The past thirty years have seen a tripling in the number of Xenopus species recognized. The complexp atterno f speciesd istributiond emonstrateadc rossth es ub-Sahararna nger eflectse cological constraintsi mposedb y climate conditionst hroughoutt he Pleistocenea, nd highlights a numbero f areas of specific biogeographic interest. Although previous application of comparative osteology as a method for phylogenetic investigation at the species level in Anura has been limited, the approach, adopted in this study, has proven to be highly informative in its application to specific taxonomic studies. An overview of osteologicalc haractersin the type specieso f the genusX enopusi s presented for the first time and forms the basis for subsequent osteology-based species descriptions. Results implicate two tetraploids, X 1. victorianus and X fraseri in the hybrid origin of an octoploid species pair, X. wittei and X. vestitus in the Central African highlands. Existing ambiguity surrounding the taxonomic distinction between two cryptic taxa, also living in these highlands, XL victorianus and X 1. bunyoniensis is considered. Osteologically, the two are distinct. Corroboration for the sub-division of X. muelleri into eastern and western forms is provided by studies on comparative osteology and mating-call, amongst others. The taxonomic significance of thesef indings is overshadowedh owever,b y evidenceo f widespreadh ybridization and introgression with distantly relatedX . 1.l aevis in the southeasternp art of the X. muelleri range. Although only two species are currently known from Ethiopia, evidence of morphology indicates that museum collections of X. clivii comprise at least two distinct forms, one appearing to be intermediate between the two Xenopus sub-genera. Furthermore, osteology reveals that X largeni also straddles this taxonomic boundary, casting doubt on the robustness of this phylogenetic division. Results are consistent with recent findings from molecular-based phylogenies, qualifying the use of comparative osteology as an informative method for investigation of evolutionary interactions
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:268526 |
| Date | January 2002 |
| Creators | Henderson, Anna Catrin |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1983/8ba52130-eeca-4b4c-9722-2129646b12b1 |
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