Population, communication and habitat comparisons between the major gummivorous strepsirhines of Madagascar (phaner) and Cameroon (euoticus)
- Authors: Forbanka, Derick Nomuh
- Date: 2016
- Subjects: Adaptation (Biology) , Mammals -- Evolution , Mammals -- Behavior
- Language: English
- Type: Thesis , Doctoral , Zoology
- Identifier: http://hdl.handle.net/10353/15957 , vital:40567
- Description: The suborder Strepsirhini contains a large proportion of the living gummivorous mammal taxa, and includes two genera of specialist gummivores, Euoticus and Phaner, which present particularly interesting cases of convergent adaptive evolution in Africa and Madagascar, respectively. Although these genera are not closely related, they share several anatomical, behavioural and physiological specialisations associated with their diets, and despite their biogeographical separation, there seems to be substantial coincidence in their habitats and habits. Neither the ecology nor the systematics of Phaner and Euoticus has been the subject of much detailed research, and little is known of the conservation status of the genera. Even their specific diversity is unresolved. In this study I investigated and compared aspects of their ecology at both a macro-and a microhabitat scale, including wild populations of all groups within the two genera that have been accorded species status in recent field guides and systematic reviews. I also studied aspects of their social communication behaviour as clues to their species-level diversity. Species and their formation (or speciation) have inspired a great deal of evolutionary research, but remain contentious issues in evolutionary biology. This is due both to the difficulties inherent in inferring the details of a dynamic biological process that occurred over some time in the past from the recent, relatively static patterns of variation observed, as well as the limited consensus among biologists in identifying such patterns. It is therefore important to distinguish the kinds of patterns in nature that are predicted by different views of species and speciation, and also to see how well these predictions fare when applied to the speciation patterns found in strepsirhine primates. Theories of speciation cannot be separated from species concepts, and one concept widely supported in primatology is the Recognition Concept of species because of its heuristic nature. The Recognition Concept is based on Specific-mate Recognition Systems (SMRS). I focussed on SMRS features of Euoticus and Phaner, loud call specificity, and species’ preferred habitats. My results provided some support for the distinctiveness of currently identified species, although this was not clear-cut. Population densities of both Phaner and Euoticus appear to have declined in recent years, even though both Phaner and Euoticus appear to be well adapted to both primary and secondary forest, and exhibit ecological plasticity. Statistically some loud call parameters vary among the putative species of the genus Phaner and not Euoticus. Phaner pallescens at Kirindy, Madasgascar was clearly able to discriminate loud calls of its own population from other proposed species within the genus. Most loud call parameters did not show any statistical degradation with increasing distance. A crucial finding of my study was that the two lineages are not only convergent in terms of dietary and locomotor aspects of their ecology, but also in the structures of their loud calls. The environmental adaptation of communication systems is often overlooked when studying adaptive convergence, but my study indicates that acoustic properties are a crucial aspect of a species’ preferred habitat. The results of this study can be used to improve conservation planning, and also add to our understanding of the evolutionary history of strepsirhine primates.
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- Date Issued: 2016
Elephant feeding behaviour and forage offtake implications in the Addo Elephant National Park
- Authors: Lessing, Joan Susanna
- Date: 2007
- Subjects: Elephants -- South Africa -- Addo Elephant National Park , Elephants -- Behavior , Addo Elephant National Park (South Africa) , Mammals -- Behavior
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10712 , http://hdl.handle.net/10948/542 , http://hdl.handle.net/10948/d1012016 , Elephants -- South Africa -- Addo Elephant National Park , Elephants -- Behavior , Addo Elephant National Park (South Africa) , Mammals -- Behavior
- Description: Elephants, as megaherbivores and keystone species have major impacts, both positive and negative, on ecosystems such as the Subtropical Thicket of the Eastern Cape. The feeding behaviour of elephants was quantified so as to firstly determine the preferred feeding heights of elephants, and secondly to determine if feeding behaviour and impact varies with size and sex. The preferred feeding height was determined with experimental feeding trials. Feeding height, pluck size, foraging rate and the proportion of plant material discarded were used to test for differences between elephants of different sizes and sexes in the Addo Elephant National Park. The influence of plant growth form on sex-specific feeding was also considered. Elephants preferred to feed at the lowest heights. The preferred feeding height was not related to body size. A wide range of feeding heights was recorded including and extending beyond, both the preferred and maximum feeding height of co-existing indigenous browsers. There was no difference in feeding height between the sizes and sexes. In free ranging conditions, all elephants fed at levels above the preferred foraging height when browsing. There was no difference in feeding behaviour between the different sized elephants, or between males and females. Adult elephants however exhibited larger ranges of feeding heights, pluck sizes, foraging rates and intake rates, including the maximum and minimum values. Growth form influenced the feeding of male and female elephants differently. Elephant feeding behaviour appears to limit opportunities for resource partitioning by way of feeding height segregation. Elephants are also capable of dominating the browse resources available to co-existing browsers by removing large amounts of forage at lower heights. The extent of elephant impact seems to be comparable between sizes and sexes, although adults and especially larger males are often able to use foraging opportunities that other elephants can not effectively utilize. Findings suggest that the feeding heights of elephants are determined by forage availability and reflect the diet in terms of browse or grass. The findings can be used, together with browse inventory methods, to determine browse resources available to elephants, and can also be used to develop monitoring tools to assess the impacts of elephants on plants.
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- Date Issued: 2007