Thesis (Ph.D.)--University of Western Australia, 2005.

The Sungazer (Smaug giganteus) is an endemic lizard species that is threatened by habitat destruction and illegal harvesting, and as a result, is listed as ‘Vulnerable’ on the IUCN Red Data List. The species is restricted to the Highveld grasslands of South Africa, where over 40% of the area is used for crop monoculture, and much of the remainder has been transformed for human habitation and the construction of roads, dams, mines and power plants. This poses serious threats to the persistence of the species, as the Sungazer is a habitat specialist, and is strongly associated with pristine Themeda grassland. In addition, the species is illegally harvested from the wild for the traditional medicine, and pet trades. The rate at which these threats are removing habitat and affecting Sungazer populations is unknown, and the lack of such knowledge impedes effective conservation planning. This has prompted the call for research on the population ecology and life history of the species, so that the species can be managed. Area of occupancy. A minimum convex hull was created around all QDGCs containing species occurrence records, and an Extent of Occurrence (EOO) of 5 833 800 ha was calculated. The distribution of the species (area of QDGCs and portions of QDGCs containing occurrence records that fall within Free State and Mpumalanga Provinces) was calculated as 3 819 600 ha. Of this area, 2 053 035 ha is currently natural. To assess the proportion of EOO and distribution actually occupied by Sungazers, I surveyed 120 random sites for Sungazer presence, and found 5 containing Sungazers (4.17%) within the EOO, and 4 (5.05%) within the distribution. This measure was used to calculate the Area of Occupancy (AOO), which was 103 678 ha. Population size. I recorded a mean burrow density (MBD) of 6.14 ± 0.87 burrows/ha for 80 sites across the distribution of the species. To estimate the number of burrows within the distribution, I multiplied the MBD by the AOO. I calculated 636 325 ± 90 282 burrows. Burrow occupancy data reported in the literature indicates that only 85.7% of burrows are occupied at a given time, and there is an average occupancy of 1.83 lizards/burrow in these burrows. When applied to the number of burrows calculated, a total figure of 998 247 ± 141 632 lizards is estimated to occupy a total of 545 490 ± 77 395 burrows. Population demographics data reported in the literature indicates that 61.2% of a population is made up of mature (sexually reproductive) individuals, and when applied to the total population size, total mature individual count is 610 927 ± 86 679 Sungazers. Population decline. I visited 39 sites where Sungazer populations were reported in 1978, and found a population decline of 20.51% at these sites (0.59% decline/year). I assessed the change in land cover between 2001 and 2009 using geographic information systems (GIS) techniques and found a 13.3% decline in natural habitat across the distribution of the species over this time (1.48% decline/year). The loss of natural habitat was due primarily to an increase in cultivated areas. Priority conservation areas. Five priority zones, representing the top 20% of optimal Sungazer habitat were identified using an ecological niche model. These zones are spread across the distribution, with sites situated in the west (Welkom), north centre (Vrede, Edenville), south east (Harrismith) and north east (Volksrust). In total, the priority zones cover 1.7% of the AOO, but are estimated to contain 3-4.4% of the total population based on the habitat quality. The population size estimated contained within these zones is four to five times the mean minimum viable population (MVP) estimated for vertebrate species. Conclusion. I used my demographic measures to assess the conservation status of S. giganteus using Version 3.1. of the IUCN Categories and Criteria for conservation assessments. This assessment improves the precision of the measure of population reduction and includes geographic range for the species. My conservation assessment confirms the current listing of S. giganteus as ‘Vulnerable’ under criteria A2bcd and B2ab. I highlight the need for developing a protocol for translocations, a phylogeographic study to assess the landscape genetics of the species, an investigation of dispersal patterns and colonisation strategies.

Within-island geographic variation in three character systems (body dimensions, scalation, colour pattern) and in life history is described in the Gran Canarian skink (Chalcides sexlineatus). Numerical methods used to describe patterns of geographic variation include contouring, principal components analysis, multiple group principal components analysis and canonical variates analysis. The primary patterns of geographic variation are north-east/south-west clines, although altitudinal variation is also evident in some characters. Several hypothesized causes of the variation are erected and tested using Mantel Tests and partial correlation. This points to lush/arid ecotone adaptation as the cause. A suggestion by previous workers that there are two species on the island is rejected. Patterns of geographic variation in Chalcides viridanus on the neighbouring island of Tenerife are described and tested against hypotheses using similar methods. Tenerife shows similar lush/arid variation to that in Gran Canaria. Parallel patterns of geographic variation in morphology are found, most notably in colour pattern. This strongly suggests that adaptation to current ecological conditions, rather than ancient population vicariance, is the cause. Geographic variation in anti-predator strategy can explain the colour pattern microevolution. Ecological differences between populations of C. sexlineatus are investigated to elucidate the actual selection pressures acting on different aspects of the animals' morphology. Some thermoregulatory and also dietary and prey size differences are found among populations. Daily energy expenditure and water flux are compared among skinks from northern and southern populations in the field, using the doubly-labelled water technique. Between-population differences in energy expenditure can be attributed to body size differences.

No description available.

x, 149 leaves : ill., maps ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Genetics, 1976

Thesis (Ph.D. 1973) from the dept. of Zoology, University of Adelaide.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 311-319). Available also in a digital version from Dissertation Abstracts.

Inaug.-diss.-Bonn. / Lebenslauf. "Literaturverzeichnis": p. 30-31.

No description available.

The animal kingdom contains a spectacular diversity in colour signals used to indicate quality. The challenge of understanding this diversity lies in identifying and interpreting constraints on signals that maintain signal honesty. I used an integrative approach to measure the effects of potential signal modulators on whole-animal performance, ornaments, condition and immunocompetence in the lizard P. i. wilhelmi. This approach attempts to remove some of the uncertainty surrounding the validity of existing handicap models. First, I investigated seasonal changes in testosterone, corticosterone and carotenoids and compared these to seasonal changes in endurance, immunocompetence and body condition male P. i. wilhelmi. I also determined which colour patches were predictors of male quality by relating them to morphology, endurance, body condition and immunocompetence. I found some support for the immunocompetence handicap hypothesis so I tested whether testosterone was modulating ornaments and constraining signals through its immunosuppressive properties. I tested the immunocompetencehandicap hypothesis in male P. i. wilhelmi while also conducting parallel studies with free-ranging and captive-housed lizards to assess whether there were differences between the groups that could indicate exogenous factors influencing signalling in their natural environment. While experimentally elevated testosterone did affect endurance and the properties of their colour patches, immunosuppression was only evident in free-ranging lizards. To measure the extent of organisational effects in males I also manipulated testosterone in females and found no evidence of immunosuppression although testosterone did affect some aspects of colouration and endurance. Next, I tested the stress-linked immunocompetence handicap hypothesis by experimentally elevating testosterone, corticosterone, or both at the same time. I found that corticosterone had an isolated effect on one colour patch, and testosterone and corticosterone had opposing effects on endurance that were negated when both were elevated. Different colour patches were affected by either testosterone or corticosterone with little overlap, and the combination of the two had a different action to either hormone elevated in isolation. Finally, I tested the oxidative stress hypothesis of carotenoids as a limiter of signal output due to their requirement in the oxidative stress response. I found that supplemented carotenoids vastly improved endurance, immune response and influenced different aspects of colouration to that of testosterone and corticosterone. My study examined four different hypotheses of constraints on signalling involving testosterone, corticosterone, interactions between testosterone and corticosterone and carotenoids in a consistent manner measuring multiple indices of quality as well as multiple colour signals. This study provides a unique integrative perspective on the roles played by each factor as well as prompting us to re-examine our approach to understanding constraints on signalling.