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The Role of Larval Thermal Tolerance in the Distribution of Blue Mussel Species within the Gulf of MaineLimbeck, Susan J. January 2003 (has links) (PDF)
No description available.
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Analysis of the lower distributional limit of callianassid shrimp in South Slough National Estuarine Research ReserveMiner, Jonathan Neal, 1969- January 1993 (has links)
Typescript.
Includes vita and abstract.
Bibliography: Includes bibliographical references (leaves 77-80).
Description: xii, 80 leaves : ill. ; 29 cm. / The lower distributional limits (fronts) of
callianassid shrimp populations were observed at five sites
in South Slough, Coos Bay estuary, Oregon. Fronts at four
sites exhibited similar shoreward-seaward movements while
the remaining site showed drastic population reductions.
Shrimp density and body size were found to be significantly
greater above than below the front. There was no consistent
pattern found in grain size or interstitial water content
across the front.
In a controlled predator-exclusion experiment,
resulting shrimp densities were not significantly different
among treatments. Front shifts showed no pattern in response
to treatments. These results imply that fish predation is
not responsible for front placement. Trawls taken on both
sides of the front produced similar densities of a predatory
fish, Leptocottus armatus. Because predation pressure was calculated to be roughly equal above and below the front,
Leptocottus is not expected to be responsible for position
and movements of these fronts.
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Genetic Substructure of Pacific Harbor Seal (Phoca vitulina richardsi) Populations Along the Coasts of Oregon and WashingtonDishman, Diana Lynn 01 January 2011 (has links)
It has been assumed that the considerable dispersal ability of many marine species would prevent genetic divergence in the absence of geographic isolation. However, recent work has shown that many marine species often develop differentiation among areas within their known dispersal range. This 'paradox' of marine divergence is particularly important among marine mammal species where behavior can restrict gene flow. To investigate genetic substructure within such a species, I used tissue samples collected from 63 stranded Pacific harbor seals (Phoca vitulina richardsi) in Washington and Oregon between 2006 and 2010 for population stock analysis. DNA was extracted from frozen tissues, and a 551 bp fragment of mtDNA control region sequence and eight microsatellite loci were amplified to investigate localized genetic structure. Minimum spanning network and haplotype frequency analyses of mtDNA sequences indicated that while haplotype lineages are not isolated within a sampling region, there is some evidence of regional differentiation. On the other hand, microsatellite data suggest a lack of substructure among the animals sampled, with only a weak signal of limited gene flow between Puget Sound and coastal areas. Biased dispersal among age classes was also suggested, with juveniles showing less differentiation among areas than adults. Regardless of the historical scenario which has led to this complex pattern of genetic structure in Pacific harbor seals across the Pacific Northwest, my results suggest higher levels of exchange among areas than previously suspected, and will have important consequences for future management considerations for these stocks.
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Biodiversity of saproxylic Coleoptera in 'old-growth' and managed forests in southeastern OntarioZeran, Rebecca January 2004 (has links)
No description available.
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Phylogeographic variation of the Karoo bush rat, Otomys unisulcatus : a molecular and morphological perspectiveEdwards, Shelley 03 1900 (has links)
Thesis (MSc (Botany and Zoology))--Unkiversity of Stellenbosch, 2009. / Phylogeographic genetic structure has been documented for a number of southern African terrestrial taxa.
Information regarding geographic population genetic structuring in multiple taxa, with differing life
histories, can provide insights into abiotic processes such as vicariance. A fragment of the cytochrome b
mitochondrial DNA gene of a plains-dwelling species, Otomys unisulcatus, was sequenced and analysed.
Two closely related geographic assemblages were found. The first assemblage (lowland group) contains
populations from both the eastern and western parts of the species range, and the second comprises
populations from the Little Karoo (central group). The lowland group was shown to be in a state of
population expansion after a relatively recent mitochondrial DNA (mtDNA) coalescence, while the genetic
signature of the central assemblage was characterized by more genetic diversity indicative of an older
lineage/genetic refuge. Areas of higher elevation (namely mountain ranges) appeared to be the main factor
limiting gene flow between these two groups. Aridification cycles due to glacial maximum periods
probably resulted in increased dispersal leading to the widespread distribution of common haplotypes
throughout the lowland group.
Morphological variation in skull shape and size has been shown to follow environmental clines in some
rodents. Geometric morphometric analyses on the ventral and dorsal views of the craniums of O.
unisulcatus were utilised to test whether the population groupings obtained in the genetic analyses would be
recovered by morphometric analyses. In addition, it was also investigated which of the environmental
factors investigated influenced skull shape and size. The genetic groupings were not recovered for either the
cranial shape or size. Size variation in the females correlated positively with annual rainfall, and so by
proxy with habitat productivity, indicating that females which inhabited areas with lower rainfall would be
larger. The significant relationship between females’ centroid sizes and rainfall was thought to be as a result
of the increased nutrient requirement by this gender in the production of offspring. The males did not show
a significant correlation between any of the environmental variables and centroid size. There was a
significant difference between the skull shapes of the genders, further verifying the sexual dimorphism in
the species. Three major clusters were found (according to cranium shape) using a Two-Block Partial Least
Squares Analysis (2B-PLS), which relate to the biome boundaries within the species’ range. Variations in shape were attributed to the varying needs for strong masticatory muscles resulting from differing diets.
The skull shapes of specimens occurring along the escarpment were intermediate between the first two
clusters. Cranial shape in the male dorsal view dataset was significantly correlated with the environmental
variables block, possibly due to the much lower minimum temperature in the Sutherland population (a
population which was not included in the female analyses). It was concluded that differing diets of
individuals in the respective biomes influenced the shape of the cranium of both genders. The sexual
dimorphism in the cranium shapes may be as a result of the females digging tunnels (using their teeth)
underneath the stick nests. Otomys unisulcatus show high levels of phenotypic plasticity throughout the
range and it thus appears that the species can adapt fast to the different environmental variables.
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The relevance of the Greater Cederberg Biodiversity Corridor (GCBC) for reptile conservationMeyer, Anita 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The Greater Cederberg Biodiversity Corridor (GCBC) is a large-scale conservation
corridor situated in the south-western region of South Africa. Delineation of the GCBC
was largely based on by vegetation data. The relevance of the GCBC for the
conservation of the reptilian fauna in the area south of 31°S and west of 21°E is assessed
in the present study. This entailed determining the GCBC’s coverage of regional reptile
diversity patterns and assessing its potential conservation significance during possible
climate induced changes in reptile distributions.
Reptile species point distribution data from the preliminary (2007) SARCA (South African
Reptile Conservation Assessment) database was used. Under-representation of the
Tankwa Karoo in the dataset required a field survey of this region. Additionally, the
biogeographical influence of the arid Tankwa Karoo Basin on the distribution of reptiles in
the south-western districts of South Africa was investigated. Turnover across the Basin is
high, species richness is lower than in surrounding mountainous areas and there are no
species endemic to the area. The Tankwa Karoo Basin acts as a dispersal barrier for
many reptile species occurring in the surrounding more mesic areas. At the same time,
the ranges of a number of typical northern, arid adapted species extend southward along
the Tankwa Plains. A number of species range extensions in the region are reported.
Patterns of endemism, species richness and turnover were plotted from the point
distribution data at quarter and eighth degree square resolution. Extensive sampling bias
towards reserves and populated areas is apparent from the reptile species richness plots.
This pattern is more pronounced for snakes than lizards. Reptile richness is particularly
high along the north-south section of the Cape Fold Mountains and also relatively high
along the south-western coast, peaking in the Lambert’s Bay area. The majority of the 20
reptile species endemic to the study area are associated with one of two identified centres of endemism: the Greater Cederberg area, or the narrow coastal zone stretching from the
Lambert’s Bay area to the Cape Peninsula. An additional third set of endemics comprised
of melanistic forms restricted to a number of different refugia, notably, Landroskop, the
Cape Peninsula, Sladanha-Langebaan region, Piketberg Mountains and a confined area
along the western section of the Cape Fold Mountains. Species richness and endemism
patterns co-vary within the study area.
Biotic regions were identified through hierarchical clustering of grid cells according to
shared species occurrences. A Northern, Southern, Central and Western biotic region
was identified. Classification tree methodology (CART) and Canonical Correspondence
Analysis (CCA) were used to characterise defined biotic regions in terms of selected
environmental variables. Four sets of species assemblages are described on the basis of
these biotic regions – two major and two minor ones. Of the major assemblages the
Northern assemblage can be described as an arid zone one and the Southern
assemblage as a mesic zone one. The minor Central assemblage, comprising mainly
rock-dwelling forms, represent evolutionary leftovers as a result of climate change induces
cycles of contraction and expansion of arid and mesic faunas. The other minor one, the
West Coast assemblage could be considered a sub-assemblage of the Northern one, with
particular adaptation to the coastal climate. Environmental characterisation of the biotic
regions reveals that these groupings are supported by an environmental signal. The
contiguity of four distinct sets of reptiles, each with its own set of environmental
requirements, in this relatively small geographic area clearly indicates that the southwestern
region of South Africa is biogeographically complex.
The GCBC incorporates the largely coinciding centres of endemism and richness along
the West Coast and the greater Cederberg area. Although the centre of endemism for
melanistic reptile forms, in the Saldanha-Langebaan area, falls just south of the GCBC
boundary, the Corridor fulfils the requirements for effective conservation of reptiles in the area to a large degree. The north-south dispersal pathways provided by the Corridor
along the Cape Fold Mountains is believed to be adequate to buffer climate change
effects, however there is concern about its ability to contribute to the persistence of the
assemblage associated with the narrow coastal zone in the west. / AFRIKAANSE OPSOMMING: Die Groter Cederberg Biodiversiteit Korridor (GCBK) is ‘n grootskaalse bewaringskorridor
wat in die suid-westelike deel van Suid-Afrika geleë is. Die grense van GCBK is
gebasseer op plantegroei data. In die huidige studie word die betekenis van die GCBK vir
die bewaring van die reptiel fauna in die gebied suid van 31°S en wes van 21°O
assesseer. Die mate waartoe die GCBK die patrone van reptieldiversiteit in die streek
inkorporeer, asook die korridor se potensiaal om voorsiening te maak vir reptiel
verspreidingsgebiede wat moontlik as gevolg van potensiële omgewingsverandering kan
verskuif.
Die beskikbare puntverspreidingsdata van die voorlopige (2007) SARCA (South African
Reptile Conservation Assessment) databasis is gebruik. Swak verteenwoordiging van die
Tankwa Karoo in die datastel het ‘n veldopname van die gebied genoodsaak. Verder is
die biogeografiese invloed van die ariede Tankwa Karoo Kom op die verspreidingspatrone
van reptiele in die suid-westelike deel van Suid-Afrika ook ondersoek. Die spesie omset
van beide Noord na Suid en Wes na Oos oor die Tankwa is hoog, die spesierykheid is
aansienlik laer as in die omringende bergagtige gebiede en daar is geen spesies wat
endemies is tot die Tankwa Karoo nie. Die Tankwa Karoo Kom dien as ‘n barieêre teen
spreiding vir sommige reptielspesies wat in die omringende gematigde gebiede voorkom.
Terselfdertyd reik die verspreidings van ‘n aantal tipiese droogte aangepasde spesies
vanuit die noorde suidwaarts langs die Tankwa Vlaktes. Nuwe verspredingsrekords wat
‘n paar spesies se gebiede uitbrei word ook raporteer.
Die puntverspreidingsdata is geruik om die patrone van endemisme, spesierykheid en
omset op kwart- en agtstegraad resolusie te plot. Spesierykheid kaarte toon ‘n duidelike
neiging tot deegliker opnames in reservate en bewoonde gebiede. Hierdie patroon is meer opmerklik vir slange as akkedisse. Reptielrykheid is besonders hoog langs die
noord-suid as van die Kaapse Plooiberge en ook relatief hoog langs die suid-wes kus met
‘n maksimum in die Lambertsbaai omgewing. Die meerderheid van die 20 reptielspesies
wat endemies is aan die studie area is met een van twee geïdentifiseerde sentrums van
endemisme geassosieer: die Groter Cederberg area óf die nou kussone wat vanaf
Lambertsbaai tot Kaappunt strek. ‘n Derde stel endemiese spesies wat uit melanistiese
vorme bestaan, is beperk tot ‘n aantal refugia, naamlik, Landroskop, Kaappunt, Saldanha-
Langebaan omgewing, Piketberg berge en ‘n beperkte area langs die westelike dele van
die Kaapse Plooiberge. Spesierykheid en endemisme patrone stem grootliks ooreen
binne die studie area.
Roosterselle is op grond van gedeelde spesiesamestellings met behulp van ‘n hieragiese
groeperingsmetode (Incremental Sum of Squares) gegroepeer. Vier bio-areas, nl. ‘n
Noordelike-, Suidelike-, Sentrale en Westelike bio-area is identifiseer. Klassifikasieboom
metodologie (Classification and Regression Trees, CART) asook Kanoniese Annalises
(Cannonical Correspondence Annalysis, CCA) is gebruik om hierdie geografiese areas in
terme van ‘n aantal omgewingsveranderlikes te karakteriseer. Vier spesieversamelings,
twee groter en twee kleiner versamelings, is in ooreenstemming met hierdie vier areas
geïdentifiseer. Die Noordelike en Suidelike spesieversamelings is die groteres en kan
beskryf word as die faunas van onderskeidelik ‘n ariede en gematigde sone. Die kleiner
Sentrale versameling bestaan hoofsaaklik uit rots-lewende spesies en mag die
evolusionêre oorblyfsels verteenwoordig van ariede en gematigde faunas waarvan die
verspreidings herhaaldelik as gevolg van klimaatsveranderingsiklusse uitgebrei en
gekrimp het. Die Weskus versameling is ook ‘n kleiner een en kan as ‘n sub-versameling
van die Noordelike een beskou word, maar spesifiek tot die kus klimaat aangepas. Die
klassifikasie van hierdie bio-areas word ondersteun deur die analiese van die
omgewingsveranderlikes. Die feit dat vier kenmerkende versamelings reptiele, elk met sy besondere omgewingsvereistes, in hierdie relatief klein geografiese area ontmoet, dui
daarop dat die suid-westelike deel van Suid-Afrika biogeografies kompleks is.
Die GCBK inkorporeer die grootliks ooreenstemmende sentrums van endemisme en
rykheid wat langs die Weskus en in die groter Cederberg area voorkom. Alhoewel die
sentrum van melanistiese endemiese spesies, in die Saldanha-Langebaan omgewing, net
buite die grense van die Korridor val, voldoen die GCBK grootliks aan die vereistes vir die
effektiewe bewaring van reptiele in die gebied. Die voorsiening van noord-suid
verspreidingsweë langs die Kaapse Plooiberge binne die Korridor word beskou as
voldoende om die gevolge van klimaatsverandering te buffer. Daarinteen is daar kommer
oor die vermoeë van die GCKB om ‘n doeltreffende bydrae te maak tot die voortbestaan
van die spesieversameling wat met die nou kussone langs die Weskus geassosieer is.
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Phylogeography of the Cape girdled lizard, Cordylus cordylus : investigating biogeographic patterning in the Cape floristic region (CFR)Diedericks, Genevieve 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In the present study I examined the phylogeography of the rupicolous Cape
girdled lizard, Cordylus cordylus. Samples were collected across the species
distribution range from 63 localities in the Eastern and Western Cape and Free State
provinces of South Africa, yielding a total sample size of 207 specimens. Four DNA
loci, two nuclear (PRLR, PTPN12) and two mitochondrial (16S rRNA, ND2), were
sequenced. Bayesian inference, maximum likelihood and maximum parsimony
methods were employed to test evolutionary relationships among populations,
followed by population structure analyses, divergence time estimations and niche
modelling. My results confirm the species monophyly and revealed the presence of
two distinct clades. Clade 1 comprised specimens from the western and southern
portions of the Western Cape coast, while clade 2 comprised specimens from the
southern and eastern Cape coast and adjacent interior of the Eastern and Western
Cape and Free State provinces. An area of sympatry between the two clades was
observed in the Breede river valley. The divergence time estimates revealed an
Early Pliocene (4.31 Ma), Late Miocene (6.01 Ma) divergence for each of the two
clades retrieved. Phylogeographic data suggest that clade 1 is younger (lower
haplotypic and nucleotide diversity), in comparison to clade 2. Furthermore, the
niche modelling shows that C. cordylus occupies a wide range of unfavourable
habitats. The absence of marked phylogeographic patterning within clades is very
uncharacteristic for a rupicolous vertebrate species. The ecological pliability and
generalist nature of C. cordylus presumably contributed to the observed
phylogeographic pattern and have facilitated the absence of within clade differentiation. Moreover, I suggest that microclimatic variables, rather than
geographic barriers influence the genetic structuring of C. cordylus.
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The biogeography, systematics and conservation of Phreatoicidean isopods in South AfricaGouws, Gavin 12 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Historically, isopods of the suborder Phreatoicidea were thought to be represented in southern
Africa by four species belonging to the endemic genus Mesamphisopus. This taxonomy was
based on poor collections and the extent of variation among and within populations were
poorly understood. In the present study, intensive sampling was undertaken to determine the
diversity, distribution and biogeography of phreatoicidean isopods within South Africa.
Analyses of allozyme data and mitochondrial DNA sequences (from the 12S rRNA and
protein-coding COI genes) were used to examine differentiation among populations, extricate
species boundaries (in combination with morphometric and morphological data) and to
elucidate the evolutionary relationships among taxa. Additionally, conservation units were
identified among the sampled populations and conservation threats highlighted.
First, genetic and morphometric differentiation was examined among populations identified
morphologically as M. capensis. Collection localities spanned two mountainous regions in
the Western Cape and these were separated by a coastal plain remnant. Five
morphometrically and genetically distinct species were identified. These taxa are also
geographically partitioned in two regions, which were regarded as Evolutionarily Significant
Units. Differentiation among populations of the two regions, and similar patterns in other
taxa, was attributed to Cenozoic sea-level fluctuations.
Second, populations, variably assigned to M. abbreviatus or M. depressus, were examined to
determine whether they were conspecific. A large geographic area was sampled to account
for intraspecific differentiation. Limited morphometric discrepancies were observed, with
individual populations being either similar to the M. abbreviatus or the M. depressus
syntypes. Genetic support for the recognition of a cryptic species complex among the
sampled populations was equivocal. Substantial genetic differentiation and a lack of gene
flow were observed among all populations. Clear patterns of isolation by distance were not
detected, and genetic structure appeared to be unrelated to geography or drainage systems.
The mosaic pattern of relatedness among populations was best explained by stochastic
demographic processes, such as extinction-recolonization events or population bottlenecks.Thirdly, detailed taxonomic descriptions and illustrations of six new species, identified
genetically and morphometrically among the populations included in the above analyses, were
provided. These species were largely distinguished from each other, and the four original
species, using a combination of setation, mouthpart, pleopod and uropod features.
Lastly, phylogenetic relationships among all ten recognized Mesamphisopus species, and an
additional unresolved group of populations, were examined. MtDNA data partitions and a
recoded allele frequency matrix were analysed independently and in combination. Topologies
indicated unrecognized species-diversity within an unresolved group of populations.
Evolutionary relationships, the identification of six biogeographic centres, and the dating of
divergences using a relaxed Bayesian clock suggested that differentiation and speciation
within Mesamphisopus was largely allopatric or vicariant and driven by Mesozoic sea-level
and climate change. Chance long distance dispersal events would, in turn, explain spurious
phylogenetic relationships and distributions.
This study contributes significantly to the understanding of the diversity and the conservation
of the little-studied southern African freshwater invertebrates. Moreover, this study is the first
to investigate genetic and morphometric differentiation, and phylogenetic relationships, below
the generic level within the Phreatoicidea; thus establishing a methodological and theoretical
framework for species delineation and the accurate determination of biodiversity within
individual phreatoicidean genera. / AFRIKAANSE OPSOMMING: Isopoda van die suborder Phreatoicidea was histories in suidelike Afrika verteenwoordig deur
vier spesies wat almal aan die endemiese genus Mesamphisopus behoort. Hierdie taksonomie
is op ’n beperkte hoeveelheid versamelings gebaseer en die omvang van variasie tussen (en
binne) bevolkings was swak verstaan. In die huidige studie is ekstensiewe versameling
onderneem om die verspreiding, diversiteit asook biogeografie van dié Isopoda in Suid Afrika
te bepaal. Analises van allosiem data en mitokondriale DNS volgorderbepalings (van die 12S
rRNS en die proteïenkoderende COI geen) was gebruik om differensiasie tussen bevolkings te
ondersoek, om (in kombinasie met morfometriese en morfologiese data) spesiesgrense te
bepaal asook om die evolusionêre-verwantskappe tussen taksa te definieer. Benewens word
bewaringseenhede binne die studie-bevolkings geïndentifiseer en moontlike bedreigings
uitgelig.
Eerstens is genetiese en morfometriese differensiasie tussen bevolkings, wat as M. capensis
geïdentifiseer is, ondersoek. Versamelingslokaliteite was versprei oor twee bergagtige streke
in die Weskaap wat geskei word deur ’n voormalige kusvlakte. Vyf morfometries- en
geneties-afsonderlike spesies is geïdentifiseer. Dié taksa was geografies geskei tot die twee
streke, wat elk as ’n Evolusionêre Beduidende Eenheid (ESU) gesien kan word.
Differensiasie tussen populasies van die twee streke en vergelykbare patrone binne ander
taksa word aan Cenosoïese seevlak veranderings toegeskryf.
Tweedens is bevolkings wat as M. abbreviatus óf as M. depressus geïdentifiseer kan word
ondersoek om te bepaal of hulle konspesifiek is. Bevolkings is oor ’n groot geografiese
gebied versamel om intraspesifieke variasie in aanmerking te neem. Beperkte morfometriese
verskille is waargeneem – enkel bevolkings was morfometries identies aan of die M.
abbreviatus of die M. depressus sintipes. Genetiese getuienis vir die herkenning van ’n
kriptiese spesieskompleks was dubbelsinnig. Bevolkings is gekenmerk deur merkbare
genetiese differensiasie en die afwesigheid van geenvloei. Duidelike bewys van isolasie-metafstand
was nie waargeneem nie en genetiese struktuur was nie verwant aan geografiese
ligging of riviersisteme nie. Die mosaïese patroon van verwantskappe is moontlik teweeg
gebring deur stogastiese demografiese prosesse soos uitsterwing en hervestiging of deur
afnames in bevolkingsgrootte.Derdens is omvattende taksnomiese beskrywings en illustrasies van ses nuwe spesies wat deur
bogenoemde analises geneties en morfometries uitgelig was, verskaf. Dié spesies is van
mekaar, asook die ander vier spesies onderskeibaar deur ’n kombinasie van setasie-,
monddeel-, pleiopoot- en uropooteienskappe.
Laastens is die filogenetiese verwantskappe tussen al tien herkende Mesamphisopus-spesies
en ’n groep bevolkings waarvan verhoudings onseker was, ondersoek. MtDNS datastelle en
’n hergekodeerde alleelfrekwensie matriks is afsonderlike en in kombinasie geanaliseer.
Topologië het onherkende spesies-vlak diversiteit binne die bogenoemde groep bevolkings
aangedui. Evolusionêre verwantskappe, die herkenning van ses biogeografiese gebiede, en
die bepaling van tye van divergensie (d.m.v. ’n ontspanne Bayesiaanse molekulêre klok) het
aangetoon dat spesiasie binne Mesamphisopus grootliks allopatries was en deur Mesosoïese
seevlak- en klimaatsveranderings teweeg gebring is. Toevallige lang-aftstand verspreiding
kon dan eienaardige filogenetiese verhoudings en verspreidings verklaar.
Dié studie lewer ’n wesenlike bydrae tot die kennis van die diversiteit en tot die bewaring van
die onbestudeerde Suid Afrikaanse varswater ongewerweldes. Daarenbowe, is hierdie studie
die eerste om genetiese en morfometriese differensiasie benede die genusvlak binne die
Phreatoicidea te ondersoek; sodoende word die metodologiese en teoretiese raamwerk vir die
herkenning van spesies en die akkurate beskrywing van diversiteit binne afsonderlike genera
van die Phreatoicidea geskep.
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The evolutionary history and taxonomy of the Kobus leche species complex of South-Central Africa in the context of palaeo-drainage dynamicsCotterill, Fenton P. D. 12 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: This multi-disciplinary study compiled taxonomic and biogeographical data to elucidate the
extant diversity of lechwe antelopes (Kobus leche complex), and reconstruct their evolutionary
history. Their diversification has been confined to wetlands across the south-central Africa
plateaux. Lechwes are specialist grazers in water meadow floodplains; these stenotopic habitat
requirements are invoked to explain why their evolution is atypical of terrestrial large mammals.
Combined analyses of morphological (171 adult males), genetic (208 genotyped individuals)
and palaeo-environmental datasets, revealed a recent (Middle Pleistocene) pulse of speciation in
the K. leche complex. Multivariate morphometric analyses revealed the presence of five distinct
groups that could be tied to the geography of the region. Furthermore, the genetic analyses
supported the existence of at least four of these lineages, which show significant population
separation at the level of the mtDNA control region. Most of the differences among populations
were confined to frequency differences among populations and Bayesian analyses strongly
suggest that the pattern obtained is the result of the retention of ancestral haplotypes with
limited female geneflow among the extant populations. Evolution of the five lineages identified
by the morphological and population genetic analyses were further investigated by making use
of additional genetic data (mtDNA cyt b, SPTNB, SRY, Protamine 1, and b-Fibrinogen) and a
subset of the samples. Topologies were largely unresolved due to the recent common ancestry
of the lineages. Following the Evolutionary Species Concept, which was motivated by a
philosophical review, five allopatric species could be recognized (anselli, kafuensis, leche,
robertsi and smithemani). A model of drainage evolution compiled disparate facets of biological
and geological evidence to detail interlinked histories of wetlands and their biota across the
south-central Africa plateaux. This wetland archipelago is recognized as a distinct
biogeographical unit in its own right - the Katanga-Chambeshi region. Evolutionary
diversification of lechwes represents a dominant biogeographical signal reflecting how the
aquatic biota have evolved in tandem with palaeo-drainage dynamics across this evolutionary
theatre. Delimitation of key events in lechwe and drainage evolution was refined by
archaeological dating of the Victoria Falls Formation, to decipher when the Zambezi river
eroded the Batoka gorge. Demographic expansion in K. leche s.s (early Middle Pleistocene)
corresponds to dessication of Palaeo-Lake Makakgadikgadi while more recent phylogeographic
signals correspond to the tenure of Palaeo-Lake Bulozi. These speciation events in the Middle
Pleistocene preceded peripatric speciation of K. kafuensis that accompanied the morphosis of
the Kafue Flats (from palaeo-lake to floodplain), when the Kafue River attained its modern
topology. The present study highlights that Lechwes represent a biota of evolutionary vibrant
clades, rich in endemic species. As ecologically-dominant species in wetlands, lechwes deserve priority conservation attention, which is challenged to perpetuate evolutionary and ecological
processes across an archipelago straddling five countries. / AFRIKAANSE OPSOMMING: Die multidisiplinêre studie bring saam taksonomiese en biogeografiese data om die evolusionêre
geskiedenis en huidige diversitiet van basterwaterbokke (Kobus leche kompleks) te verklaar.
Hulle diversifikasie is beperk to vleilande regoor die suid-sentraal Afrika plato.
Basterwaterbokke is gespesialiseerde grasvreters in grasvloedvlaktes; hierdie stenotipiese
habitatsvereiste word voorgehou om te verduidelik hoekom die evolusie van hierdie diere atipies
is vir terrestriële groot soogdiere. Gekombineerde analise van morfologie (171 volwasse
manlike diere), geneties (208 genotipes) en plaeo-omgewings datstelle toon aan dat daar ‘n
onlangse (middel Pleistoseen) pols van spesiasie plaasgevind het in die K. lechwe kompleks.
Multivariate morfometriese analyses het aangetoon dat vyf verskillende groepe diere bestaan
wat ook sin gemaak het op grond van geografiese ligging. Verdermeer, die genetiese analise het
die bestaan van ten minste vier van hierdie lyne geondersteun wat betekenisvolle bevolkings
isolasie vertoon het op die vlak van die mtDNA kontrole gebied. Meeste van die verskille tussen
bevolkings was beperk to frekwensieverkille tussen die bevolkings en Bayesian analise het sterk
aanduidings getoon dat die patroon wat gekry is die gevolg was van die behoud van
voorvaderlike haplotiepes met beperkte vroulike geenvloei tussen die huidige bevolkings.
Evolusie van die vyf lyne wat deur die morfologie en bevolkingsgenetika studies geidentifiseer
is was verder ondersoek deur gebruik te maak van addisionele genetiese data (mtDNA cytb,
SPTBN, SRY, Protamien 1, en b-Fibrinogeen) en ‘n subset van die monsters. Topologieë was
hoofsaaklik onopgelos as gevolg van die kort tyd tot die onlangse gemeenskaplike voorouer van
lyne. Deur die Evolusionêre Spesies Konsep aan te hang, wat gemotiveer is deur ‘n filosofiese
oorsig, is vyf allopatriese spesies herken (anselli, kafuensis, leche, robertsi and smithemani). ‘n
Model wat dreinerings evolusie voorstel het verskeie fasette van biologiese en geologiese
bewyse saamgvat om die verbindingsgeskiedenis van vleilande en hulle biota oor die suidsentraal
Afrika plato te beskryf. Die vleiland argipelago word herken as ‘n onafhanklike
biogeografiese eenheid in sy eie reg – die Katanga-Chambeshi streek. Evolusionêre
diversifikasie van basterwaterbokke verteenwoordig ‘n dominante biogeografiese sein wat
voortsel hoe die akwatiese biota ontwikkel het in tandem met die palaeo-dreinerings dinamika
in hierdie evolusionêre konsert. Die afbakening van sleutelgebeure in basterwaterbok en
dreinerigsevolusie is beter toegelig deur argeologiese datering wat gebasseer was op die
vorming van die Victoria Valle om te bepaal waneer die Zambezi rivier die Batoka skeurgroef gevorm het. Demografiese uitbreiding binne K. leche s.s (gedurende die vroë Middel
Pleistoseen) stem ooreen met die uitdroging van Palaeo-Meer Makakgadikgadi terwyl meer
onlangse filogeografiese syne ooreenstem met die ontstaan van Palaeo-Meer Bulozi. Hierdie
spesiasie gebeure in die Middel Pleistoseen het die peripatriese spesiasie van K. kafuensis
voorafgegaan wat die morfose van die Kafue Vlaktes vergesel het (van palaeo-meer na
vloedvlakte), toe die Kafue Rivier sy huidige vorm aangeneem het. Die huidige studie het
uitgelig dat basterwaterbokke verteenwoordig ‘n biota van evolusionêre energieke eenhede, ryk
aan endemiese spesies. As ‘n ekologiese dominante spesie in vleilande, moet basterwaterbokke
as ‘n prioriteit gesien word in bewaring, waar dit dan die geleentheid sal hê om voort te bou op
die evolusionêre en ekologiese prossese van die archipelago wat oor vyf lande strek.
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Bai use in forest elephants (Loxodonta africana cyclotis) : ecology, sociality & riskFishlock, Victoria L. January 2010 (has links)
Forest elephant (Loxodonta africana cyclotis) sociality is relatively little-studied due to the difficulties of making direct observations in rainforests. In Central Africa elephants aggregate at large natural forest clearings known as bais, which have been postulated to offer social benefits in addition to nutritional resources. This thesis explores the role of these clearings as social arenas by examining bai use within three main themes; ecology, sociality and risk factors. Seasonal changes in elephant use of the Maya Nord bai (Republic of Congo) are described, along with the demography of the visiting population. Elephant visit rate was highly variable; the number of elephants using Maya Nord in an observation day ranged from 0 to 117 animals. This variability was unrelated to local resource availability and productivity suggesting that bai use occurs year round. Elephants in Odzala-Kokoua do not show high fidelity to a single clearing; 454 elephants were individually identified and re-sighted an average of 1.76 times (range 1-10) during the twelve month study period. Previous bai studies have yet to quantify how elephants associate with one another within the bai area. This study examines socio-spatial organisation and associate choice using two measures of association within the 0.23 km2 bai area; aggregations (all elephants present in the clearing) and parties (elephants spatially co-ordinated in activity and movement) and distinguishes these from parties that range together (i.e. arrive and leave together). Social network analyses (SocProg) were used to describe inter- and intra-sexual multi-level organisation in the bai environment, and to illustrate the non-random nature of elephant aggregations and parties. Bais were shown to function as social arenas; female elephants showed active choice of certain associates and active avoidance of others when creating parties, whereas males were less discriminatory. Parties formed in the clearing (mean size= 3.93, SE= 0.186) were larger than ranging parties (mean size= 2.71, SE= 0.084) and elephants stayed for 50% longer in the clearing when they associated with individuals from outside their ranging party. Inter- and intra-sexual relationships were maintained within the clearing, and these are suggested to offer elephants essential opportunities for social learning. The patterning and nature of the relationships observed at the Maya Nord clearing indicates that forest elephants use a fission-fusion social structure similar to that of savannah elephants (Loxodonta africana africana); relationships are significantly structured by age- and sex- and underpinned by individual identity. Old experienced females hold key roles for forest elephants, and male relationships are superimposed on the network of female associations. Odzala-Kokoua elephants use bais to maintain their social relationships despite being highly sensitive to the anthropogenic risks involved in using these open areas. The results of this study suggest that forest and savannah elephants lie on the same social continuum, balancing social “pulls” to aggregate against the ecological “pushes” that force groups to fission. Previous models of savannah elephant sociality construct levels of association and social complexity upwards from the basic mother-calf unit (e.g. Wittemyer & Getz 2007). My results suggest that it may be more appropriate to consider elephant sociality and associations as in dynamic equilibrium between social and ecological influences acting at all levels of grouping, and to explicitly test how these underlie the opportunity costs that elephants are willing to pay in order to maintain social groupings.
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