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Insect macroecological patterns along an altitudinal gradient : the Greater Cederberg Biodiversity CorridorBotes, Antoinette 04 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The central goal in macroecology is to determine species diversity patterns across ecological
gradients. Altitudinal and latitudinal patterns in species richness are often assumed to be
analogous. Furthermore, the primary mechanisms underlying richness patterns along these
two gradients might be similar. To date, few studies have tested whether the hypotheses
proposed to explain latitudinal richness variation apply to patterns across altitude. This study
therefore tests several hypotheses proposed to explain patterns in species diversity (i.e.
ambient energy, productivity, area and geometric constraints) and their underlying
mechanisms using altitudinal gradients in epigaeic ant and beetle species richness in the
Greater Cederberg Biodiversity Corridor (GCBC) (Western Cape, South Africa). The study
was conducted across an altitudinal gradient that was laid out from sea level to the top of a
mountain (approximately 2000 m above sea level) and down the other side thereof. First, it
was determined how the ant and beetle assemblages differ between the main vegetation types
included in the transect and which environmental variables might underlie these differences.
Thereafter, the variation in species richness and range size patterns of the two groups was
investigated across the full altitudinal gradient. This is the first study that tests the
applicability of two mid-domain models across such an altitudinal gradient using both
complete and partial assessments. The models explained large proportions of the variance in
range sizes across three domains but the ranges could have been constrained to show peaks in
the middle of the domains due to the way in which the boundaries of the domains were
selected. By contrast, the mid-domain models were not important in explaining species
richness patterns, which suggests that they cannot explain diversity across the gradient. The
species richness patterns of the two groups did not show the predicted mid-altitudinal peak.
Moreover, it was demonstrated that different processes structure ant and tenebrionid
assemblages across the same altitudinal transect. Ant species diversity was highly correlated
to contemporary climatic variables, while historical factors appear to play a more important
role in structuring tenebrionid beetle assemblages. Furthermore, support was found for the
species energy theory in the ant assemblages, as well as for two of its underlying mechanisms,
namely the more individuals hypothesis and the niche position mechanism. These results
suggest that there are likely to be substantial and complex changes to ant assemblages under
the predicted climate change scenarios for the region. Given the crucial role played by this
group in ecosystem functioning (e.g. myrmecochory) it is suggested that these responses are not likely to be a response solely to vegetation changes, but might also precipitate vegetation
changes. This study also forms the basis of a long-term monitoring programme to establish
baseline data for the epigaeic ants and tenebrionids and to monitor changes in these
communities due to climate change. / AFRIKAANSE OPSOMMING: Een van die sentrale idees in makro-ekologie is om die patrone in spesies diversiteit oor
ekologiese gradiënte te ondersoek. Verder word daar aangeneem dat spesie rykheidspatrone
oor hoogte- en breedtegradiënte analoog is aan mekaar en dat die primêre onderliggende
meganismes van die patrone dieselfde kan wees oor hierdie twee gradiënte. Tot dusver het
min studies getoets of die voorgestelde hipoteses wat breedtegradiënte in spesie rykheid
verduidelik van toepassing is op hoogtegradiënte. Hierdie studie toets dus verskeie van
hierdie hipoteses (aanvoelbare temperatuur, produktiwiteit, area en geometriese beperkinge)
en hulle onderliggende meganismes in mier en kewer spesie rykheid in die Groter Cederberg
Biodiversiteits Korridor (GCBK) (Wes Kaap, Suid Afrika). Die studie is uitgevoer oor ‘n
hoogtegradiënt wat vanaf see vlak tot ongeveer 2000 meter bo seevlak en weer aan die ander
kant van die berg af uitgelê is. Eerstens is daar bepaal hoe die mier en kewer diversiteit
verskil tussen die hoof planttipes wat oor die hoogtegradiënt voorgekom het en watter
omgewingsveranderlikes daarvoor verantwoordelik is. Daarna is die variasie in spesie rykheid
en area van verspreiding van die twee groepe ondersoek oor die hele hoogtegradiënt. Hierdie
is die eerste studie wat die toepaslikheid van twee mid-domein modelle oor so ‘n
hoogtegradiënt toets met behulp van volledige en gedeeltelike ondersoeke. Die modelle het
baie van die variasie in area van verspreiding verduidelik oor drie domeine maar die areas van
verspreiding kon beperk gewees het om pieke in die middel van die domeine te vorm as
gevolg van die manier waarop die grense van die domeine gekies is. In teenstelling, het die
modelle nie spesie rykheid verduidelik nie en dus kan hulle nie spesie diversiteit oor hierdie
gradiënt verduidelik nie. Die spesie rykheidspatrone van die twee groepe het nie die verwagte
piek by midhoogte gewys nie. Verder het verskillende prosesse mier en kewer groeperings
oor die hoogtegradiënt gestruktureer. Mier diversiteit was hoogs gekorroleer met
kontemporêre klimaatsveranderlikes, terwyl historiese faktore belangriker was vir die kewers.
Die spesie-energie teorie was ondersteun deur die data, asook die meer individue hipotese en
die nis posisie meganisme. Hierdie resultaat dui daarop dat daar moontlik komplekse
veranderinge in mier groeperings gaan plaasvind soos die klimaat verander. Miere vervul
belangrike ekologiese prosesse in ekosisteme, wat beteken dat die laasgenoemde verandering
nie bloot net gaan plaasvind as gevolg van veranderinge in die plantegroei nie, maar dat hulle
self ook veranderinge kan veroorsaak. Hierdie studie vorm ook die basis van ‘n langtermyn
moniteringsprogram om basislyn data vir hierdie twee ekologies belangrike groepe vas te stel en om veranderinge wat in hierdie gemeenskappe plaasvind, as gevolg van
klimaatsverandering, te monitor.
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Effective conservation of melanistic lizard species in the Greater Cederberg Biodiversity CorridorJanse van Rensburg, Dahne A. 12 1900 (has links)
Thesis (PhD (Zoology))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The Cape Floristic Region (CFR) is a biodiversity hotspot in South Africa, threatened by climate change and various other processes. The Greater Cederberg Biodiversity Corridor (GCBC) is a conservation area incorporating both public and private land, providing a practical and effective solution to conserve biodiversity in the CFR. This area is also home to two of the eight melanistic cordylid lizard species found in south-western South Africa. One of the herpetological conservation targets identified for the GCBC was an understanding of the ecology of melanistic cordylid populations with particular reference to global environmental change.
Most melanistic cordylids occur in cool coastal and montane localities, and it was suggested that melanism has a thermoregulatory function in these species. The first aim of this study was to determine the climatic conditions with which melanistic cordylids are currently associated. Several melanistic cordylid populations showed a distinct association with a high incidence of fog and cloud cover, underscoring the thermal melanism hypothesis, which predicts that melanistic lizards should occur in cool environments. Several other populations, however, did not show such an association.
The next aim was thus to compare habitat use and morphology among 10 melanistic cordylid populations. Individuals of the northern population of Pseudocordylus capensis and the Cordylus peersi population occurred in the warmest environments, used significantly higher rock formations, and had relatively longer limbs than those of other melanistic populations. Having a morphology that allows for flexibility in habitat use, may enable species such as P. capensis to overcome the constraints of melanism in warm environments.
Being melanistic may result in decreased activity times in warm environments. The variation in habitat thermal quality and daily activity patterns of two melanistic cordylid species with different morphologies and habitat preferences, occurring sympatrically, was investigated. During summer, high rocks provided a better thermal quality habitat to P. capensis than small rocks, and P. capensis had a longer activity period than C. oelofseni. This suggests that the thermal opportunities provided by high rock enables P. capensis to increase its activity time.
The impact of terrestrial and aerial predators can help shape body armour in lizards, with those species more exposed to aerial predators being faster and less armoured, and those more exposed to terrestrial predators being more heavily armoured. The degree of body armour in melanistic cordylids and their non-melanistic relatives was investigated. Melanistic members of the cordylus-niger-oelofseni and C. polyzonus clades had less armour than their non-melanistic relatives, supporting the prediction that melanistic cordylids basked more and were more exposed to aerial predators than non-melanistic lizards. An increase in body armour in C. peersi indicated exposure to terrestrial predators, whereas P. capensis had a reduction in body armour, indicating exposure to aerial predators. Little body armour, together with a slender morphology and long limbs, may thus enable this species to move with ease on large boulders and scale vertical surfaces to successfully avoid predators.
Pseudocordylus capensis displayed much greater movement rates during activity than other cordylids. A less sedentary foraging strategy may be a prerequisite for life on large, barren rock surfaces where food availability may be low or not uniformly distributed. Both males and females of this species also had large home ranges, a unique phenomenon for cordylids. Space use of males only overlapped marginally, but extensive overlap among males and females and among females, respectively, was observed.
Due to the constraining effect of climate on the distribution of most melanistic populations, melanistic cordylids should be considered as priority species for conservation. While P. capensis is pre-adapted for survival in warm climates, it is dependent on the availability of suitable habitats. The GCBC would thus play an important role in the conservation of this species’ habitat. / AFRIKAANSE OPSOMMING: Die Kaapse Blommeryk (KBR) is ‘n “biodiversity hotspot” in Suid-Afrika wat deur klimaatsverandering en verskeie ander prosesse bedreig word. Die Groter Cederberg Biodiversiteitskorridor (GCBK) is ’n bewaringsarea wat beide openbare en privaatgrond inkorporeer, en ’n praktiese en effektiewe oplossing tot die bewaring van biodiversiteit in die KBR bied. Twee van die ag melanistiese gordelakkedisse wat in suidwestelike Suid-Afrika aangetref word, kom ook hier voor. Een van die herpetologiese bewaringsdoelwitte vir die GCBK was om insig oor die ekologie van melanistiese gordelakkedis populasies met verwysing na globale omgewingsveranderinge in te win.
Die meeste melanistiese gordelakkedisse kom in koel kus- en berggebiede voor, en daar is voorgestel dat melanisme ‘n termoregulerende funksie by hierdie spesies het. Die eerste doel van die studie was om die huidige klimaatstoestande waarmee melanistiese gordelakkedisse geassosieer word, te bepaal. Verskeie melanistiese gordelakkedis-populasies het ‘n duidelike assosiasie met mis en wolkdekking getoon, wat die termiese melanisme hipotese se voorspelling dat melanistiese akkedisse in koue omgewings moet voorkom, ondersteun. Verskeie ander populasies, het egter nie so ‘n assosiasie getoon nie.
Die volgende doel was om habitatgebruik en morfologie tussen 10 melanistiese gordelakkedispopulasies vergelyk. Individue van die noordelike populasie van Pseudocordylus capensis en Cordylus peersi het in die warmste omgewings voorgekom, het relatief langer ledemate gehad en beduidend hoër rotsformasies as ander melanistiese populasies benut. ’n Morfologie wat buigsame gebruik van die habitat toelaat, kan sommige spesies soos P. capensis in staat stel om die beperkinge van melanisme in ‘n warm omgewing te oorkom.
In warm omgewings mag melanisme tot ’n afname in aktiwiteitstye lei. Variasie in termiese kwaliteit van die habitat en daaglikse aktiwiteitspatrone van twee melanistiese spesies, met verskillende morfologieë en habitatvoorkeure, wat simpatries voorkom is bestudeer. Gedurende somer het hoë rotse ‘n beter termiese kwaliteit habitat aan P. capensis verskaf as die klein rotse, en P. capensis het ‘n langer aktiwiteitsperiode as C. oelofseni gehad. Dit stel voor dat die termiese geleenthede wat deur hoë rotse verskaf word, P. capensis in staat stel om sy aktiwiteitsperiode te verleng.
Die invloed van terrestriële en lugpredatore kan help om liggaamspantser in akkedisse te vorm. Spesies wat hoofsaaklik aan lugpredatore blootgestel is, is vinniger en het minder pantser, terwyl spesies wat hoofsaaklik aan terrestriële predatore blootgestel is, meer pantser het. Die graad van pantser in melanistiese gordelakkedisse en hulle nie-melanistiese naasverwantes is ondersoek. Melanistiese lede van die cordylus-niger-oelofseni en C. polyzonus klades het minder pantser as hulle nie-melanisties naasverwantes gehad, en ondersteun die voorspelling dat melanistiese gordelakkedisse meer in die son gebak het en meer aan lupredatore blootgestel was. ’n Toename in pantser by C. peersi dui op blootstelling aan terrestriële predatore, terwyl P. capensis die minste pantser van alle melanistiese gordelakkedisse het, wat dui op blootstelling aan lugpredatore. Min beskerming, tesame met ‘n lenige morfologie en lang ledemate, mag dus hierdie spesie toelaat om gemaklik oor groot rotse en vertikale oppervlaktes te beweeg en roofdiere suksesvol te vermy.
Pseudocordylus capensis het groter bewegingstempo’s tydens aktiwiteit as ander gordelakkedisse getoon. ‘n Meer beweeglike voedingstrategie mag ook ‘n voorvereiste wees vir ‘n lewe op groot, leë klipoppervlaktes waar voedselbeskikbaarheid dalk laag kan wees en nie eweredig versprei is nie. Beide mannetjies en wyfies het ook groot tuisgebiede gehad, ’n unieke verskynsel by gordelakkedisse. Mannetjies se ruimtes het slegs marginaal oorvleuel, terwyl daar heelwat oorvleueling tussen mannetjies en wyfies se ruimtes was. As gevolg van die beperkende invloed van klimaat op die verspreiding van die meeste melanistiese populasies, moet melanistiese gordelakkedisse as prioriteitspesies vir bewaring beskou word. Terwyl P. capensis pre-aangepas is vir oorlewing in warm klimate, is hierdie spesie afhanklik van die beskikbaarheid van gepaste habitatte. Die GCBK sal dus ’n belangrike rol vervul in die bewaring van die habitat van hierdie spesie.
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Molecular ecology of introduced species in South Africa : the bud gall-forming wasp Trichilogaster acaciaelongifoliae and the Argentine ant Linepithema humileLado, Thomas Francis 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Introduced species displace native species and alter ecological communities, affect
agriculture as well as human health and are economically costly to eradicate. Long term
monitoring of introduced species including the documentation of levels of genetic variation is
therefore of the utmost importance. This study investigated the distribution of genetic variation
in two introduced species distributed across South Africa the bud gall-forming wasp
Trichilogaster acaciaelongifoliae and the Argentine ant Linepithema humile.
The bud gall-forming wasp was introduced into South Africa as a biological control
agent to curb the spread of the invasive long-leaved wattle Acacia longifolia. In addition to the
intended (target) host, the bud gall-forming wasp has also colonised A. floribunda, a noninvasive
ornamental plant. Limited genetic variation was found across South Africa based on
the mitochondrial DNA cytochrome oxidase subunit I (COI) gene. Only 3 haplotypes
characterized 53 individuals collected from 23 localities (nucleotide diversity £k = 0.002 ¡Ó
0.001, haplotype diversity h = 0.482 ¡Ó 0.045). No significant partitioning of genetic variation
was found across South Africa including between host plants (target host = A. longifolia, non
target host = A. floribunda) or between the core (sites of introduction) and edge (naturally
dispersed) sites (ĦST = 0.094, P = 0.288). The limited genetic variation and the absence of
significant genetic structure are congruent with patterns described for many other introduced
species and may suggest that propagule pressure plays only a minor role in species
establishment and spread of the gall-forming wasp across South Africa.
Mitochondrial and nuclear markers were used to describe the distribution of genetic
variation within Argentine ants across their introduced range in South Africa. For the
mitochondrial DNA, low genetic diversity was found for the COI gene with only five haplotypes, separated by single mutational changes, characterizing 101 specimens from 35
localities (nucleotide diversity π = 0.001 ± 0.001, haplotype diversity h = 0.151 ± 0.048).
Notwithstanding the low levels of genetic diversity, mitochondrial variation was significantly
structured (ST = 0.54, P < 0.001) across the landscape. In contrast, microsatellite analyses of
230 ants from 23 localities, employing six polymorphic microsatellite markers, revealed a
relatively high amount of genetic diversity (HE = 0.51 ± 0.22). Significant population structure
was similarly evident (RST = 0.14, P < 0.001) with the localities of Elim2, Porterville2 and
Bloemfontein2 clustering as a distinct population from the remainder of the localities.
Importantly, individuals from these localities also had a unique mitochondrial haplotype and,
when taken with the nuclear results, may indicate the occurrence of more than one introduction
event (and possibly more than one colony) in South Africa. This is further underscored by the
presence of unique microsatellite alleles in these three populations.
In an attempt to establish the source populations for the introduction of Argentine ants
into South Africa, mitochondrial cytochrome b sequences were generated for a subset of ants
representing the two major genetic clades across South Africa. A comparison with the
published data from across the world including the native range of the Argentine ant in South
America grouped Argentine ants from South Africa with three potential source populations
namely Ocampo and Rosario in Argentina and Passo do Lontra in Brazil.
The results of this study underscore the role of human-mediated dispersal in shaping the
levels of genetic variation in both species. Human-mediated dispersal can lead to genetic homogenization across populations. / AFRIKAANSE OPSOMMING: Indringer spesies verplaas of verander ekologiese gemeenskappe, beinvloed landbou
asook menslike gesondheid en is ekonomies duur om te verwyder. Langtermyn monitering van
indringer spesies asook die dokumentasie van genetiese variasie is dus baie belangrik. Hierdie
studie bestudeer die verspreiding van genetiese variasie in twee indringer spesies wat regoor
Suid-Afrika voorkom, naamlik die kroongal-vormende wespe Trichilogaster
acaciaelongifoliae en die Argentynse mier Linepithema humile.
Die kroongal-vormende wesp is na Suid Afrika gebring as biologiese beheeragent om
die verspreiding van indringer lang-blarige wattle Acacia longifolia te beveg. Die kroongalvormende
wespe het sowel die teiken spesies, asook A. floribunda, ‘n nie-indringer
ornamentele plant gekoloniseer. Beperkte genetiese variasie is gevind regoor Suid Afrika
gebasseer op die mitochondriale DNA sitokroom-oksidasie subeenheid I (COI) geen. Slegs 3
haplotipes karakteriseer 53 indiviue van 23 bevolkings (nukleotied diversiteit π = 0.002 ±
0.001, haplotiep diversiteit h = 0.482 ± 0.045). Geen beduinde groepering van genetiese variase
is gevind regoor Suid Afrika nie (ST = 0.094, P = 0.288). Hierdie bevinding geld onafhanklik
van die gasheer plant (teiken gasheer = A. longifolia, nie-teiken gasheer = A. floribunda). Ook
is geen beduidende genetiese groepering gevind tussen die sentrale (plek van inisiele
blootstelling) en perifêre (natuurlik verspreide) lokaliteite nie. Die kleinskaalse genetiese
variase en die afwesigheid van beduidende genetiese struktuur wat hier gevind is, verskil van
die patrone wat voorheen vir baie ander indringer-spesies beskryf is. Dit mag daarop dui dat
‘propagule’ druk slegs ’n klein rol speel in spesies-vestiging en verspreiding van die galvormende
wespe regoor Suid-Afrika. Mitochondriale asook kern merkers is gebruik om die verspreiding van genetiese
variasie in Argentynse miere in Suid Afrika te beskryf. Vir die mitochondriale DNA is lae
genetiese variase gevind vir die COI geen, met slegs 5 haplotipes, gedifferensieer deur enkele
mutasie veranderinge wat 101 monsters van 35 lokaliteite karakteriseer (nukleotied diversiteit
π = 0.001 ± 0.001, haplotiep diversiteit h = 0.151 ± 0.048). Desondanks die lae genetiese
variasie, is gevind dat mitochondriale variasie beduidend gestruktureerd is (ST = 0.54, P <
0.001) oor die landskap. Hierteenoor het mikrosatelliet analises van 230 miere van 23
lokaliteite, deur gebruik te maak van ses polimorfiese mikrosatelliet merkers, ’n relatiewe hoë
hoeveelheid genetiese diversiteit aangedui. Beduidende bevolkingstruktuur was ook gevind
(RST = 0.14, P < 0.001) in die areas Elim2, Porterville2 en Bloemfontein2 wat saam groepeer
as eiesoortige bevolkings vergeleke met die res van die areas. Ook van belang is dat individue
van die areas ’n unieke mitochondriale haplotipe besit, en in kombinasie met die kern resultate,
mag dit die voorkoms van meer as een blootstellingsgeleentheid (en moontlik meer as een
kolonie) in Suid Afrika aandui. Hierdie bevinding word verder beklemtoon deur die
teenwoordigheid van unieke mikrosatelliet allele in die drie bevolkings.
In ‘n poging om die oorsprong van die oorsprong-bevolking vir die blootstelling van
Argentynse miere in Suid Afrika vas te stel, is mitochondriale sitokroom b volgordes
gegenereer vir ’n substel miere wat die twee hoof genetiese klades in Suid Afrika voorstel.
Vergelyking met gepubliseerde data van regoor die wêreld, insluitende die endemiese gebied
van die Argentynse mier in Suid Amerika, het die Argentynse mier van Suid Afrika met drie
potensiele oorsprong-bevolking verbind, naamlik Ocampo en Rosario in Argentina en Passo do Lontra in Brazil.
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Reproductive behaviour and habitat use in the Blue-Eyed Black Lemur (Eulemur flavifrons, Gray, 1867) at the Sahamalaza-Iles Radama National Park, Madagascar.Volampeno, Maria S. N. January 2009 (has links)
The critically endangered blue-eyed black lemur (Eulemur flavifrons) is one the leaststudied
day active lemurs because of the recent rediscovery and limited distribution.
This thesis examined the habitat use, reproductive parameters and the population
viability of the blue-eyed black lemur population at Ankarafa Forest, Sahamalaza-Iles
Radama National Park, Madagascar. The main aim was to gather fundamental
information on the natural history of the blue-eyed black lemur and to propose
conservation approaches for both the species and its habitat. Data were collected over
14 month-period between 2006 and 2008. Six groups of the blue-eyed black lemur
were studied, four of which were collared and two uncollared.
Ankarafa Forest, the largest forest blocks of the Sahamalaza-Iles Radama
National Park, is dominated mainly by Mangifera indica, Garcinia pauciflora,
Sorindeia madagascariensis, Grangeria porosa, Bambou sp. and Mascarenhasia
arborescens species. The forest is vulnerable to degradation by both anthropogenic
activities and abiotic factors. The population density of the blue-eyed black lemur at
Akarafa Forest was estimated to be 97.3 individuals km-², with group size ranging
from 4 to 11 individuals. The home range use and day path length of the blue-eyed
black lemur varied seasonally. The lemur occupied a larger home range in the dry
season than in the wet season. The age of first reproduction in the blue-eyed black
lemurs is about 3 years. They bear offspring seasonally (late August-October), all
adult females in groups bred and females produce singletons offspring. Females were
dominant over males. The sex-ratio at birth was male-biased but not significantly
different from 1:1. Females were the primary caretakers of infants but group members
other than the mother also provided alloparental care. For the first 3 weeks of life,
infants were carried constantly on their mothers’ bellies. Infants developed
independent locomotion and fed on solid food by 10 weeks. Increased probability of
extinction, as shown by population viability models of the blue-eyed black lemur
population, is affected by various of their reproductive parameters. However, these do
not account for changes in their primary habitat forest. The latter is under increased
human pressure and continues to decline in area. Education awareness and community
involvement are required if the habitat and the blue-eyed black lemur are to survive.
Findings of this study serve not only important data to understand the life
history of the blue-eyed black lemur but also suggest conservation approaches for
both the species and its natural habitat. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.
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Evaluation of methods and approaches for surveying savanna invertebrates.Lovell, Saskie Joanne. January 2006 (has links)
The savanna is an important biome, which is under threat from land transformation, and it is therefore a
focus for conservation planning. Yet, the invertebrate fauna of this biome is poorly documented and
hence there is a need to provide baseline data for this component of biodiversity. This project aimed to
provide relevant information that can be used by conservation planners and ecologists, by recommending
a sampling strategy for the collection of specific taxa for savanna invertebrate surveys.
The effectiveness and efficiency of a sampling strategy using passive and active sampling methods was
assessed to provide recommendations for a multi-taxa approach to sampling invertebrates in a savanna
ecosystem. In the collection of data, volunteers assisted and they were evaluated in comparison with
experienced researchers to assess the effectiveness, efficiency and benefits of using volunteers to carry
out multi-taxa invertebrate surveys. In addition, cross-taxon congruency and congruency across
taxonomic levels were assessed between nine invertebrate taxa, to select potential surrogates to reduce
biodiversity survey costs for conservation planning.
Fieldwork was carried out in the Mkhuze Game Reserve (27.67°S:32.27°E, 400km2
), Phinda Private
Game Reserve (27.78°S:32.35°E, 140km2
) and False Bay Park (27.94°S:32.38°E, 25km2
) in north-eastern
Kwazulu-Natal, South Africa. Forty-three different sites were sampled between November 2002 and
March 2005 (summer months). Twenty of these sites were re-sampled across years and in different
months during the summer season, giving 77 sampling events. Fifty-four volunteers recruited by the
Earthwatch Institute assisted in the collection of data.
Lepidoptera, Hymenoptera (Apoidea), Diptera (Asilidae, Bombyliidae), Neuroptera, Odonata, Hemiptera
(Cicadellidae), Coleoptera (Cetoniinae, Scarabaeinae), Orthoptera, Blattodea, Isoptera, Araneae
(Araneidae, Thomisidae, Oxyopidae), Scorpionida, Myriapoda (Diplopoda, Chilopoda), Mollusca and
Annelida were sampled using four active searching methods (transects, tree beating, leaf litter and sweep
sampling) and two passive methods (pan traps and baited traps).
In its entirety, this project sampled 50 558 individuals from 797 invertebrate species and an extensive
database consisting of 33 257 records now exists. A standardised sampling protocol is described for the
effective sampling of multiple invertebrate taxa in a savanna biome and recommendations are made for
improving the efficacy and completeness of invertebrate surveys based on the application of species
accumulation models. Restrictive active searching methods (quadrats) were found to be more effective for
sampling epigaeic invertebrates and should be used in conjunction with leaf litter samples. Flying and
plant-dwelling invertebrates should be sampled using a range of sampling methods which include baited,
malaise and pan traps, active searching along transects and vacuum sampling. I suggest over 75% of the
Lovel/, s.1. - MSc. Thesis i ii
total estimated fauna to be a satisfactory and realistic level of inventory completeness for making valid
comparisons between regions and across sites.
Volunteers sampled lower rates of species accumulation, species richness and unique species when using
timed, active search methods. Nevertheless, volunteers and researchers were shown to perform equally
well when using un-timed, active searching methods. Previous experience or knowledge of scientific
method was beneficial when researchers assessed the perceived usefulness of volunteers to researchers for
carrying out fieldwork. The project experience raised the volunteers' environmental awareness,
knowledge about biodiversity, invertebrates and conservation research, and enabled volunteers to
participate in or design locally relevant conservation based projects on their return home.
Cross-taxon congruencies were observed. However, relationships were weak and potential surrogates
could not be selected. The use of higher taxonomic levels to represent species shows good potential as a
surrogate but only in species-poor genera or families. The use of species density to determine congruency
and select surrogates is likely to produce different results to those produced by community similarity.
Furthermore, when selecting surrogates from congruency assessments an optimal p-value greater than
0.75 should be required. Below this value, the relationship is likely to be weak and if used as a surrogate
misinterpretation may occur. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
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Conservation of the great white pelican (Pelecanus onocrotalus) and the pink-backed pelican (P. rufescens) in south eastern Africa.January 2006 (has links)
Of the seven pelican species found world wide, only the Great White Pelican (Pelecanus onocrotalus) and the Pink-backed Pelican (P. rufescens) are found in Africa. The KwaZulu-Natal province of South Africa supports only one breeding site for each of these species, and both sites represent the southern most breeding colonies for the two species in the eastern region of Africa. These nesting sites fall within the Greater St Lucia Wetland Park, and are afforded a degree of protection, but the same is not true for their foraging and dispersal ranges, and this is a cause for concern. Considerable amounts of data have been collected relating to the status, distribution and breeding efforts of these two species in north eastern KwaZulu-Natal. These data have been collected in a variety of ways by a large number of people. Part of this work represents an attempt to collate and summarise these data to produce an estimation of the status, distribution and breeding success of these species, and to evaluate any trends in their demography. For this south eastern region of Africa I estimated the population for the Great White Pelican to range between 6000 and 9000 individuals, and the Pink-backed Pelican to range between 600 and 900 individuals. Pelicans are highly mobile birds, and this allows them to move considerable distances when they forage, disperse or migrate. They are also long-lived birds with few natural predators. The two pelican species in south eastern Africa have been poorly studied and little is known about their movements, population dynamics and causes of mortality. Habitat change poses a potential threat to pelicans in north eastern KwaZulu-Natal, and habitat loss could drive these species out this region to areas north of South Africa. Much of this north eastern region of KwaZulu-Natal is under threat, mainly through the actions of man. Many areas are naturally unsuitable for pelican foraging, while others are vital to the survival of both species. This study includes an attempt to assess the movements of these two species in south eastern Africa, and to assess the relative importance and condition of the potential pelican habitat in the north eastern KwaZulu-Natal region, focusing particularly on Lake St Lucia and the Pongolo River floodplain. All this is necessary to produce a baseline from which long term predictions of potential pelican species survival can be made. In the absence of documented life tables and environmental variability data, a range of parameters was modelled to generate population viability analyses to simulate possible scenarios. These extinction models show the outcomes of both the deterministic and the stochastic processes. An attempt was also made to identify the factors that impact most severely on the persistence of these two species. The models were most sensitive to variation in survivorship in the first year of life and to the frequency of catastrophes. Changes in these parameters had the greatest effect on extinction risk. In January 2004 Lake St Lucia was reduced to a fraction of its normal capacity as a result of a severe drought in this region of KwaZulu-Natal. After rains in the area the lake level rose and then fluctuated considerably over the next 24 months. During this time the mouth of the estuary into the sea was closed. Great White Pelican numbers and lake levels were monitored throughout this period. This part of the study relates the changes in population numbers to the lake conditions, and highlights the importance of the lake to this avian species. It uses lake levels as a proxy for the conditions of wetlands in the Lake St Lucia region. It also addresses the implications of these relationships to the management strategy of the lake and the conservation of some avifauna. To identify conservation concerns for the Great White and Pink-backed Pelicans it was necessary to generate these baseline estimations. Although much of this information is uncertain for these two species, an attempt has been made here to predict the persistence of these species in north eastern KwaZulu-Natal and to highlight the conservation issues related to their future. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006
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Wildlife rehabilitation in South Africa.January 2009 (has links)
Wildlife rehabilitation, defined as “providing temporary care to injured, ill and orphaned wild animals with the goal of releasing them back into their natural habitat”, developed in response to the increase in human population and urbanisation. Widllife rehabilitation centres developed to deal with casualties from man-made hazards; and because rehabilitation involves human emotions of empathy and compassion, the activity has not tended to be the domain of wildlife specialists, but of concerned members of the public. This has caused concerns for wildlife specialists over the welfare of animals being rehabilitated, because making decisions based on emotions may result in an animal being kept alive under unethical conditions, instead of being euthansed. Furthermore, there may be negative impacts on conservation, as it could divert money away from habitat protection and may place wild populations at risk from disease and genetic pollution. This dichotomy in opinion is most often seen between rehabilitators, who focus on the individual animal, and government wildlife officials, who grant them permits, and who focus on the security of entire communities. Although the value of wildlife rehabilitation cannot be underestimated, in terms of its service to wildlife and the public, there is a need to evaluate whether wildlife rehabilitation may result in more rather than less animal suffering and have a detrimental impact on the existing wild populations. I thus set out to determine the efficacy of wildlife rehabilitation, particularly in South Africa. In the first assessment of rehabilitation centres in South Africa, 65% known centres (n = 63) from all nine provinces returned questionnaires. Several thousand injured, diseased and orphaned animals pass through these centres each year, clearly showing the need for rehabilitation centres in South Africa. However, due to lack of scientific research on the efficacy of rehabilitation methods of care and release, and minimal post-release monitoring, I found that experience and intuition drove most rehabilitation practices. Additionally, because personnel from most centres cited lack of finance as a main impediment to the goal of rehabilitation, the result of rehabilitation may include negative affects on individual animal welfare and survival, as well as on conservation efforts for wildlife communities. Thus, I suggested wildlife rehabilitation be centralised to a provincial or national government. Furthermore, I suggested that guidelines of minimum standards should be developed in consultation with experienced rehabilitators, veterinarians and conservation scientists; to be enforced by trained and dedicated conservation officials. To gain further insight into the need for wildlife rehabilitation in a community in South Africa, I decided to examine four-years of intake records from a large rehabilitation centre in the KwaZulu-Natal Province for trends. Animal intake rate was high (2701 ± 94 per annum). Most of the intake (90%) was birds, with few mammals (8%) and reptiles (2%), and most of these were of locally common species (eg doves, pigeons). This reflects the findings of other studies, namely that species living in close association with humans are the most frequently admitted to rehabilitation centres. In total, most of the animals admitted (43%) were juveniles, which were assumed to be abandoned or orphaned. The implications of then rehabilitating these juveniles, which were largely uninjured, is whether humans should be interfering with nature if the cause was not human-related; can each juvenile (especially in these large numbers) be adequately prepared to survive and thrive when released into the wild; and is there space in the environment for them, without causing harm to others already in the environment. I suggest that the large numbers of animals currently being admitted to the centre may be reduced, possibly through increased public education particularly to leave uninjured juveniles in the wild. Furthermore, improvements in the centre’s recording system may allow for use in funding requests and for various research opportunities. There is a general lack of post-release monitoring in wildlife rehabilitation, and the IUCN advises that confiscated and orphaned animals should be euthanased or placed in life-time captivity. I thus decided to document the post-release fate of rehabilitated vervet monkeys and leopard tortoises, two species commonly admitted to a rehabilitation centre, and rock hyrax (Procavia capensis), as a further case study, even though individuals were not from a rehabilitation centre. Success of releasing rehabilitated animals cannot be judged on whether it results in a self-sustaining population, as in reintroductions, as it is to improve the welfare of that particular animal, independent of its species’ status. Survival is thus the most basic indicator of a successful rehabilitation release. Other aspects, such as behaving similarly to a wild animal, are additional success factors, as they likely influence survival. Although after one year post-release, the two troops (T1 = 35, T2 = 24) of vervet monkeys (including an infant) survived, were independent of human food provision and companionship, had established in an area, and had births in the breeding season following release; low known survival (T1 = 11%, T2 = 50%) make it difficult to designate these releases as successful. However, it was clear that the two groups of rock hyrax released were not successful. The group of rock hyrax that had previously been in captivity for 16 months (n = 17) did not have site fidelity after release, and after three months could not be found. All wild rock hyrax (n = 9), except one whose fate is unknown, were found dead, mostly predated, within 18 days. The release likely failed due to predation. For both vervet monkeys and rock hyrax, a lack of social cohesion was suggested as causing the group to dissolve or split upon release, which in turn would increase their vulnerability to predation. Recommendations are provided for considerations in future releases of captive vervet monkeys and rock hyrax. Movements of two groups of tortoises (ten and seven individuals) released at two different sites were monitored over a year, using radio-telemetry. In total, one tortoise was returned to captivity because of disease, four were killed intentionally or accidentally by humans, three others died due to a combination of disease, starvation and/or dehydration, and the fate of six were unknown. Since only two out of seven tortoises survived 13 months after release and only one out of ten tortoises were known to have survived 25 months after release, rehabilitated leopard tortoises were not successfully released into the wild. Recommendations to improve the success of future releases are provided. The occurrence of disease in the tortoise release was a worrying result, and must be addressed before any further releases are allowed. To summarise, there is a dichotomy between wildlife rehabilitation and conservation throughout the world, but this study highlighted the situation in South Africa. The IUCN guidelines for the reintroduction, introduction and supplementation of animals make it clear that there are many threats to the individual animal, to the release environment and to the conservation of species when transporting and releasing animals, especially if they had been in captivity. I believe that I have presented enough evidence in the thesis to suggest that wildlife rehabilitation may result in negative consequences to the welfare of the individual being rehabilitated and to the wild conspecifics or to other species in the release site. I suggest that wildlife rehabilitation needs to move away from being an emotional-based “animal-rights” organisation, to being objectively managed, such that no harm is caused to conservation by these efforts. This may require them to change their constitution so they are aligned with the IUCN guidelines, where more consideration is given to the possible risks involved in releasing animals. However, the applicability of the IUCN guidelines will vary slightly according to the species and situation, and they require input from the local conservation authorities (as was the case in the studies documented in this thesis). I suggest that the public be educated as to the risks that wildlife rehabilitated animals can pose to the safety of the environment as a whole, and that rehabilitated animals do not necessarily survive or thrive in the wild when released, and thus they have to understand that rehabilitation centres will sometimes have to prioritise casualties for treatment, and euthanase exotic species. In conclusion, implementing further research in ensuring long-term post-release survival of rehabilitated animals; developing and enforcing practical guidelines/minimum standards by dedicated and qualified governmental wildlife conservation officials; and having examinations in order to qualify as a wildlife rehabilitator, will ensure humans are “making amends” instead of having an additional negative impact on conservation and animal welfare. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009
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Bird community ecology and composition in afrotemperate forests of the Drakensberg Mountains, South Africa.January 2009 (has links)
Recent research has emphasized the importance of understanding the consequences of species loss, not just for biodiversity per se, but also for ecosystem resilience and functioning. Firstly, a baseline analysis of the effects of a naturally patchy landscape on avian community composition and resilience in a high altitude Afrotemperate forest landscape in South Africa is presented. Bird data from a point count survey of 706 counts at 31 forest sites was used to test whether taxonomic species diversity, functional species richness and density of birds provide insight into community resilience in this historically patchy ecosystem. Bird species richness of forest patches ranged from 17 to 38, with a total species richness of 50. Density was slightly but negatively related to both area and species richness. That density compensation is occurring in these Afrotemperate forests suggests a level of resilience in this system. Following on from this, cumulative species-area and function-area graphs were derived to quantify the loss of forest area or taxonomic bird species richness that this landscape may potentially sustain before ecosystem functioning is negatively affected. The concept that species’ patterns of distribution, abundance and coexistence are the result of local ecological processes has recently been challenged by evidence that regionalscale processes are equally instrumental in shaping local community composition. The historically and naturally fragmented Afrotemperate forests of the uKhahlamba– Drakensberg Park, South Africa, offer an interesting test case. In this study the relative effects of local and regional-scale processes on species assemblages in a naturally patchy forest system were investigated. By employing species-area and species-isolation relationships, and nested subset analyses, we showed that isolation (regional-scale process) had a greater effect on bird species richness and composition than area (local-scale process), though the species-area relationship was significant. Using generalized linear models and an information-theoretic approach to model selection, patch area, the size of the regional species pool as well as the distance to the nearest Eastern Mistbelt forest were all influential in determining local bird species richness in these montane forests. Thus, localities are regionally enriched within the constraints on species occupancy provided by the available habitat. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.
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Comparative aspects of the thermal biology of African and Australian parrots.Burton, Stephen Leslie. January 2006 (has links)
Deserticolous birds inhabit an environment characterised by high ambient temperatures and low
rainfall that has low primary productivity. The combination of these factors may lead to the
evolution of adaptations that minimise food and water requirements. One physiological
adaptation that has been found in many deserticolous birds is the reduction of basal metabolic
rate (BMR).
I measured metabolic rate in the laboratory using four species of African lovebirds
(Agapornis) , and four species of Australian grass parakeets (one Neopsephotus and three
Neophema), all similar in body mass. Tests for differences between groups were carried out
using both conventional and phylogenetically independent methods. The BMRs of the lovebird
and grass parakeet species were not statistically correlated with habitat type. These results
confirm the findings of previous studies on the effect of desert conditions on the BMR of parrots.
I also found no significant differences in BMR between the species assemblages from different
continents. The lack of significant differences in BMR between deserticolous and nondeserticolous
parrots supports the idea that birds are "ex-adapted" to living in desert
environments. I suggest that the results may have been affected by phenotypic plasticity in BMR,
as recent evidence has shown that the scaling exponent of BMR differs between captive-raised
and wild-caught birds.
To elucidate the effect of origin (captive-raised vs. wild-caught) on the BMR of birds
used in this study a large scale analysis of bird BMR data was undertaken. BMR and body mass
data for 242 species of birds were obtained from the literature, this study, and unpublished data
from various sources. A phylogeny was constructed using molecular and morphological
phylogenies from the literature, and analysed using conventional and phylogenetically
independent methods. The conventional analysis found significant differences in the scaling
exponents of BMR of captive-raised and wild-caught birds. However the phylogenetically
independent method showed non-significant differences between these two groups. Conventional
analysis of differences between parrots and all other birds yielded significant differences
between these two groups, with parrots having significantly higher BMRs than other birds.
Again the phylogenetically independent analysis found non-significant differences between these
VII
two groups. A test of homogeneity of variance between these two groups found significant
differences between the variances ofthe two groups, probably due to disparity in sample size and
range of body sizes. The conventional and phylogenetically independent tests for differences
between captive-raised and wild-caught parrots yielded non-significant results, suggesting that
the parrots are not subject to the phenotypic adjustments postulated for all other birds.
The lack of significant differences between captive-raised and wild-caught parrots
suggests that the analyses of differing habitat type for African and Australian parrots is indeed
valid. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
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An investigation to determine the critical habitat requirements of the breeding Blue Swallow Hirundo atrocaerulea Sundevall.Wakelin, James. January 2006 (has links)
This study investigated the critical habitat requirements of breeding Blue
Swallows Hirundo atrocaerulea Sundevall, in KwaZulu-Natal, South Africa.
Blue Swallows, as a 'flagship species' of the KwaZulu-Natal endemic Mistbelt
Grassland, were tagged and radio-tracked to obtain positional data to determine
their habitat use while breeding. This information was correlated to the type
and nature of the habitat used and to the nature of the land cover to determine
the likely impact of habitat transformation and fragmentation on breeding Blue
Swallows. Insect type and abundance was assessed in five surrounding habitat
types using Malaise insect traps and the findings correlated to Blue Swallow
habitat usage. Data on environmental variables were collected using HOBO®
sensors and the findings related to insect type and abundance within each
habitat type. A comparative investigation was undertaken using temperature
and humidity data obtained below-ground at a Blue Swallow nest site and
compared to temperature and humidity findings from above-ground.
Preliminary investigations were also made into the breeding system used by the
Blue Swallow using unique wing markings to estimate the number of individuals
involved at a single active nest.
Overall, wetland and grassland were first choice habitats a function of the
increased individual insect mass in these habitats. Tea plantations were the
next most important habitat type and timber plantations were avoided.
Furthermore, it was shown that the Blue Swallow is a species that favours
ecotones as preferential forage zones, particularly the ecotone between wetland
and grassland. Malaise insect traps were effective in gathering suitable insect
samples for analysis, revealing that significant differences occur in insect order,
number and mass between habitat types. The most significant finding is that
average insect mass per order, which was correlated closely to habitat type,
matches the order of positive habitat type selection by the Blue Swallow. These
findings were statistically significant and it is suggested that this correlation is the
main reason behind the habitat selection by Blue Swallows. This study found a
clear indication that insect numbers and mass, in grassland and wetland,
increase with an increase in temperature and decrease with a decrease in
average temperature. Clear trends were obvious during long periods of either
cold or dry weather which .negatively influenced insect abundance and
potentially, in turn, Blue Swallow well-being. The underground cavity used as
the nesting site by Blue Swallows, experiences a greatly moderated climate in
terms of the range of environmental factors compared with those experienced
above-ground. This climate moderation is thought to be a clear advantage for
the well-being of the Blue Swallow eggs and nestlings.
Through the use of radio-tracking, visual markers and video footage it was clear
that Blue Swallows breed with a number of adult birds at one nest. The
recorded average sex ratio was 1(; : 3<;2, however, the need remains to
elucidate the co-operative breeding system used by the Blue Swallow.
In conclusion, the findings of this work present recommendations and
suggestions on habitat management, offer insight into future research
opportunities, and suggest strong conservation action for the species. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
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