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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Species diversity, habitat utilization and blood parasites of amphibians in and around Ndumo Game Reserve / Edward Charles Netherlands

Netherlands, Edward Charles January 2014 (has links)
Ndumo Game Reserve is the only officially protected area within the Phongolo Floodplain; an area in the northern parts of KwaZulu-­‐Natal known to boast a rich diversity of amphibians, thus becoming one of the focal areas for this study. The study’s aim was to monitor and record amphibian diversity, as well as associated blood parasite biodiversity. For the purpose of monitoring, a number of active and passive techniques were employed. Habitat preferences for the expected species were divided into five types, namely endorheic, lacustrine, palustrine, riverine and terrestrial. Endorheic habitats were found to harbour the highest diversity (70%) of frog species. A permanent song meter was used to passively record calling activity of frog species associated with endorheic systems. This call data indicated peak breeding season, preferred calling times and intensities of the different species. Historical records from the same area were used as a basis to which this study’s data were compared. In the case of the polychromatic Argus Reed Frog Hyperolius argus Peters, 1854, questions were raised concerning the major colour changes during development of the apparent sub-­‐adult to adult life stages, an observation which was has caused some confusion as to whether these forms represented a single species or multiple cryptic species. These issues were clarified using techniques such as DNA extraction and polymerase chain reaction (PCR). Furthermore, a blood parasite survey was conducted. Thin blood smears for morphometrics and whole blood for molecular work, were collected from 29 species and 436 individual frogs. For the majority of the recorded parasites, techniques such as light microscopy were utilized for the morphological description and classification of these parasites. Among the recorded frog blood parasites observed, 20% of the frog specimens were infected with at least one blood parasite group. Hepatozoon and Trypanosoma species accounted for most of the infections; the former demonstrated significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Methods, such as transmission electron microscopy, examining the ultrastructure, as well as parasite DNA extraction and 18S rDNA gene sequences for the molecular and phylogenetic characterization, were reserved for Hepatozoon species infecting common toad species (Amietophrynus). Parasite stages observed were measured and compared to each other, as well as to other described African bufonid haemogregarines. Resulting sequences were compared with each other and to comparative haemogregarine sequences selected from GenBank. In the current study a number of important aspects with regards to monitoring and assessment of amphibians in their natural environment were explored, including looking at and determining diversity and prevalence of blood parasites. Furthermore, important data on gaining a better understanding of amphibians and their behavioural activities were also gathered, which should be able to assist in conservation actions to effectively protect South African anurans and their required habitat types. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
2

Species diversity, habitat utilization and blood parasites of amphibians in and around Ndumo Game Reserve / Edward Charles Netherlands

Netherlands, Edward Charles January 2014 (has links)
Ndumo Game Reserve is the only officially protected area within the Phongolo Floodplain; an area in the northern parts of KwaZulu-­‐Natal known to boast a rich diversity of amphibians, thus becoming one of the focal areas for this study. The study’s aim was to monitor and record amphibian diversity, as well as associated blood parasite biodiversity. For the purpose of monitoring, a number of active and passive techniques were employed. Habitat preferences for the expected species were divided into five types, namely endorheic, lacustrine, palustrine, riverine and terrestrial. Endorheic habitats were found to harbour the highest diversity (70%) of frog species. A permanent song meter was used to passively record calling activity of frog species associated with endorheic systems. This call data indicated peak breeding season, preferred calling times and intensities of the different species. Historical records from the same area were used as a basis to which this study’s data were compared. In the case of the polychromatic Argus Reed Frog Hyperolius argus Peters, 1854, questions were raised concerning the major colour changes during development of the apparent sub-­‐adult to adult life stages, an observation which was has caused some confusion as to whether these forms represented a single species or multiple cryptic species. These issues were clarified using techniques such as DNA extraction and polymerase chain reaction (PCR). Furthermore, a blood parasite survey was conducted. Thin blood smears for morphometrics and whole blood for molecular work, were collected from 29 species and 436 individual frogs. For the majority of the recorded parasites, techniques such as light microscopy were utilized for the morphological description and classification of these parasites. Among the recorded frog blood parasites observed, 20% of the frog specimens were infected with at least one blood parasite group. Hepatozoon and Trypanosoma species accounted for most of the infections; the former demonstrated significant differences in intensity of infection across species, families and habitat types (P = 0.028; P = 0.006; P = 0.007 respectively). Methods, such as transmission electron microscopy, examining the ultrastructure, as well as parasite DNA extraction and 18S rDNA gene sequences for the molecular and phylogenetic characterization, were reserved for Hepatozoon species infecting common toad species (Amietophrynus). Parasite stages observed were measured and compared to each other, as well as to other described African bufonid haemogregarines. Resulting sequences were compared with each other and to comparative haemogregarine sequences selected from GenBank. In the current study a number of important aspects with regards to monitoring and assessment of amphibians in their natural environment were explored, including looking at and determining diversity and prevalence of blood parasites. Furthermore, important data on gaining a better understanding of amphibians and their behavioural activities were also gathered, which should be able to assist in conservation actions to effectively protect South African anurans and their required habitat types. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
3

A Comparison of Current Anuran Monitoring Methods with Emphasis on the Accuracy of Automatic Vocalization Detection Software

Eldridge, Jacob Douglas 01 December 2011 (has links)
Currently, a variety of methods are available to monitor anurans, and little standardization of methods exists. New methods to monitor anurans have become available over the past twenty years, including PVC pipe arrays used for tree frog capture and Automated Digital Recording Systems (ADRS) used to remotely monitor calling activity. In addition to ADRS, machine-learning computer software, automated vocalization recognition software (AVRS), has been developed to automatically detect vocalizations within digital sound recordings. The use of a combination of ADRS and AVRS shows the promise to reduce the number of people, time, and resources needed for an effective call survey program. However, little research exists that uses the described tools for wildlife monitoring, especially for anuran monitoring. In the study, there were two problems addressed relating to AVRS. The first was the poorly understood relationship between auditory survey methods and physical survey methods. I tested this problem by using current auditory monitoring methods, ADRS and the AVRS Song Scope© (v.3.1), alongside more traditional physical monitoring methods that included drift fences, a PVC pipe array, and visual encounter transects. No significant relationship between physical and auditory community population measures was found. Auditory methods were also effective in the detection of call characteristic differences between urban and rural locations, further suggesting an influence of noise pollution. The second problem addressed was the call identification errors found in auditory survey methods. I examined the influence of treatments including the ADRS location, listener group, species, and season on the error rates of the AVRS Song Scope© (v.3.1) and groups of human listeners. Computer error rates were higher than human listeners, yet less affected by the treatments. Both studies suggested that AVRS was a viable method to monitor anuran populations, but the choice of methods should be dependent upon the species of interest and the objectives of the study.

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