A Thesis Submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in Fulfillment of the Requirements for the Degree of Doctor of
Philosophy. October, 1995. / The methods of vicariance biogeography are in general rendered equivocal by
widespread taxa. Standard methods resort to ad hoc assumptions in their treatment
of widespread cases, and the results are always si bordinate to the addition of new
data on endemic sister taxa. I introduce an alternative method for the analysis of
widespread taxa based on the vicariance model. The method requires first the
development of a habitat model for each species included in the analysis. I analyse
the actual and "potential" distributions by cladistic methods, employing a weighting
system designed to factor out the influence of ecological similarity. The resolution
of the inferred area relationships is seen to increases with the application of the
weighting-compelling evidence that the pattern reflects historical relationship. I
review current approaches to the modelling of habitats. All seem to be based on an
ecological model of equilibrium, where the limits of actual species distributions are
thought to reflect habitat, as if historical contingency played no significant part in
determining the shape of real distributions. Under this model all approaches are
group discrimination methods. I reject these methods and develop a new method
based on principal component analysis. I analyse the distributions of all extant
endemic African antelope and derive probability surfaces for each species. The
model output can be interpreted as species distribution free oflHstory-its
potential distribution. This is different from assuming that actual distributions are
free of history. Areas oferdemism are seen to be historical entities, not simply
distributional ones, and the resulting area cladograrn is interpreted as the
hierarchical pattern of endemism. A striking feature of the inferred pattern of
endemism is the intersection of an east-west equatorial biota, and a north-south
savanna biota. These bisect in East Africa at the centre of highest antelope
diversity. I predict that this feature will be seen to be the most persistent feature of
endemic structuring in other African taxa with high East African diversity. / AC2017
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/22045 |
| Date | January 1995 |
| Creators | Caithness, Neil |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
Page generated in 0.0025 seconds