Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Within arthropods, inter-individual and inter-population variation is generally poorly explored for physiological parameters. Such physiological variability is important, as it can provide insight into the capacity for evolutionary adaptation and how animals may cope with anthropogenic climate change. Insect vectors of human and animal diseases, such as tsetse flies (Diptera, Glossinidae) which carry trypanosomes, are of particular interest. Predictions of tsetse fly (Glossina spp.) range expansion, possibly paralleled by increased disease occurrence, have been made under future climate scenarios. Moreover, since there are generally strong relationships between abiotic variables (e.g. temperature and moisture availability), population dynamics, distribution and abundance, determining the physiological mechanisms influencing such relationships has utility for predictive modelling of spatial and temporal changes in tsetse fly distributions. I investigated physiological variation among individuals and populations, focusing mainly on Glossina spp. but using other arthropods to address certain issues. Specifically, I show the following: i) metabolic rate is repeatable (intra-class correlation coefficient) within individuals, and may be influenced by several factors such as age, gender, body mass and pregnancy; ii) while metabolic rate is repeatable within individuals, it remains unaltered with acclimation to laboratory conditions from field collection; iii) within a population, metabolic rate-temperature relationships are surprisingly invariant among physiological states such as age, gender, feeding status, pregnancy and temperature acclimation; iv) the magnitude of the effect of temperature acclimation differs among traits, in that upper thermal tolerances respond less than lower thermal tolerances, while metabolic rate responds to heat but not to cold. Water loss rate is relatively unresponsive to either treatment; v) plasticity can account for most inter-population variation in physiological traits related to climatic stress resistance (e.g. thermotolerances and desiccation rates) in the natural environment; vi) adult physiological performance responds differently to developmental and adult acclimation, such that marked traitspecific variation occurs, and combinations of both developmental and adult plasticity can result in further alteration of adult performance. These results have implications for the evolution of stress resistance to abiotic factors in these and other arthropods. I conclude by discussing the potential physiological patterns linking population dynamics and abiotic factors, with particular reference to tsetse flies. / AFRIKAANSE OPSOMMING: Binne arthropoda, is tussen-individu en tussen-bevolking variasie in die algemeen sleg bestudeer vir fisiologiese parameters. Hierdie fisiologiese variasie is belangrik want dit kan insig gee in die mate van evolusionêre aanpassing en hoe diere antropogenies klimaatsverandering kan hanteer. Dit is veral belangrik in die geval van insekte wat mens- en diersiektes kan dra, soos tsetse vlieë (Diptera, Glossinidae) wat trypanosome oordra. In die geval van tsetse vlieë (Glossina spp.) is voorspellings vir verhoogde verspreiding, en gevolglik verhoogde siekte voorkoms, gemaak onder toekomstige voorkoms klimaat senario’s. Verder, aangesien daar in die algemeen sterk verwantskappe tussen abiotiese parameters (bv. temperatuur en water beskikbaarheid), bevolkingsdynamika, verspreiding en voorkoms is, is die bepaling van die fisiologiese meganisme, wat ‘n invloed het op hierdie verwantskappe, nuttig vir die voorspelling van tsetse oor spasie en tyd. Hier, met hoofsaaklik die gebruik van Glossina spp., maar ook ander arthropoda wanneer dit nodig is, word navorsing wat fisiologiese variasie tussen individue en bevolkings aanspreel voorgelê. Spesifiek, word dit gewys dat i) metaboliese tempo is herhaalbaar (intra-klas korrelasie koeffisient) binne individue, alhowel metaboliese tempo kan beinvloed word deur faktore soos ouderdom, geslag, liggaamsmassa en swangerskap, ii) terwyl metaboliese tempo binne individue herhaalbaar is, verander dit nie met akklimasie na laboratorium toestande vanaf versameling in die veld, iii) binne ‘n bevolking metaboliese tempo-temperatuur verwantskappe is verbasend eenders tussen fisiologiese toestande soos ouderdom, geslag, voeding staat, swangerskap en temperatuur akklimasie, iv) die grootte van die effek van temperatuur akklimasie verskil tussen eienskappe, en die boonste termiese limiete reageer minder as laer termiese limiete, terwyl metaboliese tempo reageer op hitte maar nie koue nie, en waterverlies tempo is relatief terughoudend tot enige temperatuur toestand, v) buigbaarheid kan die meeste van inter-bevolkingsvariasie in fisiologiese eienskappe van klimaatstres weerstandsvermoë (termiese toleransie en uitdrogingstempo) in die natuurlike omgewing verklaar, vi) volwasse fisiologiese prestasie reageer verskillend op ontwikkelende en volwasse akklimasie, soveel dat eienskap-spesifieke variasie kan voorkom, en ‘n kombinasie van beide ontwikkelende en volwasse buigbaarheid ‘n verskillende volwasse prestasie tot gevolg kan hê. Hierdie resultate het implikasies vir die evolusie van weerstandsvermoë tot abiotiese faktore in hierdie en ander arthropoda. Hierdie tesis word afgesluit met ‘n bespreeking van die moontlikke fisiologiese patrone wat bevolkingsdinamika en abiotiese faktore kan verbind, met ‘n fokus op tsetse vlieë.

Thesis (PhD (Botany and Zoology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Although the impacts of biological invasions are widely appreciated, a bias exists in research effort to post‐dispersal processes because of the difficulties of measuring propagule pressure and the detecting of newly established species. Here the Antarctic is used as a model system in which to quantify the initial dispersal of alien species and investigate the factors that contribute to the establishment and range dynamics of alien species once they have arrived in the region. Human movements are known to transport alien species into the Antarctic, some of which have successfully established and had wide ranging consequences in recipient ecosystems. Considering terrestrial flora, this research found that over 700 seeds from 99 taxa, including some species known to be invasive, are transported into the Antarctic each year in association with South African National Antarctic Programme (SANAP) passenger luggage and cargo. The first ever assessment of propagule drop‐off indicated that 30‐50% of these propagules will enter the recipient environment. Further results suggested that the construction of the British Antarctic Survey Halley VI station will facilitate the transport of over 5000 seeds from 34 taxa into the region, making this a significant pathway for introductions. Propagule pressure due to SANAP logistics is also considerable for marine species. Fouling assemblages on the external hull surfaces of the SANAP resupply vessel, the SA Agulhas, form only once the vessel’s anti‐fouling paint has been damaged by travel through sea ice and are characterised by low diversity. Ice scour prevents fouling assemblages from being transported to the Antarctic continent, but assemblages remain largely intact when travelling to sub‐Antarctic Islands. In the sea‐chests of the vessel populations of a known invasive, Mytilus galloprovincialis, were found with some individuals having survived transportation to the Antarctic region on multiple occasions. Once species have overcome initial dispersal barriers, they face further ecological and physiological challenges in order to establish in the recipient region. The parasitoid wasp Aphidius matricariae was first recorded on Marion Island in 2001. Surveys around the island show that adult abundance and the frequency of aphid parasitism are highest adjacent to a common anchor point of the SA Agulhas and decline away from this region. Genetic diversity was low, suggesting that the population was established from a single introduction. This highlights that high propagule pressure is not necessary for successful establishment of introduced invertebrates. Another species that has overcome the dispersal barrier is the terrestrial slug Deroceras panormitanum, which was introduced to Marion Island in the 1970’s and has since spread throughout much of the coastal habitat of the island. For this species range limits are set by intolerance of low temperature and salinity, and abundance structure is characterized by patches and gaps which are associated with this species inability to tolerate dry conditions. To prevent further alien introductions in the region, targeted management of high risk pathways is required. In addition, increased vigilance is needed to detect and manage newly established aliens before their ranges expand. / AFRIKAANSE OPSOMMING: Alhoewel die impak van biologiese indringings in die breë waardeer word, bestaan daar vooroordeel in navorsingspogings ten opsigte van na‐verspreidingsprosesse, weens die moeilikhede om verspreidingseenheid druk te meet en in die opsporing van nuut gevestigde spesies. Hier word die Antarktiese streek as ‘n model sisteem gebruik waarin die aanvanklike verspreiding van uitheemse spesies gekwantifiseer kan word en om die faktore wat bydrae tot die vestiging en grens dinamika van uitheemse spesies te ondersoek, wanneer hulle in ’n streek aangekom het. Menslike bewegings is bekend daarvoor om uitheemse spesies na die Antarktiek te vervoer, sommige waarvan suksesvol gevestig het en omvattende gevolge in die ontvanger ekosisteme gehad het. Aangaande terrestriële flora het hierdie navorsing gevind dat oor die 700 sade van 99 taxa, insluitende sommige spesies wat bekend is om indringend te wees, jaarliks na die Antarktiek vervoer word in assosiasie met die Suid Afrikaanse Nasionale Antarktiese Program (SANAP) se bagasie en vrag. Die eerste waardebepaling van verspreidingseenheid afgooi het aangedui dat 30‐50% van hierdie verspreidingseenhede die ontvanger omgewing sal binnedring. Verdere resultate het voorgestel dat die konstruksie van die Britse Antarktiese Opname Halley VI stasie die vervoer van 5000 sade van 34 taxa sal fasiliteer die streek in, wat dit ’n betekenisvolle weg maak vir indringings. Verspreidingseenheid druk is ook, as gevolg van die SANAP logistiek, aanmerklik vir mariene spesies. Vuilgoed versamelings op die eksterne omhullende oppervlaktes van die SANAP her‐voorsieningsvaartuig, die SA Agulhas, vorm wanneer die vaartuig se anti‐vuilgoed verf beskadig is met reis deur see‐ys en word gekenmerk deur lae diversiteit. Ys skuring voorkom dat vuilgoed versamelings vervoer word na die Antarktiese kontinent, maar versamelings bly grootliks vasgeheg wanneer na sub‐Antarktiese eilande gereis word. Populasies van ’n welbekende indringer, Mytilus galloprovincialis, is gevind in die see‐storingsarea van die vaartuig, met sommige individue wat die vervoering na die Antarktiese streek oorleef het op verskeie geleenthede. Wanneer spesies die aanvanklike verspreidingshindernisse oorkom het, staar hulle verdere ekologies en fisiologiese uitdagings in die gesig ten einde in die ontvanger streek te vestig. Die parasitiese wespe Aphidius matricariae is vir die eerste keer op Marion aangeteken in 2001. Opnames om die eiland toon dat volwasse oorvloed en die frekwensie van plantluis parasitisme die hoogste is aangrensend die algemene ankerpunt van die SA Agulhas en afneem weg van die omgewing af. Genetiese diversiteit was laag, wat voorstel dat die populasie gevestig het van ’n enkele bekendstelling. Dit lig uit dat hoë verspreidingseenheid druk nie nodig is vir die suksesvolle vestiging van bekendgestelde invertebrata nie. ‘n Ander spesie wat die verspreidingshindernisse oorkom het is die landslak Deroceras panormitanum wat in die 1970’s op Marion Eiland bekendgestel is en wat sedertdien versprei het oor meeste van die kushabitat van die eiland. Vir hierdie spesie word grens limiete vasgestel deur onverdraagsaamheid vir lae temperature en saliniteit en die oorvloedstruktuur word gekenmerk deur laslappe en gapings wat geassosieer word met die spesie se onvermoë om droë kondisies te hanteer. Om verdere uitheemse bekendstellings in die streek te voorkom, word geteikende bestuur van hoë risiko weë vereis. Toenemende waaksamheid is bykomend nodig vir die opsporing en bestuur van nuutgevestigde uitheemse spesies voordat hulle grense verbreed.

Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: South Africa is known for its high marine invertebrate diversity but the evolutionary histories of these species are largely unknown. The present study contributes to the growing body of phylogeographic studies of southern African coastal species. The main aim is to better understand the colonization and diversification of South African barnacles. To investigate the phylogeographic pattern in the southern African volcano barnacle, Tetraclita serrata, 410 individuals from 20 sampling localities were analyzed. In addition, to understand the colonization and diversification patterns of South African barnacle species, nine taxa were included in a molecular phylogeny derived from the nuclear gene, 18S rRNA. With only a limited number of 18S sequences available on GenBank, a separate phylogenetic tree, for the mitochondrial gene, was constructed to determine whether the genus Tetraclita is monophyletic. Restricted gene flow in some geographical areas was hypothesized for T. serrata based on oceanic circulation patterns; known biogeographic regions; and features such as the Agulhas Bank, which has shaped the population genetic structure of several other South African marine organisms. The population genetic structure was investigated using the mitochondrial cytochrome oxidase subunit 1 (CO1) and nuclear internal transcribed spacer 1 (ITS1) genes. Phylogenetic and population genetic analyses of the CO1 gene revealed two distinct genetic clades with overlapping distributions. The nuclear ITS1 data performed on a subset of individuals drawn from both mtDNA clades revealed a single lineage. The pattern observed can be ascribed to a historical event that may have been responsible for the formation of allopatric lineages that have since come into secondary contact. On the other hand, the pattern observed may be as result of incomplete sorting of nDNA alleles, in which case, given that the two mtDNA clades are not geographically isolated, could be explained by selective pressures acting on the species due to ecological constraints. No clear phylogeographic structure was found within each of these clades and the direction of gene flow of T. serrata individuals can be linked to the oceanographic features found along the South African coast. In contrast to most other South African marine species studied to date, the haplotype network, mismatch distributions and time since expansion suggest that the effective population size of T. serrata was not severely affected by the Last Glacial Maximum. It is proposed that further investigations into the phylogeography of coastal marine species, particularly obligatory sessile species such as barnacles, are required to determine whether the patterns observed in T. serrata is a rare history, or not. Neighbour-joining, maximum parsimony and Bayesian analyses on the CO1 gene provide evidence for the monophyly of the genus Tetraclita; however, Tetraclita species found in South Africa do not share a common ancestry suggesting multiple colonization events. This study has also accidently led to the discovery of an introduced species, Balanus perforatus, native to Europe, and I discuss the potential of the alien becoming invasive on the east coast of South Africa where it was found. / AFRIKAANSE OPSOMMING: Suid-Afrika is bekend vir sy hoë mariene ongewerwelde diversiteit, maar die evolusionêre geskiedenis van hierdie spesies is grootliks onbekend. Hierdie studie is gedoen om by te dra tot die filografiese studies van suider Afrikaanse kus spesies en om die kolonisasie en diversifikasie van die Suid-Afrikaanse eendmossels beter te verstaan. Om die genetiese struktuur van die bevolkings van die vulkaan eendmossel, Tetraclita serrata, wat langs die Suid-Afrikaanse kuslyn voorkom, te bestudeer, was 410 individue van 20 lokaliteite ontleed. Daarbenewens, om die kolonisasie en diversifikasie van Suid-Afrikaanse eendmossels te verstaan, was nege spesies ingesluit in 'n molekulêre filogenie wat gebaseer is op die kern geen, 18s rRNA. Met slegs 'n beperkte aantal 18s DNS volgordes beskikbaar op GenBank,is 'n aparte filogenetiese boom, vir die mitochondriale geen COI, gekonstrueer om te bepaal of die genus Tetraclita monofileties is. Beperkte geen-vloei in sommige geografiese gebiede was verwag vir T. serrrata gebaseer op oseaniese sirkulasiepatrone; bekende biogeografiese streke, en kenmerke soos die Agulhas Bank, wat die filogeografiese struktuur van verskeie ander Suid- Afrikaanse mariene organismes beïnvloed het. Die genetiese struktuurvan die bevolkings is geondersoek met behulp van die mitochondriale sitochroom oksidase subeenheid 1 (COI) en kern interne getranskripeerde spasieërder 1 (ITS1) gene. Geen duidelike bevolkings genetiese struktuur is gevind nie en die rigting van geenvloei van T. serrata individue kan gekoppel word aan die oseanografiese kenmerke wat langs die Suid-Afrikaanse kus voorkom. Filogenetiese en bevolking genetiese ontleding van die COI geen openbaar twee afsonderlike klades maar met oorvleuelende geografiese verspruidings. Die ITS1 data-analise wat uitgevoer was op 'n subset van individue wys op 'n enkele spesie. Die waargenome patroon dui op 'n belangrike historiese verskil tussen die twee klades. 'n Geskiedkundige gebeurtenis was dalk verantwoordelik vir die vorming van twee evolusionêre lyne wat sederdien sekondêre kontak het. Aan die ander kant, kan die patroon waargeneem word as gevolg van die onvolledige sortering van nDNA allele, in welke geval, gegee dat die twee mtDNA clades nie geografies geïsoleer is nie, dit verduidelik kan word deur selektiewe druk wat op die spesie was as gevolg van fisiologiese of ekologiese beperkings. Die statistiese parsimonie netwerk, ongelyksoortige verspreidings en tyd sedert die bevolkingsuitbreiding dui daarop dat T. serrata die laaste ysagtige maksimum tydperk oortleef het. Tot op hede het geen Suid- Afrikaanse mariene spesies so 'n patroon gewys nie. So, verdere ondersoeke in die filogeografie van die kus mariene spesies, veral verpligte sittende spesies soos eendmossels, word vereis om te bepaal of die patroon waargeneem in T. serrata 'n seldsame geskiedenis het, of nie. Buur-aansluiting, maksimum parsimonie en Bayesian afleiding op die CO1 geen het bewyse verskaf vir die monofiletiese afkoms van die genus Tetraclita, maar Tetraclita spesies wat in Suid Afrika gevind is, deel nie ‘n gemeenskaplike afkoms nie, wat weer bewyse verskaf vir verskeie kolonisasie gebeure. Hierdie studie het gelei tot die ontdekking van 'n eksotiese spesie, Balanus perforatus, inheems aan Europa, en die potensiaal van die indringer om ontwykend te raak aan die ooskus van Suid-Afrika waar dit gevind is word bespreek. / The South African National Research Foundation (NRF) and Stellenbosch University

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In southern Africa, the ticks Amblyomma hebraeum and Hyalomma rufipes are the main vectors of animal Heartwater and human Crimean Congo Haemorragic Fever, respectively. In order to investigate the phylogeographic structure of these ectoparasites, population genetic studies were conducted throughout southern and partly eastern Africa. Knowing the levels of genetic diversities and population connectivities throughout the species’ native ranges, may be useful for implementing control measures (cross country borders for example), evaluate the potential for drug resistance in introduced locations as well as for elucidating its vectorial capacities in the region. Mitochondrial cytochrome oxidase I (COI) and the internal transcriber spacer 2 (ITS-2) sequences were obtained from eleven sampled localities. In general, haplotype networks and molecular diversity values showed significant genetic structure between most of the sampled populations. Fu’s Fs and mismatch distributions suggested recent population expansions following a bottleneck. A Mantel regression analysis also revealed a significant isolation by distance for H. rufipes. Comparing the two species, H. rufipes showed much stronger signals of geographic genetic population structure in relation to A. hebraeum. A single taxonomic unit is suggested for A. hebraeum while H. rufipes is characterized by the existence of at least three distinct genetic assemblages that may point to incipient speciation. The difference between the two species may be explained by gene flow restriction within the region, by the number of hosts required to complete the life cycle (2 and 3 hosts, respectively), type of host species (domestic and wild animals; small and big mammals, birds) and its availability, and host species overlap. Also, a geographic break between possible host species during the Pleistocene, domestication of animals and climatic conditions in the region played a role on the genetic structure of H. rufipes. / AFRIKAANSE OPSOMMING: Die suider Afrikaanse bosluise, Amblyomma hebraeum en Hyalomma rufipes is die hoof vektore van Hartwater in diere en Crimean Kongo Haemorargiese koors in mense. Om die filogeografiese struktuur van hierdie ektoparasiete te ondersoek, is bevolking-genetiese studies uitgevoer in suidelike Afrika asook gedeeltelik in oos Afrika. Deur die vlakke van genetiese diversiteit en bevolkingsverbindings regdeur die spesies se natuurlike verspreiding te weet, sal dit dalk moontlik wees om: beheermaatreëls (byvoorbeeld oorgrens) in te stel, die waarskynlikheid van weerstandbiedendheid in nuut losgelate gebiede te verstaan, en meer insigte in die vektoriale kapasiteit te verkry. Mitochondriale sitochroom oksidae (COI) en die interne transkriberende spasieerder 2 (ITS- 2) basisnukleotiedopeenvolgings van elf bevolkings is versamel. Haplotiepe netwerke en molekulêre diversiteitwaardes het in die algemeen, betekenisvolle genetiese verkille tussen meeste van die versamelde bevolkings aangetoon. Fu’s Fs en gemiste-paringverspreidings het voorgestel dat die bevolkings onlangs uitgebrei het nadat hulle 'n bottelnek ondergaan het. 'n Mantel regressie analise het ook betekenisvolle isolasie met afstand aangetoon vir H. rufipes. As die twee spesies vergelyk word het H. rufipes baie sterker seine van genetiese geografiese bevolkingstruktuur gewys as A. hebraeum. 'n Enkele taksonomiese eenheid word voorgestel vir A. hebraeum terwyl H. rufipes gekarakteriseer word deur ten minste drie taksonomiese eenhede. Die verskil tussen die twee spesies kan moontlik verklaar word deur geen-vloeibeperkings in die gebied, die aantal gasheer spesies wat benodig word om die lewenssiklus te voltooi (2 of 3 gashere onderskeidelik), tipe gasheer (domestikeerd- of wildlewend; klein of groot soogdiere, voëls) en hulle beskikbaarheid, en die gasheerspesies se oorvleueling. Dit is ook moontlik dat 'n geografiese breek tussen moontlike gasheerspesies gedurende die Pleistoseen, domestikering van diere en klimaatstoestande in die streek 'n rol kon speel by die genetiese struktuur van H. rufipes. / The NRF and the University of Stellenbosch for funding and bursary

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: To predict the influence of temperature increases on organisms, and their capacity to respond to climate change, information on the upper thermal tolerance of organisms and its plasticity is required. However, various factors, such as rate of temperature change, may influence basal thermal tolerance and plastic responses, and consequently the vulnerability of organisms to temperature change. Although slower rates of temperature change might be more ecologically relevant, the majority of thermal tolerance studies feature rates of temperature change that are faster than those experienced by organisms in nature. Additionally, studies using slower rates of temperature change have been criticized as factors such as changes in body condition and accumulation of stress over time may confound results. This study determined the influence of fast and slow rates of temperature change and plasticity, induced by acclimation to different temperature conditions for 5 – 15 days, on the upper thermal tolerance of marine amphipod and isopod species from sub-Antarctic Marion Island and South Africa. Using congeners, intra- and inter-specific comparisons of the upper thermal tolerance and plasticity of these organisms were made across geographical regions (South Africa vs. Marion Island), across sites within regions (West coast vs. South coast of South Africa) and between tidal zones. Overall, lower rates of temperature change were found to be associated with lower values of upper thermal tolerance. At fast rates of temperature change, acclimation at high temperatures was associated with an increase in thermal tolerance, whereas at slow rates, acclimation to higher temperatures either had no effect or caused a decrease in thermal tolerance. Furthermore, microclimate recordings suggest that these organisms likely experience rates of temperature increase that are intermediate between the fast and slow rates employed in this study. Thus, in nature these marine invertebrates have upper thermal tolerances that are higher than mean environmental temperature and can likely mount plastic responses during short-term temperature variation. At slow rates of temperature change, however, the upper thermal tolerance of these organisms approximates environmental temperature and plasticity is reduced, likely increasing vulnerability to high temperatures. At the intra-specific level, upper thermal tolerance and plasticity response varied based on mass and sex, however, these effects were species-specific. Isopods inhabiting cooler but more variable microsites on the West coast of South Africa had a higher upper thermal tolerance, but similar magnitude of plasticity, than a population of the same species from the warmer, less variable South coast. Generally, Marion Island species had a lower upper thermal tolerance but higher magnitude of plasticity than South African species. The variability reported here at different hierarchical and geographical scales could be linked to the distinct thermal environments experienced, and the differing physiological and behavioural responses of populations and species to their thermal environments. This variation in thermal tolerance might be critical during environmental change and suggests that species composition may be altered in the future. / AFRIKAANSE OPSOMMING: Om die invloed van temperatuur verhogings op organismes, en hul vermoë om te reageer op hierdie verandering, te voorspel, word inligting oor hoë temperatuur verdraagsaamheid van organismes en die plastisiteit hiervan, benodig. Verskeie faktore, soos die tempo van verandering, kan egter basale termiese verdraagsaamheid en plastiese reaksies beïnvloed. Dus, mag dit die tasbaarheid vir temperatuur verandering beïnvloed. Alhoewel stadiger tempo van verandering meer ekologies relevant kan wees, fokus die meerderheid van warm verdraagsaamheid studies op temperatuur veranderinge wat vinniger gebeur as wat ervaar word deur organismes in die natuur. Boonop word studies wat fokus op stadige veranderinge in temperatuur, gekritiseer omdat faktore soos ‘n verandering in liggaamstoestand en die opeenhoping van stres, potentieël die resultate kan belemmer. Hierdie studie ondersoek die invloed van vinnige en stadige temperatuur veranderinge en die plastisiteit, geïnduseer deur akklimasie, met betrekking tot verskeie temperature vir 5-15 dae. Ons fokus spesifiek op die hoë temperatuur verdraagsaamheid van mariene amphipod- en isopod spesies van sub-Antarktiese Marion Island en Suid Afrika. Deur gebruik te maak van spesies wat aan dieselfde genus behoort, is vergelykings getrek tussen intra- en inter-spesies verbande met betrekking tot hul termiese verdraagsaamheid en plastisiteit. Die studie is oor geografiese streke (Suid Afrika vs. Marion Island), tussen areas binne ‘n geografiese streek (Weskus vs. Suidkus van Suid Afrika) en tussen gety sones voltooi. Oor die algemeen was stadige temperatuur veranderinge geassosieër met ‘n laer termiese verdraagsaamheid vir hoë temperature. Met vinnige veranderinge in klimaat, was akklimasie by hoë temperature geassosieër met ‘n hoër temperatuur limiet, maar by stadige temperatuur veranderinge het akklimasie by hoë temperature geen effek gehad nie, of het ‘n afname in termiese verdraagsaamheid veroorsaak. Verder het mikroklimaat opnames aangedui dat hierdie organismes waarskynlik temperatuur verhogings ondervind in hul natuurlike habitat, wat intermediêre is van die vinnige en stadige veranderinge wat in hierdie studie gebruik is. Dus, in die natuur, het hierdie mariene invertebrate `n boonste termiese toleransies wat hoër is as die gemiddelde omgewingstemperatuur en kan hulle waarskynlik van platiese reaksies gebruik maak tydens kort-termyn temperatuur variasie. Gedurende stadige temperatuur veranderinge toon hulle alhoewel hoë termiese verdraagsaamheid teenoor die omgewingstemperature en plastisiteit is verminder, wat heel waarskynlik toenemende kwesbaarheid vir hoë temperature tot gevolg het. Op die intra-spesifieke vlak was wisseling in hoë termiese verdraagsaamheid gebaseer op liggaams massa en geslag, maar hierdie veskille was spesie-spesifiek. Isopoda wat koeler areas bewoon, met meer variasie in hul mikroklimaat, soos ondervind in die Weskus van Suid Afrika, het `n hoër termiese verdraagsaamheid. Maar, soortgelyke mate van plastisiteit, as 'n populasie van dieselfde spesie van die warmer, minder veranderlike Suidkus. Oor die algemeen het Marion-eiland spesies 'n laer termiese verdraagsaamheid, maar hoër grootte van plastisiteit as Suid-Afrikaanse spesies. Die veranderlikheid wat hier geraporteer is, kan op verskeie hiërargiese en geografiese vlakke gekoppel wees aan die unieke termiese omgewings wat hierdie organismes ervaar en aan die verskillende fisiologiese- en gedrags reaksies van populasies en spesies tot hulle termiese omgewings. Die variasie in termiese verdraagsaamheid kan krities wees tydens omgewingsverandering en dui daarop dat spesie-samestelling kan verander in die toekoms. / The British Antarctic Survey for funding

Thesis (MSc)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Opisthopatus cinctipes is a velvet worm endemic to South Africa and is widely distributed in isolated Afromontane and coastal forest patches throughout the Eastern Cape, KwaZulu-Natal and Mpumalanga. The species, like most velvet worms is characterized by low vagility, microhabitat specialization and is hypothesized to harbor significant cryptic diversity. We used partial sequence data derived from three partial mitochondrial (mtDNA) gene loci (COI, 12S rRNA and 16S rRNA) and a partial nuclear gene fragment (18S rRNA), as well as gross morphological character analysis and scanning electron microscopy (SEM) to determine evolutionary relationships amongst a total of 120 specimens of O. cinctipes from 33 localities. Phylogenetic relationships were investigated using Bayesian inferences, Maximum Parsimony and Maximum Likelihood analysis. Phylogenetic analysis of mtDNA and nDNA data revealed the presence of multiple cryptic lineages nested within Opisthopatus cinctipes with at least nine distinct well supported clades (> 70% / > 0.95 pP), suggesting that the taxon comprises a “species complex”. Afrotemperate forest specimens were genealogically highly distinct from each other whilst Indian Ocean Coastal Belt forest (at least in KwaZulu-Natal) specimens were more closely related and formed a well supported clade. An analyses of molecular variance indicated that (ΦST) 89.31% of the genetic variation occurred amongst localities. Highly significant FST values were generally observed across sampled localities (FST = 0.89, p < 0.001). Tajima’s D value was 0.83 over all sampled localities, implying a decrease in population size and/or balancing selection. Uncorrected pairwise sequence divergence values between O. cinctipes localities for the COI locus were high and ranged from 3.20% to 19.50%. No haplotypes were shared between localities. There is considerable evidence showing that past geological events may have shaped the deep genetic divergences observed between sampling localities suggesting the absence of gene flow. Genetic divergences within the South African O. cinctipes species complex are shown to have occurred from the onset of the Cenozoic era. The genetic variation observed within clades was not accompanied by morphological differences suggesting that the use of morphological characters has grossly underestimated species diversity within South African Opisthopatus. A robust taxonomic documentation of the species diversity within the O. cinctipes species complex is critical for the implementation of conservation management plans for this species complex. We recommend that highly sedentary taxa with limited dispersal abilities and specific habitat requirements which may be found in sympatry with velvet worms be prioritized for taxonomic revision as they may also harbor cryptic lineages. / AFRIKAANSE OPSOMMING: Geen Afrikaanse opsomming beskikbaar.

The need to understand the dynamics of the impala population in Mkuzi Game Reserve arose during the early 1960's when it became clear that various factors were contributing to an overpopulation of the species in the reserve. Population management was recognized as being necessary and was carried out, but it was based on inadequate information. This study set out to establish a rational basis for future management. The social organization and behaviour of impala in Mkuzi were analysed and placed in perspective relative to the population dynamics. Two methods of counting the animals were used and a relationship obtained between the respective results. The distribution of impala within the reserve, both on a gross population basis and with respect to the various sex and age categories, was determined from sampling. In order to establish the age structure of the population, samples obtained from the control programme were used, and these were aged on the basis of molar wear. At the same time the proportions of young animals and the population sex ratios were obtained by field sampling. Using these data, life tables were constructed, from . which it was possible to interpret the behaviour of the population at the time of the study. However, caution should be exercised in extrapolating these results literally to the same population under different conditions. The study only provides guidelines for regular monitoring to be carried out. At the same time a more detailed study of the vegetation dynamics of Mkuzi Game Reserve is a priority so that the relationship between the animal and plant elements of the reserve can be properly analysed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1979.

This study deals with the three orders of Squamata (Sauria, Amphisbaenia, Serpentes) of the Orange Free State, South Africa. Following an intensive systematic survey 4 492 specimens have been examined comprising 77 different species and subspecies of which 25% represent new records for the study area. Variation in taxonomically important characters as well as informa- tion on colour, size, habitat, breeding, predators and diet are discussed. Certain taxonomic changes have been made. Distribution maps have been compiled on the basis of eighth-degree-units. Distributional patterns have been analyzed to establish areas of relative homogeneity separated by transitional zones. A causal analysis of the main distribution patterns of the O.F.S. Squamata indicated that rainfall is the major environmental factor influencing distribution. A comparative analysis of the squamate areas has been done with regard to various biogeographic phenomena. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.

Abstract available in PDF file. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.

This study focuses on the effective biocontrol agent Chilocorus nigritus (Fabricius). Its behaviour and ecology were compared with other Chilocorus spp. where appropriate, to elucidate why this species is such an effective biocontrol agent, and how to improve methodology for its deployment as a natural enemy. An artificial diet for C. nigritus was developed, but was still sub-optimal. Asterolecanium miliaris (Boisduval) was a suitable prey for all life stages of C. nigritus and the adults of Chilocorus bipustulatus (Linnaeus) and Chilocorus infernalis Mulsant, but was inadequate for larvae of the last two species. Adult weight, measured at one day after adult eclosion, was an appropriate indicator of the effects of larval treatment on their development and on the fitness of subsequent adults. There was no improvement in culture vigour due to a behavioural response of individuals within one generation to fluctuating as opposed to constant temperature. starvation for between 10h and 24h was appropriate for standardisation of hunger. Measuring feeding rate at a range of static temperatures did not reflect differences in the climatic adaptations of six Chilocorus spp., but mortality rates at increasingly high temperatures were useful. Chilocorus spp. showed little ability to choose between prey species. Prey substitutions adversely affected adults and larvae. Introduction of adults was the most effective method for field establishment. Giant bamboo Dendrocalamus giganteus Munro was a valuable site for field releases of C. nigritus, but less useful for C. bipustulatus and C. infernalis. Counter to assumptions on which interference models have been based, no significant intraspecific interference, reducing predatory efficiency, was observed. Visually prominent features on the horizon and a specific leaf shape, were attractive to foraging C. nigritus. The location of prey patches by adults was facilitated by prey odour, but not so for larvae. Adults detected individual prey olfactorily and visually over short distances, but physical contact was required for detection by larvae. Prey location by larvae and adults was facilitated by alterations in movement patterns in response to prey consumption. Differences in prey detection and the effects of prey substitutions, between the life stages, were related to field behaviour. The relevance to biological control, of responses to rearing conditions and feeding and foraging behaviour, was investigated. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1991.