Thesis (M.S.)--University of Wisconsin -- La Crosse, 2009. / Includes bibliographical references (leaves 44-46)

D.Sc. (Zoology) / Please refer to full text to view abstract

M.Sc. (Zoology) / Please refer to full text to view abstract

Distribution patterns and levels of genetic diversity in extant taxa are a product of complex palaeogeographic processes and climatic oscillations as well as the species’ intrinsic ecological adaptations. The Cape Floristic Region of South Africa presents a unique system for studying the processes that promote species diversification and distribution patterns. This region has a high degree of endemism of both terrestrial and aquatic biota and is clearly isolated from neighbouring areas by the Cape Fold Mountains and the Great Escarpment. The objective of this study was to firstly examine the ecology of freshwater fishes belonging to the genera Galaxias, Pseudobarbus and Sandelia in the south-western CFR. This was followed by an assessment of the genetic diversity of these taxa. Unique lineages were identified and their distribution was mapped. The work aimed to explore the role of the region’s complex palaeogeographic and climatic history as well as the role of the species’ ecological adaptations in driving lineage diversification and shaping contemporary distribution patterns. The four main components of the study can be summarised as follows: 1. Habitat associations of three widely distributed lineages of Galaxias zebratus Pseudobarbus burchelli and Sandelia capensis were evaluated at multiple localities in minimally disturbed mountain tributaries of the Breede, Duiwenhoks and Goukou River systems. The lineages have distinct habitat associations which were related to differences in their morphological traits. The slender-bodied Galaxias ‘nebula’ and the fusiform-shaped Pseudobarbus ‘Breede’ are capable of exploiting upper reaches with faster water velocity. By contrast, the laterally compressed Sandelia ‘eastern’ is restricted to lower reaches, making this lineage more susceptible to a wide array of impacts. 2. A recently discovered lineage of Galaxias zebratus, (Galaxias ‘nebula’), was found to be capable of tolerating emersion for a prolonged period of time. This is the first time that such capabilities have been documented in an African galaxiid. These adaptations have implications for the interpretation of Galaxias ‘nebula’s wide distribution range. 3. The phylogeography of Galaxias ‘nebula’ across its entire distribution range was investigated using two mitochondrial genes (cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b)). This lineage has a complex evolutionary history that was influenced by both intrinsic and extrinsic factors. Rare events such as episodic drainage connections during Pleistocene and Holocene pluvial periods, possibly augmented by river confluences during periods of lower sea-levels and river capture events seem to be the most credible explanation for the extensive contemporary distribution and the relatively shallow genetic divergence between different river systems. 4. Mitochondrial cyt b sequences were used (i) to assess genetic diversity in G. zebratus, P. burchelli and S. capensis from the south-western CFR and (ii) to determine the roles of intrinsic ecological adaptations and extrinsic landscape and climatic changes in promoting genetic diversification and shaping present day distribution patterns of lineages in the three taxa. Marine incursions during periods of major sea-level transgressions are proposed to have isolated populations in upland refugia, thereby driving allopatric divergence in these species. Subsequent connections of rivers during wetter periods and lower sea-levels are proposed to have facilitated post-speciation dispersal of lineages to attain present day distribution patterns. While detailed morphological studies and further genetic analysis are needed to substantiate the taxonomic status of the newly discovered lineages of Galaxias zebratus, Pseudobarbus burchelli and Sandelia capensis, results of the present study indicate that the south-western CFR represents a previously unrecognised centre of freshwater fish diversity and microendemism in the broader Cape Floristic Region. Accurate identification of lineages and comprehensive mapping of their distribution is a fundamental pre-requisite for ecological studies, assessing conservation status and implementation of appropriate conservation measures.

A Geographic Information Systems (GIS) atlas of southern African freshwater fish was developed for the SADC countries from natural history collection specimens, hydrological, topographical and climatological data. The primary purpose of the development of the atlas of freshwater fish was the construction of a practical framework to transform vast amounts of existing biological data for use in research and management of aquatic resources. The database of freshwater fish collection specimens that was incorporated into the atlas, was developed in association with ALCOM (Aquatic Resources Management for Local Community Development Programme). The development of advanced computing and GIS technology has increased the scope of biological atlas projects by facilitating the integration of large amounts of spatial data to produce derived databases for specific applications. The atlas of freshwater fish was constructed using TNTmips GIS software as the most practical system available for managing and analysing biological data with a spatial component. The atlas contains 35 180 comprehensive distribution records of 735 species of fish. It has many applications as an inventory of ichthyofaunal spatial biodiversity, including those of conservation planning, environmental assessment and biogeographic research. Biogeographic studies have traditionally been subjective due to the logistical problems of working with large amounts of distribution data, although some small-scale quantitative research has been carried out in the past. The content of the atlas of freshwater fish is tested with respect to these previous studies, on known patterns of freshwater fish distributions, and the analytical capability of the atlas is tested and demonstrated with some new preliminary approaches to the analysis of freshwater fish distributions in southern Africa.

No description available.

The aims of this study were firstly to observe the breeding behaviour and embryo ology. and then to identify factors affecting the reproductive biology of the Australian native pseudomtlgilid Pseudomugil signifer (pacific blue-eye) and the impact upon it of the presence of the exotic species Gambusia holbrooki (eastern gambusia). Six species of the genus Pseudomugil, and the related Scaturiginichthys venneilipinnis, are found on the Australian continent. The normal breeding behaviour, egg surface morphology and embryology of four species of Pseudomugil (P. signijer, P. genrudae, P. tenellus and P. mellis) were first investigated, using aquarium and microscopic (light and S.E.M.) studies. The four species were divided into two groups: P. signifer and P. mellis; and P. tenellus and P. gertrudae. The study provided further evidence for the view that the embryology of the genus Pseudomugil differs markedly from that of members of the family Melanotaeniidae, with which the pseudomugilids have previously been grouped. The seasonal pattern of gonadal function in P. signifer, both in the field and in aquariums, was then investigated for populations of P. signifer from the Sydney region. It was found that P. signifer bred over the spring and summer months, commencing breeding as the temperature and daylength increased, and declining in breeding activity as daylength and temperature declined. There was no substantial difference in the pattern of reproductive activity between wild and captive stocks of P. signifer in the populations used. The impact of the presence of the introduced G. holbrooki on P. signifer was then examined, first in open-air tank experiments , and then in the field. In the tank experiments the exotic species profoundly affected the breeding of the native species. When G. holbrooki were in the tanks P. signifer did not gain weight or grow in total length (except for females given supplementary feed); ovarian weight and fecundity was greatly reduced and the ovaries were morphologically undeveloped. No eggs from P. signifer were observed in tanks which also housed G. holbrooki. G. holbrooki were observed to actively hunt and eat young P. signifer and to nip the caudal fins of adult P. signifer. The results indicate clearly, that at least in a captive situation, the presence of the exotic species has a very deleterious effect on breeding and hence possible survival, of a native population. A pilot study conducted at the same time as the harvest of the second tank study did not reveal such drastic consequences. However, even in the less confined field situation, some evidence of an interrelation between water quality, numbers of P. signifer and numbers of G. holbrooki were seen in one disturbed site (Home bush Bay). These findings suggest that a newly designed field experiment based on data collected from the power analysis of the pilot study could clarify whether G. holbrooki adversely affects P. signifer in the wild. The information gained from these studies can be used in the management of P. signifer in the wild, and serve as a model of the possible effects upon other native species.

The aims of this study were firstly to observe the breeding behaviour and embryo ology. and then to identify factors affecting the reproductive biology of the Australian native pseudomtlgilid Pseudomugil signifer (pacific blue-eye) and the impact upon it of the presence of the exotic species Gambusia holbrooki (eastern gambusia). Six species of the genus Pseudomugil, and the related Scaturiginichthys venneilipinnis, are found on the Australian continent. The normal breeding behaviour, egg surface morphology and embryology of four species of Pseudomugil (P. signijer, P. genrudae, P. tenellus and P. mellis) were first investigated, using aquarium and microscopic (light and S.E.M.) studies. The four species were divided into two groups: P. signifer and P. mellis; and P. tenellus and P. gertrudae. The study provided further evidence for the view that the embryology of the genus Pseudomugil differs markedly from that of members of the family Melanotaeniidae, with which the pseudomugilids have previously been grouped. The seasonal pattern of gonadal function in P. signifer, both in the field and in aquariums, was then investigated for populations of P. signifer from the Sydney region. It was found that P. signifer bred over the spring and summer months, commencing breeding as the temperature and daylength increased, and declining in breeding activity as daylength and temperature declined. There was no substantial difference in the pattern of reproductive activity between wild and captive stocks of P. signifer in the populations used. The impact of the presence of the introduced G. holbrooki on P. signifer was then examined, first in open-air tank experiments , and then in the field. In the tank experiments the exotic species profoundly affected the breeding of the native species. When G. holbrooki were in the tanks P. signifer did not gain weight or grow in total length (except for females given supplementary feed); ovarian weight and fecundity was greatly reduced and the ovaries were morphologically undeveloped. No eggs from P. signifer were observed in tanks which also housed G. holbrooki. G. holbrooki were observed to actively hunt and eat young P. signifer and to nip the caudal fins of adult P. signifer. The results indicate clearly, that at least in a captive situation, the presence of the exotic species has a very deleterious effect on breeding and hence possible survival, of a native population. A pilot study conducted at the same time as the harvest of the second tank study did not reveal such drastic consequences. However, even in the less confined field situation, some evidence of an interrelation between water quality, numbers of P. signifer and numbers of G. holbrooki were seen in one disturbed site (Home bush Bay). These findings suggest that a newly designed field experiment based on data collected from the power analysis of the pilot study could clarify whether G. holbrooki adversely affects P. signifer in the wild. The information gained from these studies can be used in the management of P. signifer in the wild, and serve as a model of the possible effects upon other native species.

Thesis (PhD (Veterinary Tropical Diseases, Veterinary Science))--University of Pretoria, 2009. / Includes bibliographical references. Also available in print format.

Glaciated areas offer a unique opportunity to study the dispersal of animals . During glaciation the fauna of glaciated areas was either destroyed or forced into ungla iated refugia. ..When the icesheets retreated the glaciated regions were open to reinvasion.