models were used to regress climatic variables against echolocation call signals (Chapter 4) based on two hypotheses, the Sensory Drive and the James' Rule as a guide. The Lande's model (Chapter 2 and 3) showed that drift had a minimal effect to the variation of body parameters and echolocation and that selection was stronger on echolocation than on morphometric parameters. Additionally selection was differentially exerted across different localities and between the two species, making the relative roles of selection and drift context specific. Climatic variables (mean annual temperature and relative humidity) were inversely related to the variation in echolocation signals (Chapter 4) within each species. Body size was unrelated to the observed variation, which provided evidence that echolocation signals did not vary as a result of the body size/climate relationship proposed by James' Rule. Bats rely on both flight and echolocation to survive and reproduce, systems that have to track local habitats closely to perform optimally. Hence selection plays a pivotal role in their diversification. 2017-01-23T07:53:44Z 2017-01-23T07:53:44Z 2016 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/22907 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Biological Sciences Mutumi, Gregory L Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| thesis_degree_str | Doctoral |
| title | Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| title_full | Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| title_fullStr | Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| title_full_unstemmed | Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| title_short | Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi |
| title_sort | geographic variation in the phenotypes of two sibling horseshoe bats rhinolophus simulator and r swinnyi |
| topic | Biological Sciences |
| url | http://hdl.handle.net/11427/22907 |
| work_keys_str_mv | AT mutumigregoryl geographicvariationinthephenotypesoftwosiblinghorseshoebatsrhinolophussimulatorandrswinnyi |