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Cellular biomarkers of exposure to the fungicide copper oxychloride, in the common garden snail Helix aspersa, in Western Cape vineyardsSnyman, Reinette Georgenie 03 1900 (has links)
Thesis (PhD(Agric)(Botany and Zoology))--University of Stellenbosch, 2001. / Copper oxychloride (Cu2CI(OH)3) is a broad-spectrum fungicide, intensively sprayed in many South
African vineyards and orchards. It is necessary to find accurate and effective methods of monitoring the
effects of this fungicide on the biota of the agricultural environment. The use of biomarkers may be a
possible method to employ for this purpose.
This study investigated the effects of copper, as a result of copper oxychloride exposure, on the biology
of the common garden snail Helix aspersa, as welI as a number of cellular responses to exposure to the
fungicide. The possible use ofthese responses as biomarkers was also investigated.
Two groups of snails were exposed to 80 and 240 tJg g-! copper oxychloride respectively, for six
weeks. A third group served as control. On a weekly basis, body mass, number of eggs produced,
neutral red retention (NNR) times of haemocytic lysosomes, and body copper concentrations were
determined for each individual. At the end of the experiment, the digestive glands, ovotestes and
hermaphrodite ducts of a number of snails were prepared for histological analysis. The following
parameters were investigated: tubule area, epithelium height and area in the digestive gland,
spermatozoan area in the vesicula seminalis and ovotestis, as wen as oocyte numbers in the ovotestis.
To test the validity of the laboratory results, a field survey was conducted. Snails were colIected from
an uncontaminated vineyard and on two occasions from a contaminated vineyard in the Western Cape.
The same cellular responses were investigated as in the laboratory study.
The results showed that growth, egg production and hatching success in Helix aspersa were affected by
experimental exposure to copper oxychloride. In both the laboratory study and field survey, copper in
the body of H. aspersa was shown to be compartmentalized and the digestive gland was the most
important site of copper accumulation. NNR times of haemocytic Iysosomes were shown to be affected
by copper oxychloride exposure, already during the first week of exposure. A time evolution of copper
accumulation and lysosomal damage existed. Epithelium height and area of digestive gland tubules,
and spermatozoan and oocyte densities in the ovotestis, were also affected by copper oxychloride
exposure and the concomitant copper burdens in the respective organs. Through the field survey it was
ascertained that these histopathological changes were largely dependent on exposure time. It was concluded that lysosomal response of H. aspersa haemocytes, as measured by the NNR time
assay, could be considered a useful biomarker of copper oxychloride exposure, since it provides an
early warning of stress induced by this fungicide. Changes in digestive gland epithelium cells, and
gametes in the ovotestis, can also possibly serve as biomarkers of copper oxychloride exposure.
However, these can not serve as an early warning. All of the cellular responses identified in the present
study can be used in combination with other cellular and physiological parameters and toxicological
endpoints in order to improve the reliability and accuracy of interpretations regarding cause and effect.
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Phylogeny of Ameronothroidea in the south polar region and the phylogeography of selcted species on sub-antarctic Marion IslandMortimer, Elizabeth 03 1900 (has links)
Thesis (DPhil)--University of Stellenbosch, 2008. / ENGLISH ABSTRACT: Sub-Antarctic islands represent the only mid to high latitude terrestrial biomes in the Southern Hemisphere. These
islands have various geological origins and histories, well-preserved terrestrial ecosystems and high levels of
species endemism. In an attempt to understand the evolution and biogeography of terrestrial taxa in the South
Polar Region, the first broad-scale molecular phylogeny was constructed for the unique terrestrial group, the
ameronothroid mites (genus Halozetes (Oribatida)), collected from sub-Antarctic and Maritime Antarctic localities.
Phylogenetic analyses based on a combined mitochondrial (cytochrome oxidase subunit I (COI)) and nuclear
(histone-3 (H3)) sequence dataset indicated that the evolution of these mites were habitat specific (i.e. intertidal,
supralittoral and terrestrial). Notwithstanding criticisms levelled against a molecular clock, the mites were
evolutionary young (<10myo), contrary to their status as an ancient group predating Gondwana fragmentation.
Biogeographic analyses indicated a complex pattern mainly sculpted by multiple independent dispersal events
across the Antarctic Polar Frontal Zone similar to previous findings for other marine and terrestrial taxa. Also, the
molecular phylogeny displayed considerable discourse with contemporary taxonomy suggesting the need for
taxonomic revisions and reassessment of morphological characters. Sub-Antarctic Marion Island, the larger of the
two islands comprising the Prince Edward Island archipelago (PEI), has experienced extensive glaciation and
volcanism. To assess the impact of historical events (volcanism (including recent eruptions) and glaciation) and
contemporary mechanisms (gene flow) on the genetic spatial distribution of species from Marion Island, two mite
species namely Eupodes minutus (Prostigmata) and Halozetes fulvus (Oribatida) as well as a single plant species,
Azorella selago (Apiaceae), were selected as model organisms. For independent phylogeographic analyses,
mitochondrial sequence data (COI) were obtained for both mite species, while chloroplast sequence (trnH-psbA)
and amplified fragment length polymorphism (AFLP) data were generated for the cushion plant, A. selago. Since
A. selago is typified by two growth forms namely discrete cushions and continuous mats, it was essential to
examine the growth dynamics prior to phylogeographic analyses. The sequence and fragment data indicated that
both mite and plant species were significantly substructured across Marion Island. Manual comparisons indicated
unique populations on the western (Kaalkoppie for H. fulvus, La Grange Kop for E. minutus and Mixed Pickle for
A. selago), eastern (Bullard Beach for H. fulvus and Kildalkey Bay for E. minutus), northern (Middelman and Long
Ridge for H. fulvus) and southern side (Grey Headed for H. fulvus and Watertunnel for A. selago) of the island.
Importantly, the western side had unique localities for all species. Interestingly, based on the H. fulvus data, the
western populations were relatively young, characterized by high migration rates, small effective (female)
population sizes with no isolation-by-distance. The opposite scenario was found for the eastern populations. This
spatial genetic structure described for species on Marion Island can be ascribed to both historical events and
environmental conditions. These areas with their unique genetic composition are of special conservational
concern; consequently this research will contribute to an active management plan for PEI, South Africa’s only
Special Nature Reserve. / AFRIKAANSE OPSOMMING: Sub-Antarktiese eilande verteenwoordig die enigste terrestriële bioom in die middel tot hoër breedtegrades van
die Suidelike Halfrond. Hierdie eilande besit ‘n verskeidenheid van geologiese oorspronge en geskiedenisse,
goed-bewaarde terrestriële ekosisteme en hoë vlakke van endemisme. In ‘n poging om die evolusie en
biogeografie van terrestriële taksa in die Suid Pool Area te verstaan, is die eerste grootskaalse molekulêre
filogenie saamgestel vir ‘n unieke terrestriële groep, die ameronothoïed miete (genus Halozetes (Oribatida:
Ameronothroidea)), vanaf menigte sub-Antarktiese en Maritime Antarktiese lokaliteite. Filogenetiese analises
gebaseer op die saamgestelde mitochondriale (sitokroom oksidase subeenheid I (COI)) en nukluêre (histoon-3
(H3)) basispaarvolgordes het aangedui dat die evolusie van hierdie miete habitat spesifiek is (m.a.w inter-gety,
supralitoraal en terrestrieël). Ongeag die kritiek teenoor ‘n molekulêre klok, is hierdie miete evolusionêr jonk
(<10mjo), wat teenstrydig is met hulle status as ‘n antieke groep wat terugdateer voor Gondwana fragmentasie.
Biogeografiese analises het ‘n komplekse patroon aangedui wat grotendeels gekarakteriseer word deur menigte
onafhanklike verspreidingsgebeurtenisse bo-oor die Antarktiese Polêre Frontale Zone, wat ooreenstemmend is
met vorige bevindinge vir ander mariene en terrestriële taksa. Die molekulêre filogenie het ook aansienlik verskil
van die tradisionele taksonomie, dus is taksonomiese aanpassings en herklassifisering van morfologiese
karakters noodsaaklik. Sub-Antarktiese Marion Eiland, die groter eiland van die Prins Edward eilandgroep (PEI),
het uitermate glasiasie en vulkanisme ondervind. Om die impak van historiese gebeurtenisse (vulkanisme
(insluitend onlangse uitbarstings) en glasiasie) en kontemporêre meganismes (geenvloei) op die genetiesgespasieërde
verspreiding van spesies vanaf Marion Eiland te bepaal, was twee mietspesies naamlik Eupodes
minutus (Prostigmata) en Halozetes fulvus (Oribatida) asook ‘n enkele plantspesie, Azorella selago (Apiaceae),
gekies as model organismes. Vir onafhanklike filogeografiese analises, was die mitochondriale basispaarvolgorde
(COI) vir beide mietspesies bepaal, terwyl chloroplast basispaarvolgorde (trnH-psbA) asook geamplifiseerde
fragmentlengte polimorfisme (AFLP) data gegenereer was vir die kussingplant, A. selago. Aangesien A. selago
gekenmerk word deur twee groeivorme, naamlik diskrete kussings en aaneenlopende matte, was dit noodsaaklik
om eers die groeidinamika van die plant te ondersoek alvorens ‘n filogeografiese studie kon geskied. Die
basispaarvolgordebepalings en fragmentdata het aangedui dat beide mietspesies sowel as die plantspesie
betekenisvolle substruktuur vertoon regoor Marion Eiland. Informele vergelykings het unieke populasies aangedui
op die westelike (Kaalkoppie vir H. fulvus, La Grange Kop vir E. minutus en Mixed Pickle vir A. selago), oostelike
(Bullardstrand vir H. fulvus en Kildalkeybaai vir E. minutus), noordelike (Middelman en Long Ridge vir H. fulvus) en
suidelike kant (Grey Headed vir H. fulvus en Watertunnel vir A. selago) van die eiland. Die westelike kant besit
dus unieke lokaliteite vir al die spesies. Interressantheidhalwe het die H. fulvus data getoon dat die westelike
populasies relatief jonk is en gekarakteriseer word deur hoë migrasiesyfers en klein effektiewe (vroulike)
populasiegroottes met geen isolasie-oor-afstand nie. Die resultate vir die populasies aan die oostelike kant van die
Marion Eiland was presies teenoorgesteld. Dié beskryfde substruktuur vir die spesies op Marion Eiland is
afkomstig van beide historiese gebeurtenisse asook omgewingstoestande. Hierdie areas met hul unieke genetiese samestelling, is belangrik vir natuurbewaring. Hierdie navorsing sal bydra tot die bestuursriglyne van PEI, Suid
Afrika se enigste Spesiale Natuurreservaat.
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Alien invaders and reptile traders : risk assessment and modelling of trends, vectors and traits influencing introduction and establishment of alien reptiles and amphibiansVan Wilgen, Nicola Jane 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Biological invasions are a growing threat to biodiversity, trade and agriculture in South Africa.
Though alien reptiles and amphibians (herpetofauna) are not currently a major issue, escalating
problems worldwide and increased trade in South Africa suggest a possible increase in future
problems. In this thesis I explore practical measures for risk assessment implementable under
national legislation. I began by documenting record-keeping and legislative differences between
provinces in South Africa. This revealed some serious deficiencies, complicating attempts to
compile accurate inventories and discern import trends. International trade data, however,
revealed an exponential increase in the number of imports to South Africa over the last 30 years.
Characterising the abundance of species in this trade is important as species introduced in large
numbers pose a higher establishment risk. In South Africa, I found a tendency for venomous and
expensive species to be traded in low numbers, whereas species that are easy to breed and handle,
or that are colourful or patterned are traded in higher numbers.
Unlike South Africa, California and Florida have had a large number of well-documented
herpetofaunal introductions. These introductions were used to verify the role of several key
predictors in species establishment. I first evaluated the role of each variable separately. I
examined different approaches for bioclimatic modelling, the predictive power of different sources
of distribution data, and methods of assigning a climate-match score. I also present the first test of
Darwin’s naturalization hypothesis for land vertebrates using two new phylogenies inferred for
native and introduced reptiles in California and Florida. I then used boosted regression trees (BRT)
to infer the relative contribution of each factor to species establishment success. Results from the
BRTs were incorporated into a user-friendly spreadsheet model for use by assessors inexperienced in
complex modelling techniques.
Introduction effort was found to be the strongest contributor to establishment success.
Furthermore, species with short juvenile periods were more likely to establish than species that
started breeding later, as were species with more distant relatives in regional biotas. Average
climate match and life form were also important. Of the herpetofaunal groups, frogs and lizards
were most likely to establish, while snakes and turtles established at much lower rates, though
analysis of all recorded herpetofaunal introductions shows slightly different patterns. Predictions
made by the BRT model to independent data were relatively poor, though this is unlikely to be
unique to this study and can be partially explained by missing data. Though numerous uncertainties
remain in this field, many can be lessened by applying case by case rules rather than generalising
across all herpetofaunal groups. The purpose for import and potential trade volume of a species will
influence the threat it poses. Considering this in conjunction with a species’ environmental
tolerances and previous success of species with similar life histories, should provide a reasonable
and defendable estimate of establishment risk. Finally, a brief summary of the potential impacts of
introduced alien herpetofauna is provided in the thesis. / AFRIKAANSE OPSOMMING: Indringer spesies hou ‘n al groter bedreiging in vir die biodiversiteit, handel en landbou van Suid-
Afrika. Alhoewel uitheemse reptiele en amfibieërs (herpetofauna) tans nie ‘n groot bedreiging in
Suid-Afrika is nie, dui groeiende probleme wêreldwyd asook 'n toename in plaaslike handel op
moontlike toekomstige probleme. In hierdie tesis, ondersoek ek praktiese metodes vir risikobepaling
wat onder nasionale wetgewing toegepas kan word. Ek begin deur die verskille in stoor van rekords
en wetgewing tussen provinsies te dokumenteer. Hierdie proses het ernstige tekortkominge
uitgewys, wat pogings om akkurate inventarisse saam te stel en invoertendense te bepaal,
bemoeilik. Internasionale handelsdata het egter getoon dat daar ‘n eksponensiële toename in die
hoeveelheid invoere na Suid-Afrika oor die laaste 30 jaar was. Die hoeveelheid spesies in hierdie
handel is belangrik omdat spesies wat in groot hoeveelhede ingevoer word, ‘n hoër vestigingsrisiko
het. In Suid-Afrika is ‘n tendens gevind vir handel in giftige en duur spesies teen lae hoeveelhede,
terwyl spesies wat maklik teel, maklik hanteer kan word en kleurvol is of mooi patrone het, in
groter hoeveelhede mee handel gedryf word.
Kalifornië and Florida, in teenstelling met Suid-Afrika, het ‘n hoë aantal goed-gedokumenteerde
gevalle van herpetofauna wat in die natuur vrygestel is. Hierdie introduksies was gebruik om die rol
van verskeie belangrike faktore in die vestiging van populasies te bepaal. Eerstens het ek die rol van
elke faktor apart ondersoek. Ek het verskillende benaderinge vir bioklimatiese model-bou
ondersoek, die akuraatheid van verskillende bronne van distribusiedata getoets en drie metodes om
‘n “climate match score” te bereken, voorgestel. Ek bied ook die eerste toets van Darwin se
naturalisasie-hipotese vir landwerveldiere aan, deur gebruik te maak van twee nuwe filogenieë wat
ek gebou het vir inheemse en ingevoerde reptiele in Kalifornië en Florida. Ek het verder gebruik
gemaak van “boosted regression trees” (BRT) om die relatiewe bydrae van elke faktor tot die
vestigings-potensiaal van spesies te bepaal. Resultate van hierdie BRTs was ingekorporeerd in ‘n
gebruikersvriendelike ontledingstaat wat deur bestuurders, onervare in komplekse
modelboutegnieke, gebruik kan word.
Invoer-hoeveelheid was die faktor wat die sterktste bygedra het tot suksesvolle vestiging. Verder is
spesies met kort jeugperiodes en dié met verlangse familie in streeks-biotas, meer geskik om
suksesvol te vestig. Gemiddelde klimaatooreenstemming en lewensvorm was ook belangrik. Paddas
en akkedisse was die mees waarskynlikste van die herpetofauna groepe om populasies te vestig,
terwyl slange en skilpaaie teen laer tempo’s populasies gevestig het, alhoewel analise van alle
gedokumenteerde gevalle van herpetofauna-invoerings wêreldwyd effens verskillende tendense
toon. Voorspellings wat deur die BRT-model vir onafhangklike data gemaak is was redelik swak,
alhoewel hierdie resultaat onwaarskynlik nie uniek aan die studie is nie, en word gedeeltelik
verduidelik deur die gebrek aan data. Alhoewel talle onsekerhede steeds bestaan, kan dié
verminder word deur geval-tot-geval reëls toe te pas eerder as om vir herpetofauna as ‘n groep te
veralgemeen. Die doel van invoer en potensiële handel-volumes van ‘n spesie, sal die bedreiging
wat die spesie toon, bepaal. Hierdie faktore moet saam met omgewingstoleransie en voorafgaande
sukses van spesies met soortgelyke lewenswyses oorweeg word, om ‘n aanvaarbare en verdedigbare
beraming van vestigingsrisiko te gee. Laastens, word ‘n kort opsomming van die effekte wat
uitheemse herpetofauna mag hê, verskaf.
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