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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21773 |
| Date | 12 1900 |
| Creators | Cotterill, Fenton P. D. |
| Contributors | Matthee, Conrad A., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xv, 424 leaves : ill. |
| Rights | Stellenbosch University |
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