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.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: An understanding of the phylogeography and evolutionary processes involved in speciation is essential for the conservation and management of any particular species. To investigate the phylogeographic patterns in Agama atra from the Cape Fold Mountains (CFM), 98 individuals from 38 geographically close localities were analysed. In addition, to understand the phylogeographic associations between the CFM populations and the rest of Southern Africa, 18 specimens from 12 localities outside the CFM were also included. A total of 988 characters derived from two mitochondrial DNA fragments (control region and ND2) revealed 59 distinct haplotypes in the CFM. Parsimony, Bayesian and maximum likelihood analyses revealed four distinct clades associated with geography within the CFM. These clades were supported by a haplotype network and were defined as the Cape Peninsula clade, the Limietberg clade, the northern CFM clade and the central CFM clade. Analysis of molecular variance confirmed the high degree of genetic structure within the CFM, with more than 75% of genetic variation found among the geographic areas. SAMOVA and nested clade analysis (NCA) suggest that the central CFM clade may be more diverse than detected by the networks and the phylogenetic analyses. The processes that caused the four distinct genetic groups in the CFM are not yet clear. Using a speculative molecular clock estimate, the main cladogenesis of A. atra within the CFM took place, approximately ~6.5 - 9 MYA. This dating coincides well with the documented Miocene-Pliocene climate fluctuations which might have contributed towards the isolation among lineages. The genetic structure found in A. atra is also markedly congruent with what has been found in other taxa such as Mesamphisopus spesies, Potamonautes brincki, and Pedioplanis burchelli and this would further support vicariance as a main isolating factor here. / AFRIKAANSE OPSOMMING: ‘n Goeie begrip van die filogeografie en die evolusionêre gebeurtenisse wat verband hou met spesiasie is belangrik vir die bewaring en bestuur van enige spesie. Om die filogeografiese patrone in Agama atra van die Kaapse Plooiberge (KPB) te ontleed, was 98 individue van 38 nabygeleë lokaliteite geanaliseer. Tesame met bogenoemde monsters was 18 individue van 12 lokaliteite van buite die KPB ook geanaliseer om die filogeografiese verwantskappe tussen die KPB bevolkings en die res van Suidelike Afrika te ondersoek. Uit ‘n totaal van 988 karakters verkry uit twee mitochondriale DNS fragmente (die kontrole gebied en ND2) is 59 haplotipes gevind. Parsimonie en modelgebaseerde filogenetiese analises dui daarop dat vier groepe geassosieer met geografie binne die KPB voorkom. Die groepe word geondersteun deur ‘n haplotipe netwerk en word soos volg gedefinieer: ‘n Kaapse Peninsula groep, ‘n Limietberg groep, ‘n noordelike KPB groep en ‘n sentrale KPB groep. Analises van molekulêre variansie (AMOVA) bevestig die hoë graad van genetiese struktuur binne die KPB, met meer as 75% genetiese variasie gevind tussen die geografiese areas. SAMOVA en gesetelde groep analises (“NCA”) stel voor dat die sentrale KPB groep dalk meer variasie vertoon as wat die netwerk en filogenetiese analises vertoon. Die prosesse wat die vier genetiese groepe tot stand gebring het is nog nie bekend nie. Volgens ‘n spekulatiewe molekulêre klok berekening het die hoof kladogenese van A. atra binne die KPB ongeveer ~6.5 - 9 miljoen jaar (MJ) gelede plaasgevind. Hierdie datering stem goed ooreen met die gedokumenteerde Mioseen-Plioseen klimaat veranderinge wat isolasie van die groepe kon bewerkstellig het. Die genetiese struktuur van A. atra in the KPB is ook gevind in ander taksa soos Mesamphisopus spesies, Potamonautes brincki, en Pedioplanis burchelli en bevestig dus dat vikariansie hier die hoof faktor vir isolasie is.

Dissertation (PhD)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The taxonomic status of southern Africa’s rupicolous crag lizards (genus Pseudocordylus) was investigated. As considerable confusion exists in the literature regarding the type specimens and type localities of the various taxa, resolution of these problems were considered the starting point of the study. Examination of museum specimens allowed for the designation of lectotypes, alloparalectotypes and/or paralectotypes. Of particular relevance to this study was the rediscovery of Andrew Smith’s type specimens of P. m. melanotus and P. m. subviridis. Restriction of the type locality of P. m. subviridis, based on entries in Smith’s diary and journal, allowed for the confirmation of previous interpretations and definitions of the two taxa. The geographical distribution of the various taxa and populations was determined using an extensive locality database. Two kinds of molecular markers, namely allozymes and mitochondrial DNA, were used in an attempt to resolve taxon boundaries within the P. melanotus species complex. The allozyme analysis indicated that P. m. melanotus might be polyphyletic and comprised of two unrelated lineages. Furthermore, fixed allelic differences between parapatric populations of P. m. melanotus and P. m. subviridis, and between sympatric populations of P. m. subviridis and P. langi, suggested that all three forms might be considered full species, with the possibility of more cryptic species present in the complex. Pseudocordylus transvaalensis differed from most other populations by 1-3 fixed allelic differences, but was indistinguishable from the Nkandhla district (central KwaZulu-Natal) population of P. m. melanotus. There were no heterozygous individuals in a sample from Monontsha Pass (Qwa-Qwa), a population reportedly comprising P. m. melanotus and P. m. subviridis, as well as intermediates, and all specimens were assignable to P. m. subviridis. The allozyme study was, however, based on phenetic principles and for further taxonomic resolution a cladistic approach was required. An mtDNA analysis (16S rRNA gene) using Maximum Parsimony, Maximum Likelihood and Bayesian analyses was therefore conducted to determine phylogenetic relationships among species and subspecies and to re-assess the taxonomic status of forms in the P. melanotus species complex. The mtDNA analysis corroborated most of the results obtained in the allozyme analysis. Firstly, P. langi was again found to be basal. With the addition of P. microlepidotus and P. spinosus to the ingroup, it is now apparent that P. langi is the basal species in the genus. (Recent studies have indicated that P. capensis and P. nebulosus are not congeneric with Pseudocordylus.) Secondly, the 16S rRNA results confirm that P. m. melanotus, as presently construed, is comprised of two clades that are not sister groups. The northern populations of P. m. melanotus (Sabie and Lochiel) form a fairly deeply divergent clade that may represent a separate species. The Nkandla population was, however, found to cluster with the other southern P. m. melanotus populations and not with P. transvaalensis as was the case in the allozyme electrophoretic analysis. However, the most surprising result of the 16S rRNA analysis was the finding that both P. microlepidotus and P. spinosus are embedded within P. m. subviridis. This suggests that these two species evolved from within P. m. subviridis and may have been separated only recently, with rapid morphological divergence occurring, but with limited genetic differentiation. It is suggested that all of the above three taxa be provisionally treated as full species. There was also morphological support for the uniqueness of all groupings indicated by the mtDNA analysis. Pseudocordylus transvaalensis is characterized by its large size, unique dorsal and gular (black) colour patterns, as many as three horizontal rows of lateral temporal scales, a series of small scales posterior to the interparietal scale, and usually two subocular scales behind the median subocular on either side of the head. The various populations currently classified under the name P. melanotus are more difficult to separate, but P. m. melanotus and P. m. subviridis usually differ as follows: frontonasal divided in P. m. melanotus, undivided in P. m. subviridis (and most Northern melanotus); lateral temporals in two rows, upper more elongate versus single row of much elongated scales; longitudinal rows of dorsolaterals closely-set versus widely separated; femoral pores of females pit-like versus deep with secretory plug. Northern melanotus differs from Southern melanotus in usually having an undivided frontonasal scale and seldom having a small scale present behind the frontonasal. Pseudocordylus langi has unique dorsal and gular colour patterns (including a series of blue spots on the flanks), granular dorsals with 6-9 paravertebral rows of enlarged flat scales, high total numbers of femoral pores (25-34) and usually only five (smooth not keeled or ridged) infralabial scales on either side of the head. Pseudocordylus spinosus also has unique dorsal and gular colour patterns, spinose lateral scales, frontonasal longer than wide and excluded from the loreal scales, low total femoral pore counts (6-9), and females (not only males) have differentiated femoral scales. Both Principal Components Analysis (PCA) and Canonical Discriminant Analysis (CDA) distinguished four groups, namely P. transvaalensis, P. langi, P. spinosus and a P. melanotus/subviridis/microlepidotus cluster. A separate CDA of all P. melanotus populations partly distinguished between Southern melanotus and P. m. subviridis, and largely separated Northern melanotus; whereas a CDA of P. transvaalensis showed that all three allopatric populations are 100% distinguishable in morphological space. A Nested Clade Analysis indicated that fragmentation as well as range expansion played a role in the distribution of the P. melanotus species complex. This may be explained by climatic oscillations (high-low temperatures and wet-dry cycles) during the Cenozoic that caused habitat expansion and contraction. Based on the topology of the mtDNA phylogram it is apparent that the genus Pseudocordylus originated along the eastern escarpment. A P. langi-like ancestor may have had an extensive range along the eastern escarpment, with the Maloti-Drakensberg forming the southern limit of its range. During a subsequent rise in global temperatures, range contraction and fragmentation took place, leaving an isolated population in the south and one in the north. The southern population survived unchanged in the Maloti-Drakensberg refugium, but the northern population was forced to adapt to the warmer conditions. Thereafter, the northern form expanded its range again, but during a subsequent cooler period, range contraction occurred, resulting in an isolated north-eastern population in the Sabie-Lochiel area in Mpumulanga (Northern melanotus) and a western population. Relationships in the latter clade are not sufficiently resolved to allow further reconstruction of biogeographic history, but it is clear that a P. m. subviridis-like form became isolated in the south where it eventually came into contact with P. langi at high elevations. Pseudocordylus m. subviridis eventually extended its range southwestwards into the inland mountains of the Eastern Cape and Cape Fold Mountains to give rise to the P. microlepidotus complex. This cycle of range expansion and contraction may also account for the isolated populations at Suikerbosrand, Nkandhla district, and in the Amatole-Great Winterberg mountain region. Furthermore, it is suggested that P. spinosus originated from a P. m. subviridis-like ancestral population that became isolated on the lower slopes of the Drakensberg where terrestrial predation pressure resulted in a quick shift in morphology from fairly smooth body scales to a more spiny morphology. / AFRIKAANSE OPSOMMING: Die taksonomiese status van suidelike Afrika se rotsbewonende krans-akkedisse (genus Pseudocordylus) is ondersoek. Omdat daar aansienlike verwarring in die literatuur bestaan met betrekking tot die tipe monsters en die tipe lokaliteite van die verskillende taksa, is die oplossing van hierdie probleme as die beginpunt van hierdie studie geneem. Die bestudering van akkedismonsters in museums het dit moontlik gemaak om lektotipes, alloparalektotipes en/of paralektotipes aan te wys. Van besondere belang vir hierdie studie is die herontdekking van Andrew Smith se tipe monsters van P. m. melanotus en P. m. subviridis. Die beperking van die tipe lokaliteit van P. m. subviridis, gebaseer op inskrywings in Smith se dagboek en joernaal, het dit moontlik gemaak om vorige interpretasies en definisies van die twee taksa te bevestig. Die geografiese verspreiding van die verskillende taksa en bevolkings is bepaal deur middel van ’n omvattende lokaliteit databasis. Twee soorte molekulêre merkers, naamlik allosieme en mitokondriale DNS, is gebruik in ʼn poging om uitsluitsel te verkry oor die takson-grense binne die P. melanotus-spesiekompleks. Die allosiem-analise het daarop gedui dat P. m. melanotus moontlik polifileties mag wees en uit twee onverwante stamboom-vertakkings kan bestaan. Verder het vaste alleliese verskille tussen parapatriese bevolkings van P. m. melanotus en P. m. subviridis, en tussen simpatriese bevolkings van P. m. subviridis en P. langi, daarop gedui dat al drie vorme as volledige spesies beskou kan word, met die moontlikheid dat meer kriptiese spesies in die kompleks teenwoordig kan wees. Pseudocordylus transvaalensis het van die meeste ander bevolkings verskil met 1-3 vaste alleliese verskille, maar was ononderskeibaar van die bevolking van P. m. melanotus van die Nkandhla distrik (sentraal KwaZulu-Natal). Daar was slegs homosigote individue in ʼn steekproef van Monontsha Pas (Qwa-Qwa), ʼn bevolking wat volgens die literatuur P. m. melanotus en P. m. subviridis, sowel as intermediêre omvat, en alle monsters was toekenbaar aan P. m. subviridis. Die allosiemstudie is egter gebaseer op fenetiese beginsels en vir verdere taksonomiese oplossing is ʼn kladistiese benadering vereis. ʼn Mitokondriale DNS-analise (16S rRNS geen) wat gebruik maak van Maksimum Parsimonie-, Maksimum Waarskynlikheids- en Bayes-analises is daarom uitgevoer om die filogenetiese verwantskappe tussen spesies en subspesies te bepaal en om die taksonomiese status van vorme in die P. melanotus-spesiekompleks te herondersoek. Die mtDNS-analise het die meeste van die resultate van die allosiem-analise bevestig. Eerstens, P. langi is weer bevind om basaal te wees. Met die byvoeging van P. microlepidotus en P. spinosus tot die binne-groep het dit nou duidelik geword dat P. langi die basale spesie in die genus is. (Onlangse studies het aangedui dat P. capensis en P. nebulosus nie kongeneries met Pseudocordylus is nie.) Tweedens, die 16S rRNS resultate bevestig dat P. m. melanotus, soos tans vasgestel, saamgestel is uit twee klade wat nie sustergroepe is nie. Die noordelike bevolkings van P. m. melanotus (Sabie en Lochiel) vorm ʼn redelik diep divergente klaad wat ʼn afsonderlike spesie mag verteenwoordig. Dit is egter bevind dat die Nkandla bevolking saamgegroepeer het met die ander suidelike P. m. melanotus-bevolkings en nie met P. transvaalensis soos wat die geval was in die allosiem-elektroforetiese analise nie. Die mees verbasende resultaat van die 16S rRNS-analise was egter die bevinding dat beide P. microlepidotus en P. spinosus genestel was binne P. m. subviridis. Dit dui daarop dat hierdie twee spesies kon ontwikkel het vanuit P. m. subviridis en slegs onlangs van mekaar geskei het, toe vinnige morfologiese splitsing voorgekom het, maar met beperkte genetiese differensiasie. Dit word voorgestel dat al drie die bogenoemde taksa voorlopig as volledige spesies beskou word. Daar was ook morfologiese steun vir die uniekheid van al die groeperings wat die mtDNS-analise uitgewys het. Pseudocordylus transvaalensis kan uitgeken word aan sy bogemiddelde grootte, unieke dorsale en (swart) kleurpatrone op die keel, so veel as drie horisontale rye lateraaltemporale skubbe, ʼn reeks klein skubbe agter die interpariëtale skub, en gewoonlik twee subokulêre skubbe agter die middelste subokulêre skub op beide kante van die kop. Die verskillende bevolkings wat tans geklassifiseer word as P. melanotus is moeiliker om van mekaar te skei, maar P. m. melanotus en P. m. subviridis verskil gewoonlik soos volg: frontonasale skub in twee gedeel in P. m. melanotus, heel in P. m. subviridis (en in die meeste Noordelike melanotus); lateraal-temporale skubbe in twee rye, die boonste ry met verlengde skubbe teenoor ʼn enkele ry verlengde skubbe; longitudinale rye van dorsolaterale skubbe naby aan mekaar teenoor ver uit mekaar; femorale porieë van wyfies klein en vlak teenoor diep met sekreterende proppe. Noordelike melanotus verskil van Suidelike melanotus deurdat hulle gewoonlik ʼn heel frontonasale skub het en daar selde ʼn klein skub teenwoordig is agter die frontonasale skub. Pseudocordylus langi het unieke dorsale en keel-kleurpatrone (wat ʼn reeks blou kolle op die sye insluit), granulêre dorsale skubbe met 6-9 rye vergrote plat skubbe langs die rugsteen, ʼn groot totale aantal femorale porieë (25-34), en gewoonlik net vyf (glad, ongerif) infralabiale skubbe op elke kant van die kop. Pseudocordylus spinosus het ook unieke dorsale en keel-kleurpatrone, skerp laterale skubbe, frontonasale skub langer as wyd en nie in kontak met die loreale skubbe nie, klein totale aantal femorale porieë (6-9), en wyfies (nie net mannetjies nie) het gedifferensieerde femorale skubbe. Die Hoof-komponent Analise (HKA) en die Kanonieke Diskriminant Analise (KDA) het albei vier groepe geïdentifiseer, naamlik P. transvaalensis, P. langi, P. spinosus en ʼn P. melanotus/subviridis/microlepidotus groepering. ʼn Aparte KDA van alle P. melanotus bevolkings het gedeeltelik onderskei tussen Suidelike melanotus en P. m. subviridis, en die Noordelike melanotus is grootliks van die ander onderskei; terwyl ʼn KDA van P. transvaalensis daarop gedui het dat al drie allopatriese bevolkings 100% onderskeibaar in morfologiese ruimte is. ʼn Genestelde Klaad-Analise het aangedui dat fragmentasie, sowel as gebiedsuitbreiding, ʼn rol gespeel het in die verspreiding van die P. melanotus-spesiekompleks. Dit kan moontlik verklaar word deur die klimaatswisselinge (hoë-lae temperature en nat-droë siklusse) gedurende die Senosoikum wat habitat-uitbreiding en –verkleining veroorsaak het. Gebaseer op die topologie van die mtDNS filogram is dit duidelik dat die genus Pseudocordylus al langs die oostelike platorand ontstaan het. ʼn Voorouer soortgelyk aan P. langi kon ʼn uitgebreide gebied al langs die oostelike platorand gehad het, met die Maloti-Drakensberg wat die suidelike limiet van hierdie gebied gevorm het. Gedurende ʼn daaropvolgende toename in globale temperature het gebiedsverkleining en fragmentasie plaasgevind, wat ʼn geïsoleerde bevolking in die suide en een in die noorde tot gevolg gehad het. Die suidelike bevolking het onveranderd oorleef in die Maloti-Drakensberg skuilplek (“refugium”), maar die noordelike bevolking is geforseer om aan te pas in die warmer toestande. Daarna het die noordelike vorm se gebied weer uitgebrei, maar gedurende ʼn daaropvolgende koeler periode het gebiedsverkleining weer plaasgevind, met die gevolg dat daar ʼn geïsoleerde noord-oostelike bevolking in die Sabie-Lochiel-area in Mpumalanga (Noordelike melanotus) en ʼn bevolking in die weste was. Verwantskappe in die laasgenoemde klaad is nie voldoende opgelos om verdere rekonstruksie van die biogeografiese geskiedenis moontlik te maak nie, maar dit is duidelik dat ʼn vorm soortgelyk aan P. m. subviridis geïsoleer geraak het in die suide waar dit eindelik op hoë liggings in kontak gekom het met P. langi. Die gebied van P. m. subviridis is ook later suidweswaarts uitgebrei tot in die binnelandse berge van die Oos-Kaap en Kaapse Plooiberge om tot die ontstaan van die P. microlepidotuskompleks aanleiding te gee. Hierdie siklus van gebiedsuitbreiding en verkleining kan ook ʼn verklaring bied vir die geïsoleerde bevolkings by Suikerbosrand, Nkandhla distrik, en in die Amatole-Groot Winterberg-streek. Verder word voorgestel dat P. spinosus ontstaan het uit ʼn voorouerlike bevolking soortgelyk aan P. m. subviridis wat geïsoleerd geraak het op die laer hange van die Drakensberg waar die druk van aardsbewonende roofdiere tot ʼn vinnige verandering in morfologie vanaf redelik gladde liggaamskubbe tot ʼn meer skerppuntige morfologie gelei het.

Thesis (MSc)--Stellenbosch University, 1998 / Stellenbosch University. Faculty of Science. Dept. of Botany & Zoology. / ENGLISH ABSTRACT: There has been a long-standing need to systematically analyze and classify South African fossil Lacertilia. Although extensive assemblages of fossil lizard and amphibian material from Langebaan on the West Coast and elsewhere exist in museum collections, the fragmentary nature of the material has largely prevented in-depth analyses and identification. In this comparative study the skulls and lower jaws of 7 lizard genera, representing the six extant South African families, were disassembled and the bones analyzed individually. The aim was to compile a comparative database of each bone against which current and future fossil finds could be matched. Detailed descriptions of the isolated elements were given. The results showed that despite some intra-generic variation, unique structural differences do exist in individual bones which may be utilized in the taxonomic assessment of fragmentary fossil material. / AFRIKAANSE OPSOMMING: Daar bestaan lank reeds 'n behoefte vir die sistematiese analise en klassifisering van fossielmateriaal van Suid-Afrikaanse Lacertilia. Alhoewel uitgebreide versamelings van akkedis- en amfibier-fossiele van Langebaan aan die Weskus en elders in museums bestaan, het die fragmentariese aard van die materiaal grootliks diepgaande analises en identifikasie belemmer In hierdie vergelykende studie is die skedels en onderkake van 7 akkedisgenera, wat die ses resente Suid-Afrikaanse families verteenwoordig, gedisartikuleer en elke been individueel geanaliseer. Die doel was om 'n vergelykende databasis van elke been saam te stel waarmee huidige en toekomstige fossielvondse vergelyk kan word. Gedetaileerde beskrywings van die ge'isoleerde elemente word gegee. Die resultate toon dat desondanks 'n mate van intra-generiese variasie, unieke strukturele verskille tussen individuele bene weI bestaan en dat hierdie verskille gebruik kan word om fossielfragmente taksonomies te analiseer.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 1990. / Mouton and Oelofsen (1988) suggested that melanistic cordylid populations in the southwestern Cape represent relict, cold-adapted populations which evolved under adverse climatic conditions during the Last Glacial Period, 18000-16000 BP. The first section of this study was undertaken to test their model for the evolution of melanism in the cordylid species, Cordylus polyzonus. For this purpose, geographic character variation among populations of Cordylus polyzonus in the region south of 32°15' latitude and west of 19015' longitude was investigated. Variation in 122 external morphological characters was analysed in 306 specimens from 93 localities. Although no inter-locality variation was observed in most of the characters, a high degree of concordancy was observed in the geographical variation of three headshield characters. These three headshield characters are considered non-adaptive and can accordingly be regarded as good indicators of genealogical relationship. Since they varied together with other adaptive characters such as melanism and body size, it can be concluded that geographically isolated melanistic populations of Cordylus polyzonus represent relicts of a once larger melanistic population. The data underscore the Mouton-Oelofsen hypothesis for the evolution of melanistic cordylid taxa in the south-western Cape. A further corrolary of the Mouton-Oelofsen hypothesis, is that melanistic cordylids are presently restricted to cool enclaves. This assumption was evaluated in the second section of this study by analysing prevailing climatic conditions associated with the occurrence of extant melanistic populations of the genera Cordylus and Pseudocordylus in the southwestern Cape. Climatic data were obtained from 123 weather stations in the study-area. A close correspondence was found between the distribution of melanistic populations along the westcoast and the primary upwelling zones of the southern Benguela Current. Lower mean daily temperatures and a high incidence of advective sea fog on the adjacent coastal regions are direct effects of these cold upwelled waters. Likewise, montane melanistic populations, occurring at relatively high altitudes along the extreme western borders of the Cape Fold Mountains, also experience lower mean daily temperatures and a high incidence of orographic fog and cloud cover. Melanistic cordylid populations therefore generally have to 4. contend with relatively exposed environmental conditions of low temperature and limited solar radiation due to the filtering effect of fog and cloud cover. The fact that all the melanistic taxa in this region occur as small isolated populations limited to cool enclaves, suggests that they are presently in a contracted state under strong environmental pressure. It is postulated that palaeoclimatic conditions very similar to climatic conditions presently prevailing in these enclaves were experienced over the entire western coastal region, at least as far as the Orange River, during the Last Glacial Maximum when melanism probably evolved. Our results therefore corroborate the Mouton-Oelofsen hypothesis that isolated melanistic cordylid populations represent cold-adapted relicts. One would accordingly expect melanistic populations to posses some enhanced ability to absorb infrared radiant heat to cope with these conditions of limited sunshine and lower temperatures. In section three of this study, differences in dorsal skin reflectivity between melanistic and turquoise ~. polyzonus populations were quantified. Furthermore, the physiological ability of this species to change body colour was investigated, as well as ontogenetic colour change. Significant differences in dorsal skin reflectivity existed between melanistic and turquoise specimens in the 500-1300 mjl spectral range, demonstrating the greater heat-absorbing capacity of melanistic populations. The data underscore the MoutonOelofsen model that melanistic populations are "cold-adapted" relicts. Furthermore, ontogenetic colour change is a real phenomenon in the melanistic variation of C. polyzonus. In this respect it is unique among the melanistic cordylid taxa in that ontogenetic colour change seemingly does not occur in the other forms. Experiments to investigate short term colour change in response to different temperatures regimes, produced no conclusive results. On the other hand, seasonal colour changes could be demonstrated for both melanistic and turquoise specimens, indicating that this species has the physiological capacity to change colour. It is, however, believed that geographic colour variation in ~. polyzonus cannot be attributed to this capacity, but is rather the result of selection over time. This view is underscored by the results of section one demonstrating that, apart from colour and body size, melanistic and turquoise forms also differ in certain non-adaptive traits; suggesting that they do not belong to the same primary gene pool.