Thesis (PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The order Macroscelidea has a strict African distribution and consists of two extant subfamilies, Rhynchocyoninae with
a single genus that includes three species, and the Macroscelidinae represented by the remaining three genera,
Elephantulus that includes 10 species, and the monotypic Macroscelides and Petrodromus. On the basis of molecular,
cytogenetic and morphological evidence, Elephantulus edwardii (Cape rock elephant-shrew), the only strictly South
African endemic species, was shown to comprise two closely related taxa. A new Elephantulus taxon, described here
is reported for the first time. It has a restricted distribution in the central Nama Karoo of South Africa. Apart from
important genetic distinctions, Elephantulus sp. nov. has several relatively subtle morphological characters that
separate it from E. edwardii.
Molecular sequences from the mitochondrial cytochrome b gene and the control region of E. edwardii sensu stricto
suggests the presence of a northern Namaqua and central Fynbos clade with four evolutionary lineages identified
within the latter. The geographic delimitation of the northern and central clades corresponds closely with patterns
reported for other rock dwelling vertebrate species indicating a shared biogeographic history for saxicolous taxa in
South Africa. Elephantulus rupestris (western rock elephant-shrew) and Macroscelides proboscideus (round-eared
elephant-shrew) are two taxa with largely overlapping distributions that span the semi-arid regions of South Africa and
Namibia. Based on mitochondrial DNA sequence data E. rupestris has a structured genetic profile associated with a
habitat of rocky outcrops compared to M. proboscideus that inhabits gravel plains, where the pattern is one of isolationby–
distance. Chromosomal changes, apart from heterochromatic differences, are limited to variation in diploid number
among elephant-shrew species. These range from 2n=26 (E. edwardii; E. rupestris; Elephantulus sp. nov.; E. intufi; E.
brachyrhynchus and M. proboscideus) to 2n=28 in both Petrodromus tetradactylus and E. rozeti to 2n=30 in E. myurus.
Cross-species chromosome painting (Zoo-Fluorescence in situ hybridization or zoo-FISH) of E. edwardii flow-sorted
probes that correspond to the five smaller sized autosomes (8-12) and the X chromosome showed no evidence of
synteny disruption among Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus and M. proboscideus, and
reinforced the G-banding observations underscoring the conservative karyotypes in these species.
A comprehensive phylogeny including all described elephant-shrew species is presented for the first time. A multigene
supermatrix that included 3905 bp from three mitochondrial (12S rRNA, valine tRNA, 16S rRNA) and two nuclear
segments (Von Willebrand factor [vWF] and exon 1 of the interphotoreceptor retinoid binding protein [IRBP]) was
analysed. Cytogenetic characters, previously described morphological, anatomical and dental features as well as
allozyme data and penis morphology were evaluated and mapped to the molecular topology. The molecular findings
did not support a monophyletic origin for the genus Elephantulus and suggests that both the monotypic Petrodromus
and Macroscelides should be included in Elephantulus. Molecular dating suggests that an arid-adapted
Macroscelidinae lineage dispersed from east Africa at ~11.5 million years ago via the African arid corridor to southwestern
Africa. Subsequent speciation events within the Macroscelidinae are coincidental with three major periods of
aridification of the African continent. / AFRIKAANSE OPSOMMING: Die orde Macroscelidea het ’n verspreiding beperk tot Afrika en sluit twee bestaande subfamilies in, die
Rhynchocyoninae wat drie spesies binne ’n enkele genus insluit en die Macroscelidinae verteenwoordig deur drie
genera, Elephantulus (10 spesies) en die monotipiese Macroscelides en Petrodromus. Gebaseer op molekulêre,
sitogenetiese en morfologiese bewyse, bestaan E. edwardii, tot op datum die enigste streng endemiese Suid-
Afrikaanse klaasneusspesie, uit twee nabyverwante taksa. Die nuwe Elephantulus takson, hierin beskryf, het ’n
beperkte verspreiding in die sentraal Nama Karoo van Suid-Afrika. Afgesien van belangrike genetiese bewyse wat die
beskrywing van die nuwe spesie ondersteun, word Elephantulus sp. nov. gekenmerk deur ’n aantal subtiele
morfologiese karakters wat dit onderskei van E. edwardii.
Binne E. edwardii sensu stricto, het mitochondriale molekulêre volgordes beduidende substruktuur aangedui regoor die
spesies se verspreiding. Die data het die teenwoordigheid van ’n noordelike Namakwa en sentrale Fynbos klade
aangetoon met vier evolusionêre lyne binne die laasgenoemde. Die geografiese skeiding van die noordelike en
sentrale klades stem grootliks ooreen met patrone in ander rotsbewonende vertebraat spesies, wat op ’n gedeelde
biogeografiese verlede in Suid-Afrika dui. Elephantulus rupestris (westelike klipklaasneus) en Macroscelides
proboscideus (ronde-oor klaasneus) is twee taksa met verspreidings wat grootliks oorvleuel in die semi-woestyn streke
van Suid-Afrika en Namibië. Mitochondriale DNS volgorde-bepaling dui op ’n gestruktueerde genetiese profiel binne E.
rupestris, geassosieer met ’n habitat van rotskoppies, in vergelyking met ’n isolasie-deur-afstand patroon wat M.
proboscideus, wat op gruisvlaktes aangetref word, karakteriseer. Chromosoom verandering, afgesien van
heterochromatiese verskille, is beperk tot ’n strukturele verandering van ‘n diploïede getal van 26 (E. edwardii; E.
rupestris; Elephantulus sp. nov.; E. intufi; E. brachyrhynchus en M. proboscideus) tot 2n=28 in beide Petrodromus
tetradactylus asook E. rozeti en 2n=30 in E. myurus. Kruis-spesies chromosoom fluoressent hibridisasie (“zoo-FISH”)
van die vloei-sorteerde merkers toegewys tot die vyf kleiner grootte outosome (8-12) asook die X chromosoom van E.
edwardii tot metafase chromosome van Elephantulus sp. nov., E. intufi, E. myurus, P. tetradactylus en M. proboscideus
het geen bewyse getoon van sintenie-verbreking nie en versterk G-bandbepaling waarnemings wat die konserwatiewe
kariotipes in hierdie spesies ondersteun.
‘n Volledige evolusionêre filogenie, verteenwoordigend van alle erkende klaasneusspesies, word vir die eerste keer
voorgestel. As sulks is ’n multigeen supermatriks wat gebaseer is op 3905 bp van drie mitochondriale (12S rRNA,
valien tRNA, 16S rRNA) en twee nukluêre segmente (Von Willebrand faktor [vWF] en ekson 1 van die
interfotoreseptor-retinoïed-bindende proteïen [IRBP]) ingesluit. As toevoeging, is nuwe sitogenetiese data, voorheen
beskryfde morfologiese, anatomiese en dentale karakters sowel as data van allosieme-analises en penis morfologie
ge-evalueer en nie-molekulêre ondersteuning aangedui op die molekulêre topologie. Die molekulêre bevindinge
ondersteun nie ’n monofiletiese oorsprong vir Elephantulus nie en stel voor dat beide die monotipiese Petrodromus en
Macroscelides ingesluit moet word in die genus Elephantulus. Molekulêre datering stel voor dat ’n dor-aangepasde
Macroscelidinae lyn versprei het vanaf oos Afrika ~11.5 miljoen jaar gelede deur die “droeë Afrika korridor” tot in suidwestelike Afrika. Verdere spesiasie gebeurtenisse binne die Macroscelidinae kan nouliks geassosieer word met
drie groot periodes van verdorring in Afrika.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21442 |
| Date | 03 1900 |
| Creators | Smit, Hanneline Adri |
| Contributors | Robinson, Terence J., Jansen van Vuuren, Bettine, 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 | English |
| Type | Thesis |
| Format | xix, 160 leaves : ill. |
| Rights | Stellenbosch University |
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