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Title
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Manoeuvrability and the anatomy of the inner ear in lacertid lizards : an ecological approach
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Author
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Abstract
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| In this thesis, we studied the anatomy of the lacertid vestibular system as well as the manoeuvring capacities of lacertid lizards. When we investigated the interaction between vestibular system size, head size and microhabitat use, we found that lizards with smaller heads housed disproportionally large ears for their size. Since sensitivity of the vestibular system relies on the circulation of the endolymph inside the canals and is positively related to size, a large vestibular system in small animals would ensure the functioning of the ear. The microhabitat lizards occupy did not have an impact on this size relationship, because of spatial constraints of the skull. The shape analysis showed that species living in simple microhabitats possessed more anatomical adaptations linked to enhanced sensitivity than species in more complex habitats, suggesting that the former may benefit from increased sensitivity due to a higher visibility to predators. Then, we tested the manoeuvrability, turning capacity and running performance of male and female Podarcis erhardi lizards, running on a zigzag and on a straight line racetrack. We used four P. erhardii populations situated at the Greek archipelago. In 2014 lizards were captured from the island of Naxos, Greece (site of Alyko) and were translocated to three experimental islets. The analyses on the microhabitat structure showed that the site of Alyko differed significantly in microhabitat structure from the three islets being covered more by sand rather than rocks and vegetation. We found that lizards from Alyko avoided areas lacking completely in shelters, a behaviour probably relating to thermoregulation and predator avoidance. The experiments performed for the population (males and females) of Alyko two years after the translocation (in 2016) showed that females turned more succesfully than males, however, a similar locomotor performance was observed for both sexes. We found that lizards on the experimental islands increased their size after their introduction, however their locomotor performance did not significantly differ from the performance of the individuals sampled in Alyko, 2016. We found that the average turning speed increased during the first two years of colonization, however two years later, it decreased. Islet lizards became better in avoiding collisions with the walls of the racetrack with time, and used more controlled manoeuvring strategies. We hypothesize that the complexity of the structural habitat on the experimental islets selects for improved manoeuvring capacities, and the lack of predation pressure selects for the use of slower manoeuvring in 2018. |
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Language
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English
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Publication
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Antwerp
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University of Antwerp, Faculty of science, Department of Biology
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2020
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Volume/pages
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272 p.
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Note
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Goyens, Jana [Supervisor]
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Aerts, Peter [Supervisor]
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Full text (open access)
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