Spelling suggestions: "subject:"thesisideology."" "subject:"thesociology.""
41 |
The freshwater Diaptomidae (Calanoida : Copepoda) of Southern Africa.Rayner, Nancy Alison. 06 June 2014 (has links)
Freshwater copepod taxonomy has been neglected
in southern Africa for more than 50 years and this has
placed a constraint on research on the biology and ecology
of this important component of the freshwater invertebrate
fauna. In this review of the calanoid family Diaptomidae
of southern Africa, keys to the freshwater families, the
African genera and southern African species are presented
as well as diagnoses of the family Diaptomidae and the
subfamilies Paradiaptominae and Diaptominae. The genus
Lovenula has been revised. All available information on
each species has been collated. This includes illustrations
of the most important identifying characters, synonymies,
a record of material examined and a map of distribution.
The discovery of 11 new species, four Paradiaptomus,
two, Metadiaptomus and five Tropodiaptomus, indicates
that the diaptomid fauna of southern Africa is more diverse
than was previously envisaged. Biogeography and evolution
of the group is discussed with reference to vicariance,
dispersal and palaeoenvironments of the African continent.
The Paradiaptominae (Lovenula, Paradiaptomus and Metadiaptomus)
are endemic to Africa, while the Diaptominae have
one endemic African genus Thermodiaptomus and the other,
Tropodiaptomus, is not limited to the African continent.
The latter genus has speciated throughout the warmer regions of Africa, with more than 30 described species.
Additional collections from isolated regions will, without
doubt, substantially increase this number. Included in
the account is a glossary of copepod terminology, an explanation
of local limnological terms in current use, and a
gazetteer. Biographical information on the pioneers of
copepod research in southern Africa is included. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1990.
|
42 |
An autecological study of bushbuck and common duiker in relation to forest management.Allen-Rowlandson, Timothy Simon. January 1986 (has links)
Frequent reports of damage caused by bushbuck and common
duiker browsing on commercially important timber seedlings,
and an interest in the potential and feasibility of hunting
these two species on State land were the primary factors
responsible for the Directorate of Forestry's motivation of
this study. The study area at Weza State Forest comprised
approximately 21 000 ha of plantations, grasslands and
indigenous forests which were considered representative of
timbered areas throughout the Natal midlands.
Several methods of age determination were investigated
and these findings permitted assessments of growth, fecundity
and population structure. The physiological condition of
both antelope species was examined in relation to age, sex,
reproduction and management strategies, and the results
discussed in conjunction with mortality patterns. Principal
foods of both bushbuck and duiker were determined from rumen
analyses while 112 marked animals were regularly monitored to
facilitate assessments of habitat selection and levels of
spatial and social organisation.
of these largely solitary and
Estimates of the abundance
nocturnal antelope were
influenced by local movements in response to the availability
of food and cover which varied seasonally and also fluctuated
dramatically with forest succession and timber management
activities.
Although bushbuck and duiker bred throughout the year
and had almost identical rates of reproductive performance,
different factors were responsible in limiting the sizes of
these two populations. All the available evidence gathered
in this study indicated that food resources during winter and
early spring were inadequate for bushbuck, particularly in
1983 when 33% of the marked population died from starvation
and/or exposure. Notable differences in forage utilization
and habitat selection inferred little interspecific
competition at this time of the year.
In contrast,
territorial duiker appeared to be susceptible to highly
localised habitat modifications (including the availability of food and cover) which occurred throughout the year and
resulted from silvicultural and timber harvesting practices.
Rumen analyses and quantitative damage assessment
surveys revealed that browsing on timber seedlings was
usually confined to localised areas during the winter months
and was much less severe than had been originally suggested.
Conifers were regarded as a starvati~n food and methods of
reducing damage to these young trees were recommended for
potential problem areas.
Both antelope species were considered overabundant at
Weza and recommendations for the future management of these
populations included the limited utilization of surplus
animals, by sport hunting on a sustained yield basis, and
methods of manipulating and improving forest habitats. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.
|
43 |
Social structure and spatial-use in a group-living lizard, Cordylus cataphractusEffenberger, Etienne 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: There is overwhelming evidence that the Armadillo Lizard, Cordylus
cataphractus, forms permanent aggregations, and that termites are
possibly the most important component of the diet of this species. In
addition, the spinose morphology and defensive tail-biting behaviour
displayed by this lizard species strongly imply that individuals move away
from the crevice, where they are more vulnerable to predation. Therefore
the aim of this part of the study was to investigate whether C.
cataphractus harvest termites at the termite foraging ports and to discuss
the likely ecological implications of termitophagy for this species. A
quadrate at the Graafwater study site, including several crevices housing
C. cataphractus groups, was measured out. All the foraging ports of the
subterranean harvester termite (Microhodotermes viator) present in the
quadrate, were located and their positions recorded in respect to the
distance from the nearest crevice housing lizards. The presence of C.
cataphractus tracks at the foraging ports was used to verify whether
individuals visited specific termite foraging ports. Tracks were found at
foraging ports located at an average distance of 6.1 m, but were also
located at foraging ports up to 20 m from the nearest crevice. The results
strongly support the hypothesis that C. cataphractus individuals move
away from the crevice to feed on termites. Termitophagy and the heavy
armature of C. cataphractus appear to be key factors in the group-living
behaviour of this species. Termitophagy allows individuals to live in
groups as competition for food at the home crevice will be limited. Theheavy armature of C. cataphractus renders it clumsy and slow-moving,
compared to other cordylids. Group-living will, however, eliminate juvenile
dispersal and mate-searching excursions, activities which, in the light of
the heavy morphology of the species, may result in high predation impact.
The global objective of the study was to investigate social structure and
space-use in Cordylus cataphractus. For the correct interpretation of data
on the latter, it was necessary to first establish an ethogram for the study
animal. Members of a multi-male group located at the Graafwater site,
including all age-sex classes, were observed in the field by telescope, for a
total of 102 hours. All individuals were observed to predominantly display
maintenance behavioural act systems, however, agonistic act systems
were also observed. Aggression levels were determined for the respective
agonistic behavioural acts observed. Males were highly aggressive and
displayed the most aggression (67.42 %). Females and sub-adults
displayed aggression for 34.97 % and 37.75 % of the total observation
time, respectively. Juveniles did not display aggression at all. Mating
behaviour was also observed and described. An ethogram was thus
established for the first time for C. cataphractus, and was compared to the
ethograms available for a few other cordylids.
The spatial distribution of individuals within a population has an
important impact on the social structure that ensues. Living in a group
imposes several pressures on the individual and competition for mates is
one. The main aim of the study was to determine the space-use of all theindividuals included in a multi-male Cordylus cataphractus group (n = 55),
to elaborate on the mating system. Specific focus was on the adult males
and females of the multi-male group, because, ultimately, the manner in
which individuals, particularly the adult males and females, utilise space,
determines the mating system. The mating system is an important aspect
of social structure. A two-dimensional grid pattern was delineated at a
free-living, multi-male group’s crevice, situated at the Graafwater study
site, to be able to plot the position of each individual during observations.
All marked individuals, that were visible, were scanned through a
telescope and their respective positions were recorded at 30-minute
intervals. Arcview 3.2 Geographical Information Software was used to
create a computerised model replicate of the two-dimensional grid pattern
at the crevice, and to graphically depict the recorded positions for each
individual. The space-use of males overlapped greatly with the space-use
of females (66.12 ± 31.81 %), but a 0 % overlap in space-use was observed
among adult males. The space-use of sub-adults and juveniles overlapped
highly among one another, as well as with the space-use of adult males
and females. The results showed conclusively that adult male C.
cataphractus are territorial, defending specific sites at the crevice. The
territory of each male included in the multi-male group incorporated at
least one female. The space-use of several females incorporated the
space-use of two or more males. Males were observed to mate with one or
more females, and one female was observed to mate with two different
males on more than one occasion. Thus the evidence strongly suggests that C. cataphractus males display typical territorial polygyny whereas
females may be promiscuous. / AFRIKAANSE OPSOMMING: Daar is oorweldigende bewyse dat die pantsergordelakkedis, Cordylus
cataphractus, permanent in groepe bly en dat termiete waarskynlik die
belangrikste komponent in die dieet van hierdie spesie is. Die stekelrige
morfologie en die stert-byt beskermingsgedrag is verder sterk aanduidings
dat hierdie akkedisse tyd weg van hul klipskeure spandeer waar hulle
meer gevoelig vir predasie is. Die doelwit van die eerste deel van die studie
was om te bepaal of C. cataphractus termiete by die voedingspoorte van die
termietneste oes en verder ook om die moontlike ekologiese implikasies
wat termitofagie vir die spesie inhou, te bespreek. ‘n Kwadraat was by die
Graafwater studielokaliteit uitgemeet om verskeie akkedisgroepe in te
sluit. Al die voedingspoorte van die suidelike grasdraer termiet
(Microhodotermes viator) binne die kwadraat is gevind en die afstande na
die naaste klipskeur wat akkedisse huisves, is vir elke voedingspoort
bepaal. Die teenwoordigheid van C. cataphractus spore in die sand by die
voedingspoorte was gebruik om besoeke aan spesifieke voedingspoorte te
bevestig. Spore is by voedingspoorte gemiddeld 6.1 m vanaf die naaste
akkedisgroep gevind, maar tot so ver as 20 m vanaf die naaste
akkedisgroep. Die resultate verleen sterk ondersteuning vir die hipotese
dat C. cataphractus individue op termiete weg van hul klipskeur af voed.
Termitofagie en die swaar pantser van C. cataphractus is waarskynlik
sleutelfaktore in die groeplewe-gedrag van die spesie. Termitofagie laat
groeplewe toe omdat kompetisie vir voedsel by die klipskeur beperk sal
wees. Die swaar pantser van C. cataphractus het tot gevolg dat die spesie lomp en stadig is in vergelyking met ander gordelakkedisse. Groeplewe sal
egter natale spreiding en maatsoek-ekskursies, aktiwiteite wat in die lig
van die lompheid van die spesie swaar predasie impak tot gevolg kan hê,
uitskakel.
Die oorhoofse doelwit van die studie was om die sosiale struktuur en
spesifiek ruimtebenutting by C. cataphractus te ondersoek. Vir korrekte
interpretasie van data oor lg. was dit egter eers nodig om ‘n etogram vir die
studiedier saam te stel. Lede van ‘n multi-mannetjie groep, wat alle
ouderdomsgrootte klasse ingesluit het, is by die Graafwater
studielokaliteit m.b.v. ‘n teleskoop vir ‘n totaal van 102 uur dopgehou. Al
die individue in die groep het oorwegend instandhoudingshandelingsisteme
vertoon, alhoewel agonistiese handelingsisteme ook
vertoon is. Aggressievlakke is vir die verskeie agonistiese
gedragshandelings bepaal. Mannetjies was hoogs aggressief en het die
meeste aggressie vertoon (67.42 %). Wyfies en subvolwassenes het
aggressie vir 34.97 % en 37.75 % van die totale observasietyd
respektiewelik getoon. Jong individue het geen aggressie getoon nie.
Paringsgedrag was ook waargeneem en beskryf. ‘n Etogram is dus vir die
eerste keer vir C. cataphractus opgestel en is ook vergelyk met etogramme
van ander gordelakkedisse.
Die ruimtelike verspreiding van individue binne ‘n populasie het ‘n
belangrike invloed op die sosiale struktuur wat daaruit voortvloei. Om in
‘n groep te lewe, plaas verskeie drukke op die individue binne die groep en kompetisie vir maats is een hiervan. The hoofdoelwit van die studie was
om die ruimtebenutting van al die individue binne ‘n multi-mannetjie
groep van C. cataphractus (n = 55) te bepaal en om die paringsisteem in so
‘n groep te ondersoek. Die spesifieke fokus was op die volwasse mannetjies
en wyfies, omdat die paringsisteem deur die wyse waarop volwasse
individue ruimte benut, bepaal word. Die studie is by die Graafwater
studielokaliteit gedoen. Die oppervlak buite ‘n klipskeur wat deur ‘n
multi-mannetjie groep bewoon word is opgedeel in sektore om die
kartering van die posisies van die individue tydens observasietye moontlik
te maak. Al die individue is vooraf met verfkodes langs die kant van die
kop gemerk en op gegewe observasiedae is individuele posisies elke 30
min aangeteken. Arcview 3.2 Geographical Information Software was
gebruik om ‘n tweedimensionele, gerekenariseerde replikaat van die
klipskeur en onmiddelike omgewing te skep en om die waargenome
posisies van individue grafies voor te stel. Die ruimtebenutting van
mannetjies het grootliks met dié van wyfies oorvleuel, terwyl zero
oorvleueling tussen mannetjies waargeneem is. Ruimtebenutting van
subvolwasse en jong individue het ook grootliks onderling oorvleuel en ook
met dié van volwasse mannetjies en wyfies. Die resultate toon duidelik
aan dat volwasse mannetjies territoriaal is en dat spesifieke standplase
rondom die klipskeur verdedig word. Die territorium van elke volwasse
mannetjie het of ‘n gedeelte of die hele ruimtebenutting van ten minste een
volwasse wyfie ingesluit. Ruimbenutting van verskeie wyfies het met dié
van twee of selfs meer mannetjies oorvleuel. Mannetjies is waargeneem om
met meer as een wyfie te paar en ten minste een wyfie het met meer as een mannetjie gepaar. Die resultate dui dus sterk daarop dat C. cataphractus
mannetjies tipies terrotoriale poligenie vertoon terwyl wyfies weer
promisku is.
|
44 |
Meerkat latrines : cooperation, competition and discriminationJordan, Neil R. (Neil Robert) 12 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Many territorial carnivores deposit faeces and other scent-marks at specific latrine
sites, and their role in territorial defence is often assumed. However, recent empirical
and theoretical work suggests that ultimate explanations of territoriality differ
between the sexes. In this thesis, I investigate patterns of latrine-use in cooperatively
breeding meerkats, Suricata suricatta. Meerkats exhibit high reproductive skew, and
in such societies an individual’s optimal investment in territory defence and intruder
deterrence will depend not only on its sex, but also its breeding status within the
group. The spatial and temporal distribution of meerkat latrines reflects the diversity
in intruder type. Shared latrine sites between neighbouring groups facilitate costeffective
monitoring of predictable intruders and surrounding land tenure. In contrast,
intruding transient groups and prospecting males are effectively intercepted by
latrines concentrated in the core of the territories, close to refuges. This represents the
optimal strategy, as meerkat territories are too large to allow effective scent-marking
around their entire peripheries, and these intruders travel between refuges during
intrusions. Temporal patterns of latrine-use suggest their importance in mate-defence.
Latrine-use was correlated with encounters with prospecting males and oestrous
periods of resident females, and reached a peak coinciding with the season of elevated
dispersal and take-over events. Additionally, rather than cooperatively contributing to
territorial defence, individuals participated selfishly at latrines. Males preferentially
over-marked female scent-marks and scent-marked at significantly greater rates than
females, which resulted in male-biased latrines that were unrepresentative of group
composition. Although all individuals investigated female scent-marks for
significantly longer than male scent-marks, females invested most, suggesting that
intra-group monitoring is an important aspect of latrine visits for females. The deleterious effects of close inbreeding are well known, but regular dispersal in both
sexes, and long dominance tenure, result in unfamiliar siblings having a high
probability of encountering one another post-dispersal. As latrines are implicated in
mate-defence, olfactory assessment of factors affecting mating decisions might be
expected, but although individuals do recognise foreign faeces, discrimination does
not appear to occur on the basis of kinship. Together, these findings have broad
implications for our understanding of individual variation and sex differences in
scent-marking behaviour and territoriality. / AFRIKAANSE OPSOMMING: Baie territoriale karnivore deponeer faeces en ander reukmerke by spesifieke latrines
en die latrines se rol in gebiedsverdediging word dikwels aangeneem. Onlangse
empiriese en teoretiese werk stel egter voor dat die uiteindelike verduidelikings van
territorialiteit verskil tussen die geslagte. In hierdie tesis ondersoek ek patrone van
latrine-gebruik in samewerkend-broeiende meerkaaie (Suricata suricatta). Meerkaaie
toon ‘n hoë graad van voorkeuraanwas en in sulke gemeenskappe sal ‘n individu se
optimale belegging in gebiedsverdediging en indringer-verjaging nie net van sy/haar
geslag afhang nie, maar ook van sy/ haar teelstatus in die groep. Die ruimtelike en
temporale verspreiding van meerkat latrines weerspieël die verskeidenheid van
indringertipes. Gedeelde latrine areas tussen naburige groepe help die kosteeffektiewe
bestekopname van voorspelbare indringers en omringende landsbesetting
aan. In kontras hiermee word tydelike groepe en geleentheidsoekende mannetjies
effektiewelik voorgekeer deur latrines wat gekonsentreer is in gebiedskerne, naby aan
skuilplekke. Dit verteenwoordig die optimale strategie, aangesien meerkat
territoriums te groot is om effektiewe reukmerking van die hele grens toe te laat, en
synde hierdie indringers tussen skuilplekke reis tydens invalle. Tydspatrone van
latrine-gebruik dui die belangrikheid hiervan in paarmaat-beskerming aan. Latrinegebruik
korreleer met ontmoetings met geleentheidsoekende mannetjies en die oestrus
tydperk van inwonende wyfies, en bereik ‘n toppunt tydens die seisoen van verhoogde
verspreiding en oornames. Ook sal individue selfsugtig deelneem by latrines eerder as
om samewerkend by te dra tot gebiedsverdediging. Mannetjies verkies om vroulike
reukmerke oor te merk en reukmerk teen ‘n beduidend hoër koers as wyfies, wat lei
tot mannetjie-geneigde latrines wat nie verteenwoordigend is van die
groepsamestelling nie. Alhoewel alle individue vroulike reukmerke beduidend langer as manlike reukmerke ondersoek, belê wyfies die meeste, wat daarop dui dat intragroep
monitering ‘n belangrike aspek van latrine-besoeke is vir wyfies. Die nadelige
effekte van sterk inteling is goed bekend, maar gereelde verspreiding in beide geslagte
en lang dominante posisiehouding lei daartoe dat daar ‘n groot kans is vir onbekende
nabye familielede om mekaar te ontmoet na verspreiding. Aangesien latrines ‘n rol
speel in paarmaat-verdediging kan dit verwag word dat daar olfaktoriese beoordeling
sal wees van faktore wat paringsbesluite beïnvloed, maar hoewel individue wel
vreemdelinge se faeces herken, toon hulle geen onderskeidingsvermoë gebaseer op
verwantskap nie. Saamgevoeg, het hierdie bevindinge wye implikasies vir ons begrip
van individuele variasie en geslagsverskille in reukmerk-gedrag en terriorialiteit.
|
45 |
Comparative ecology and behaviour of Chamaeleo pumilus pumilus (Gmelin) and C. namaquensis A. Smith (Sauria: Chamaeleonidae)Burrage, Bryan Ronald 01 1900 (has links)
Thesis (PhD)--Stellenbosch University, 1972. / ENGLISH ABSTRACT: See item for full text
|
46 |
Rattini (Rodentia, Murinae) species relationships and involvement as reservoirs for Scrub Typhus : a comparative molecular cytogenetic gene expression approachBadenhorst, Daleen 12 1900 (has links)
Thesis (PhD (Botany and Zoology))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The Rattus sensu lato complex, which harbours the important biomedical model species
Rattus norvegicus, represents a group of rodents that are of clinical, agricultural and
epidemiological importance. This study presents a comprehensive comparative molecular
cytogenetic investigation of this complex. Karyotypes of 11 Rattus s. l. species and
Hapalomys delacouri were analysed using conventional cytogenetic techniques. These data
suggest that, contrary to previous claims, the usefulness of karyotypes for identifying these
Asian murid species is limited, as few species-specific chromosomal characters could be
identified. In order to understand the events that shaped the morphology and composition of
the extant karyotypes, nine out of the 11 Rattus s. l. species were analysed by chromosome
painting. This allowed the detection of a rare convergent sex-autosome translocation present
in H. delacouri and B. savilei, whose establishment is hypothesised to have been favoured by
the presence of interstitial heterochromatic blocks (IHBs) at the boundaries of the
translocated segments. These results indicate that Rattus s. l. is characterised by slow to
moderate rates of chromosome evolution in contrast to the extensive chromosome
restructuring identified in most other murid rodents. Based on these data the first
comprehensive putative Rattini ancestral karyotype was constructed. Their integration with
published comparative maps enabled a revision of the previously postulated ancestral murid
karyotype. BAC-mapping unequivocally demonstrated that the widely reported
polymorphisms affecting chromosome pairs 1, 12 and 13 in the Rattus karyotypes are due to
pericentric inversions. The analysis of genomic features, such as telomeres, Ag-NORs and
satellite DNA suggest a constrained pattern of chromosome evolution. The investigated rat
satellite I DNA family appears to be taxon (Rattus) specific, and of recent origin (consistent
with a feedback model of satellite evolution).
The comparative nature of the study led to the further analysis of the species within Rattus s.
l. complex and their possible involvement as reservoirs of scrub typhus using a qPCR gene
expression approach based on real-time PCR. The structure and transcription of syndecan-4,
which had previously been linked to Orientia tsutsugamushi (causative agent of scrub typhus)
infection, was compared among Rattini (typhus-positive) and Murini (typhus-negative)
rodents. Although, it was not possible to conclusively link the structural variation observed
between Rattini and Murini with carrier status, a link was identified between underexpression
of syndecan-4 in Murini and seropositive Rattini rodents, compared to those that were
seronegative. This suggests that the reduced levels of syndecan-4 transcription in Murini and
Rattini is linked to the poor carrier status of Murini, and to increased longevity of
seropositive Rattini (i.e., predominant host of Orientia), highlighting aspects that need further
investigation. / AFRIKAANSE OPSOMMING: Die Rattus sensu lato kompleks, wat die belangrike biomediese model spesie Rattus
norvegicus huisves, bevat ‘n groep knaagdiere wat van kliniese, landbou, en epidiomologiese
belang is. Hierdie studie bevat ‘n omvattende sitogenetiese molekulêre vergelyking binne
hierdie kompleks. Die kariotipes van 11 Rattus s. l. spesies en Hapalomys delacouri is
ondersoek met die gebruik van konvensionele sitogenetiese tegnieke. Die data dui daarop, in
kontras met vorige bevindinge, dat die bruikbaarheid van kariotipes om Asiese knaagdiere te
identifiseer beperk is, aangesien min spesies-spesifieke chromosoom merkers geidentifiseer
kon word. Om die gebeure wat tot die morfologie en komposisie van die huidige kariotipes
gelei het, te verstaan, is nege van die 11 Rattus s. l. spesies met behulp van chromosoom
fluoressente hibridisasie ondersoek. Dit het die ontdekking van ‘n rare konvergente
geslagschromosoom-outosoom translokasie in H. delacouri en B. savilei tot gevolg gehad.
Die vaslegging hiervan is heel moontlik bevoordeel deur die teenwoordigheid van
interkalerende heterchromatien blokke (IHBs) by die grens van die translokeerde segmente.
Hierdie resultate dui daarop dat Rattus s. l. deur ‘n stadige tempo van chromosoom
verandering gekenmerk word, wat in skrille kontras staan met die hoë aantal chromosoom
herrangskikkings wat in meeste ander murid knaagdiere geidentifiseer is. Vanuit hierdie data
kon die eerste oerouer kariotipe van die Rattini bepaal word. Die gebruik van hierdie data in
kombinasie met beskikbare vergelykende kaarte het dit moontlik gemaak om die vorige
hipotetiese oerouer murid kariotipe te hersien. BAC-kartering het dit moontlik gemaak om
sonder twyfel vas te stel dat die polimorfisme wat chromosoom pare 1, 12 en 13 in die Rattus
kariotipe affekteer, die resultaat van perisentriese omsetting is. Die analise van genomiese
eienskappe, soos telomere, Ag-NORs en satelliet DNA dui op ‘n beperkte patroon van
chromosoom evolusie. Die bestudeerde rot satelliet DNA familie blyk takson (Rattus)
spesifiek te wees met ‘n onlangse oorsprong, wat ooreenstem met die terugvoer model van
satellite-evolusie.
Die vergelykende aard van hierdie studie het gelei tot die verdere analise van die spesies in
die Rattus s. l. kompleks in terme van hul moontlike rol as draers van “scrub typhus” deur
gebruik te maak van qPCR geen uitdrukking, wat gebasseer is op “real-time” PCR. Die
struktuur en transkripsie van syndecan-4, wat in die verlede aan Orientia tsutsugamushi
(veroorsakende agent van scrub typhus) infeksie gekoppel is, is tussen Rattini (typhuspositief)
en Murini (typhus-negatief) knaagdiere vergelyk. Ten spyte daarvan dat dit nie
moontlik was om die strukturele variasie tussen Rattini en Murini met draer status te koppel
nie, is daar wel ‘n skakel tussen die verlaagde uitdrukking van syndecan-4 in Murini en seropositiewe
Rattini knaagdiere, in vergelyking met die wat sero-negatief was, gevind. Dit stel
voor dat die verlaagde vlakke van syndecan-4 transkripsie in Murini en Rattini aan die swak
draer status van Murini, asook die verhoogde langslewendheid van sero-positiewe Rattini
(i.e., oorheersende gasheer van Orientia), gekoppel is. Hierdie bevindinge beklemtoon
sekere belangrike aspekte vir verdere navorsing.
|
47 |
Aspects of the biology, specific status and control of the bedbugs Cimex lectularius and Cimex hemipterus in northern Natal and KwaZulu.Newberry, Keith. 20 June 2014 (has links)
The bedbugs Cimex lectularius and C. hemipterus (Hemiptera:
Cimicidae) have been identified from a study area in
northern Natal and KwaZulu. South Africa, between 26° 45' S
and 28° 45' S, and 32° 00 ' E and 32° 52' E. Morphological
behavioural data suggest that the pigeon bug, C.
columbarius, which closely resembles C. lectularius, is not
present in Zulu huts. Two characters are suggested to
supplement Usinger's (1966) key for distinguishing the
nymphal stages of C. lectularius, and a key is presented for
the case of G. hemipterus. Distinguishing features between
the nymphal stages of the two species are also given. The
two species were found to be sympatric over most of the
study area, with C. hemipterus the more plentiful species in
the north and apparently still in the process of invading
the study area. Evidence was found that C. hemipterus
replaces C. lectularius in huts where initially both species
were found, and this agrees with laboratory findings that
interspecific mating tends to shorten the life span and
reduce the egg production of female C. lectularius females.
Interspecifically mated female C. lectularius can be
recognised by an easily visible morphological change in the
reproductive system (Walpole, 1988b) and this character was
used to prove that interspecific mating takes place in the
wild.
The size and life-stage composition of bedbug infestations
were investigated together with factors likely to affect
their growth. Cimex hemipterus was found not to be at a disadvantage as regards rate of egg production despite low
temperatures in the wild, which suggested that such
interspecific differences apparent in the laboratory may be
an artifact. The specific status of C. lectularius and C.
hemipterus are discussed, with particular reference to their
cross-mating in the wild and the production of a hybrid. The
acceptability of the Recognition Concept of species
(Paterson, 1985) is
considered
in detail. The
susceptibilities of wild bedbugs of both species to DDT,
dieldrin and fenitrothion were tested in comparison with a
susceptible strain of C. lectularius. Field trials of
bendiocarb, deltamethrin and fenitrothion were carried out
involving monitoring by bioassay and insecticidal knockdown.
Subsequent to successful bedbug control operations,
reinfestation rates and rates of replastering of mud walls
of huts (an indigenous method of attempted bedbug control
inimicable to malaria control operations) are assessed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.
|
48 |
Genetic variability of Chaerephon atsinanana (Chiroptera) within the context of the Afro-Malagasy Molossidae : a mitochondrial and nuclear perspective.Napier, Melanie Carmel. 25 November 2013 (has links)
This study has focused on genetic variability and structure in Chaerephon atsinanana, a newly-described molossid bat found in the mid to southern region of the eastern watershed of Madagascar. As these bats are strong fliers, and are able to traverse the riverine and mountain barriers within the landscape, it was hypothesized that they would show relatively low levels of intraspecific genetic structure, consistent with patterns shown for other Molossidae on Madagascar (Mormopterus jugularis, Mops midas, Mops leucostigma, and C. lecuogaster.
Phylogenetic (neighbor-joining, parsimony and Bayesian inference) and population genetic analyses of maternally-inherited mitochondrial control region sequences revealed the presence of 6 distinct haplotype groups separated by genetic distances of up to 8.14% (mean 4.95%). There were high levels of genetic structure among the haplotype groups (overall FST= 0.994). Thus the hypothesis of low levels of genetic structure was rejected. Bayesian skyline analyses and significantly ragged mismatch distributions were consistent with ancient stable C. atsinanana populations which were of constant size during the last two major Pleistocene glacial periods. This made retreat into and expansion from glacial refugia an unlikely explanation for such high levels of structure. An alternative hypothesis is that C. atsinanana haplotype groups are spatially structured as a result of philopatry. As mitochondria are maternally-inherited, this data is consistent with the existence of female philopatry in C. atsinanana.
The second aim of this study was to examine the genetic structure of C. atsinanana with nuclear sequence markers, which are biparentally-inherited, in order to provide information on the male contribution to gene flow and the possible presence of male philopatry in this molossid bat species. The initial objective was to amplify and sequence candidate nuclear markers in order to identify those which were variable among C. atsinanana samples. I attempted to amplify and sequence a set of 12 nuclear markers, identified from the literature, which had been reported to show high levels of variability, or which were untested and showed the potential for high levels of variability. Of these, the intron markers PNPO-3, SLC38A7-8, CARHSP1-1, GAD2-1, OSTA-5 had not previously been used in phylogenetic analyses while FES, GHR, RHO1 CHRNA1, STAT5, PRKC1 and THY had been. I was not able to amplify and/or sequence SLC38A7-8, CARHSP1-1, GAD2-1, OSTA-5, CHRNA1, STAT5 and THY across the range of the C. atsinanana samples. PNPO-3, FES, GHR, RHO1 and PRKC1were successfully amplified and sequenced, but showed no variability and very little polymorphism, and were therefore unsuitable for testing hypotheses related to genetic variability of C. atsinanana populations. These five nuclear sequence markers were further used to investigate phylogenetic relationships among 5 genera (Chaerephon, Mops, Mormopterus, Otomops and Sauromys) and 13 species of Afro-Malagasy molossid bats, and to provide a nuclear phylogenetic perspective on the newly-described C. atsinanana. PNPO-3 is a novel nuclear intron marker, previously unused in phylogenetic studies. This intron provides resolution primarily at the genus level, and is less informative at interspecific level. These five nuclear markers were combined with already existing mitochondrial cytochrome b (Cyt b) and nuclear Rag2 data retrieved from GenBank.
This study provides strong support for the monophyly of the Chaerephon and Mops taxa included, with the exception of C. jobimena, which was weakly associated with this group. There was no support for the generic affiliation of C. jobimena or for the monophyly of either of the genera Chaerephon or Mops individually. This leads to the suggestion that Mops and Chaerephon be combined into a single genus, with crown age of 14.82 (6.44-25.54) MYA, or 21.97 (12.16-33.44) MYA if C. jobimena is included. Otomops forms a strongly supported clade consistent with its generic status, comprising two subclades corresponding to the recognised sister species O. martiensseni and O. madagascariensis, which last shared a common ancestor 8.35 (2.87-17.47) MYA. This study provides good nuclear support for the mitochondrially-defined subclades of O. martiensseni, which last shared a common ancestor 4.18 (1.08-9.96) MYA. It would appear appropriate to name the clade from north east Africa and Arabia as a new species of Otomops, as the clade from southern and western Africa includes the type locality. This study provides weak support based on individual gene regions for associations of Sauromys with Otomops and Mormopterus, although these do not stand up in the concatenated datasets which offer better resolving power, indicating that Sauromys is not phylogenetically associated with Chaerephon/Mops, Otomops and Mormopterus. These results provide some support for the membership of Mormopterus in the proposed Old World Molossid tribe, Tadarini, but also support Mormopterus as a basal genus within the Molossidae, consistent with its designation as a separate tribe, Mormopterini. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2013.
|
49 |
Bushbuck ecology and management at Shongweni Dam and Game Reserve.Coates, Gregory David. 29 November 2013 (has links)
Msinsi Holdings (Pty) Ltd are considering the introduction of nyala to Shongweni Dam and Game Reserve in KZN. This reserve has a naturally resident population of bushbuck and is located beyond the natural distribution of nyala. Concerns for competition between these two species causing declines in bushbuck numbers elsewhere prompted the present study. The main aim of the present study was to determine some aspects of the ecology of bushbuck within the reserve to assist with decision-making regarding the introduction of nyala and species specific-management of bushbuck at the study site.
Bushbuck home range and habitat utilisation was investigated with the aid of radio telemetry and Geographical Information Systems. Estimates of total home range
size for males using minimum convex polygons (MCPs) and fixed kernels (FKs) were
33.9 ha and 32.1 ha respectively. Estimates of total home range size for females using
MCPs and FKs were 12.0 ha and 13.5 ha respectively. A significant difference
between total home range size for gender (male and female) was found but there was
no significant difference for age (adult and subadult). Bushbuck typically utilised one
core area within their home ranges in which 50 % of their time was spent in
approximately 17 % and 11.7 % of their total home range for males and females
respectively. A substantial overlap in total home range and core areas between animals was found.
Bushbuck showed preference for short thickets and avoidance of low closed
grasslands. High reedbeds were utilised in proportion to their availability and tallwoodlands were not utilised by the study animals, but were observed to be utilised by other non radio-collared bushbuck. Habitat preference was a consequence of
favourable cover being provided by the structure of the vegetation and the occurrence
of favourable foraging species. Bushbuck utilisation of topographical aspect was
largely determined by the vegetation type that occurred on the respective slopes.
Estimations of bushbuck density and abundance were made using sighting
efforts, drive counts, and mark-resightings. Sighting efforts using distance sampling
during spring were found to be the most effective in terms of accuracy and man-hour
costs, however, these were still not considered to be precise estimations of the total
bushbuck population at SDGR, but would be useful for monitoring population trends
as a result of the high repeatability and simplicity of the method. Sex, age ratios and nocturnal activity were determined using field
classification. The field classification method of age and sex ratio determination used
during the present study was found to be very subjective and was therefore suggested
to have produced ratios which may be largely biased towards the female component
of the population. This in turn also effected the determination of social organization
and was evident when compared to previous studies. Bushbuck activity determined
from radio telemetry and sighting efforts produced results that corresponded with all
previous studies, showing bushbuck to be largely nocturnal, moving much larger
distances at night than during the day, and spending most of their time walking and feeding at night.
The status and management of synoptic bushbuck and nyala in KwaZulu-Natal
was also investigated by means of a questionnaire survey. From the opinions of
landowners and reserve managers, the status of bushbuck sharing a sympatric
relationship with nyala in KwaZulu-Natal (KZN) appeared to be stable to declining,
whereas nyala status was increasing. This trend was suggested to be a result of
competition for resources between the two species. Northern KZN recorded a higher
frequency of this trend (57.7%, n = 26) compared to the Midlands (35.7%, n = 14), as
did Ezemvelo KZN Wildlife Reserves (85.7%, n = 7) compared to privately owned
properties (42.4%, n = 33). Very little species-specific management for nyala and
bushbuck occurred in reserves that participated in the present survey. / Thesis (M.Sc.)-University of KwaZulu- Natal, Pietermaritzburg, 2003.
|
50 |
The status and ecology of the leopard tortoise (Geochelone pardalis) on farmland in the Nama-Karoo.McMaster, Megan Kay. 13 December 2013 (has links)
The Family Testudinidae (Suborder Cryptodira) is represented by 40 species worldwide
and reaches its greatest diversity in southern Africa, where 14 species occur (33%), ten of
which are endemic to the subcontinent. Despite the strong representation of terrestrial
tortoise species in southern Africa, and the importance of the Karoo as a centre of
endemism of these tortoise species, there is a paucity of ecological information for most
tortoise species in South Africa. With chelonians being protected in < 15% of all southern
African reserves it is necessary to find out more about the ecological requirements, status,
population dynamics and threats faced by South African tortoise species to enable the
formulation of effective conservation measures.
The Leopard Tortoise (Geochelone pardalis) is the largest of the southern African
species and has a wide distribution range, occurring in a variety of habitats. There is a paucity
of ecological information about Leopard Tortoises in most of these habitats, especially arid
and semi-arid regions. The broad aim of the study was to comprehensively investigate the
ecology of Leopard Tortoises on farmland in the semi-arid Nama-Karoo biome, and use the
ecological information to make recommendations for conservation. An investigation
was made to determine the population size, sex and age distributions, density, biomass, and
morphometrics of Leopard Tortoises in the Nama-Karoo. It was predicted that Leopard
Tortoises would either be similar in size to Leopard Tortoises in other habitats or larger in
order to buffer the effects of extreme temperatures by decreasing the surface-to-volume ratio.
In addition, it was predicted that Leopard Tortoises would have a smaller population size,
and occur at a lower density and biomass per hectare than those tortoises in mesic habitats. A total of 92 tortoises were caught, and 3899 observations made on Leopard
Tortoises on 5500 hectares of farmland. Fourteen tortoises were radio tracked which
allowed for repeated observations throughout the year. The population was skewed
towards adults, and indicates a low hatchling recruitment. Female Leopard Tortoises were
significantly larger than males with respect to all morphometric measurements. A male to
female sex ratio of 1: 1.6 was obtained, which was not significantly different from 1: 1. A population estimate of 57.64 ± 3.99 tortoises for the 5500 ha area was obtained using a
mark-recapture sampling method. Density of tortoises was extremely low at 0.017 tortoises.ha ¯¹, with a biomass of 0.002 kg.ha ¯¹. Population size, density, biomass and morphometrics were compared with Leopard Tortoise populations in other areas. Leopard
Tortoises were larger in size in the semi-arid Nama-Karoo compared with Leopard
Tortoises in other areas, probably a mechanism to reduce the effects of extreme
temperature fluctuations, and were found at a much lower density. Knowledge of the
home range size, home range overlap and seasonal change in home range is imperative to
the understanding and conservation of the Leopard tortoise. Home range size, percentage
overlap and mean daily distances moved were investigated for Leopard Tortoises as a
function of season, gender and body mass. Home range and movement data were
calculated for 36 Leopard Tortoises (22 females, 14 males), 14 of which were telemetered (8 females, 6 males), and 22 of which were recaptured 10 or more times (14 females and
8 males) over a period of two years. Mean (±SE) home range size for adult Leopard
Tortoises was 205.41 ± 45.57 ha. Home range size was not significantly different between
males and females, however females had larger home ranges than males. Mean home range size of males was 133.27 ± 32.90 ha, and of females was 251.32± 70.56 ha. There
was a significant difference in home range size between telemetered tortoises (413.81 ±
89.46 ha), and those recaptured 10 or more times (72.79 ± 18.89 ha). It is suggested that
unacceptable variation in home range size estimations occur when radio telemetry is not
used to recapture tortoises throughout the year. No significant relationship between home
range size and body mass was found for all tortoises or between sexes. Significant
seasonal and gender variation existed in the seasonal home range sizes. Females had
larger home ranges than males in all seasons except spring. Mean daily distance moved
by Leopard Tortoises was 136.13 ± 8.94 m with males moving further overall daily than
females (males: 161.10 ± 11.8 m; females: 117.07 ± 12.87), but not significantly so.
Mean daily distance moved per season was significantly different between the sexes.
Females covered the largest mean daily distance in autumn and males in spring.
Considerable variation existed in the amount of home range overlap both within and
between sexes. Overlap percentages ranged from 5% to 90%, with home ranges most
frequently overlapping by 20%. Home range size and daily distances moved in the Nama-Karoo
are larger than for Leopard Tortoises in other habitats. This has strong implications
for the size of reserves needed in conservation efforts with regard to this and perhaps
other, species in arid or semi-arid areas.
Seasonal activity patterns of Leopard Tortoises were investigated as a function of
rainfall, sex, time of day, temperature and time after sunrise. It was predicted that due to
seasonal rainfall, and the subsequent increase in food available, the activity patterns of
Leopard Tortoises would vary greatly between seasons, but that the primary constraint on activity levels within a season, would be ambient temperature. Type of activity, time of
day that the activity was performed, and amount of time spent performing each activity,
differed significantly between the seasons. There was no overall seasonal significant
difference between the sexes and the level of activity, however, in certain seasons and
with regard to specific activities, there were significant differences between the sexes.
Activity patterns were primarily bimodal in summer and autumn, and unimodal in winter
and spring, with non-thermoregulatory activities, for example walking and feeding, being
performed primarily in the afternoon. There was a significant positive correlation between
the number of tortoises caught and rainfall per season, but activity levels and the
percentage of tortoises walking and feeding was not correlated with seasonal rainfall. The
time of day that an activity was first performed in each season, was primarily a function
of the time after sunrise and only secondarily of temperature. The response of Leopard
Tortoise activity to rainfall, time of day, temperature and time after sunrise, is discussed.
With Leopard Tortoises being ectotherms, they rely largely on behavioural
thermoregulation to moderate the effects of daily and seasonal fluctuations in ambient
temperature on body temperature. Extensive use is made of refuges to facilitate this
behavioural thermoregulation. The Nama-Karoo experiences wide temperature
fluctuations both daily and seasonally, and therefore the types and seasonal use of refuges
by the Leopard Tortoise, in addition to the orientation of the exits and of the tortoises
within the refuges, was investigated. A wide variety of refuges were used, but Lycium spp., Eberlanziaferox (Doringvygie), Opuntiajicus (American Prickly Pear) and grass
clumps were preferred as refuges. There was seasonal variation in the use of these refuges that further depended on whether the refuges were used as forms or shelters. Leopard
Tortoises in spring and winter often remained in the same refuge for the entire season, or returned to the same refuge on consecutive nights.
There was seasonal and behavioural variation in a) compass direction that the
tortoises were facing within a refuge, b) compass direction that exits of the refuges were
open to, and c) portion of the shell of each Leopard Tortoise within a refuge that was
exposed to sun radiation. Tortoises in winter and spring used these three factors to
maximise the amount of solar radiation received on their carapace, while tortoises in
summer and autumn used them to minimise solar radiation received. Therefore, using a combination of refuge type, exit orientation and tortoise orientation, Leopard Tortoises
were able to passively thermoregulate and further control temperature fluctuations
experienced in an extreme environment.
Leopard Tortoises on farmland in the Nama-Karoo had lower densities, larger
body sizes and much larger home ranges than Leopard Tortoises in other habitat types.
This is an important aspect to take into account when planning for the conservation of
Leopard Tortoises in semi-arid areas, and may hold further implications for other arid or semi-arid tortoise species.
Activity patterns and patterns of thermoregulation allow for further understanding
of the interactions between tortoises and their environment, habitat, and climate in the
wild. In addition, it further aids in the understanding of the methods used by ectotherms to thermoregulate and manipulate body temperatures, especially when living in regions of unpredictable rainfall and extreme temperatures. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
|
Page generated in 0.0304 seconds