Thesis (Ph. D.)--Carleton University, 1993. / Also available in electronic format on the Internet.

Anurans rely mainly on vocalizations for mate attraction while urodeles rely mainly on pheromones. However, the presence of breeding glands suggests that anurans may also communicate with pheromones during reproduction. Previous studies have shown that male Hymenochirus sp. are able to attract females in a Y-maze, most likely through chemical means, but the source of the attractant has not been identified. By exposing female Hymenochirus sp. to choice tests in a Y -maze it was demonstrated that the breeding glands of male Hymenochirus sp. are the source of a mate-attractant pheromone. This study represents the first experimental evidence for a pheromonal function of breeding glands and further supports the idea that anurans utilize pheromones in reproduction. Evidence is also presented suggesting that the mate attraction is temperature sensitive with an upper limit around 30°C.

Call number: LD2668 .T4 1949 G81 / Master of Science

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A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015. / Land transformation and associated habitat loss has been identified as one of the biggest global factors affecting decreases in frog biodiversity. Gauteng Province is South Africa’s economic hub and much of the Highveld grassland, characteristic of the region, has been transformed for urban and agricultural purposes. Large, isolated depressions underlain by impervious soils – known as pans – are typical wetland systems of the Highveld region which form habitat for many frog species. I undertook a coarse assessment of amphibian habitat in eleven pans (six representing urban and five representing agricultural areas) by measuring water quality at one point in time (electro-conductivity, temperature, pH, and concentration of sulphates, ortho-phosphates, ammonia, nitrates + nitrites and metals (Na, Mg, K, Ca)), and pan metrics, such as distance to tarred road, area of available terrestrial habitat and pan area. A frog survey using the pitfall-trap method of capture was also conducted at each of the sample sites for the purposes of evaluating frog biodiversity and spatial habitat utilisation. Evidence of acid mine drainage contamination, extensive dumping of household and building waste, nutrient enrichment and close proximity to roads with heavy traffic were found at urban sites. Agricultural sites were located significantly further away from tarred roads compared to urban sites but some were affected by deposition of eroded material from nearby cropland. A Pearson’s Correlation found a strong correlation between NO2 + NO3-N concentration and Amietophrynus gutturalis abundance across sites. Correlation matrices detected a strong, positive correlation between available terrestrial habitat adjacent to pans and pan proximity to tarred road with abundance of Cacosternum boettgeri, Pyxicephalus adspersus and Tomopterna cryptotis. At least six of the eight recorded frog species were captured at 80 m from the pan shoreline. Based on potential sensitivity of some species to available terrestrial habitat area, I recommend that buffer zones around pans should be between 100 and 500 m to ensure species persistence.