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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Multivariate analysis of selected honeybee populations in Africa

Radloff, S E (Sarah E.), 1948- January 1996 (has links)
Morphometric characters and sting pheromones of worker honeybees, Apis mellifera Linnaeus were analysed by multivariate methods to characterise selected honeybee populations along five transects in Africa at a meso-scale level of sampling distance resolution. In some, but not all, areas pheromonal clusters were found to be coincident and concordant with the morphometric clusters, thus indicating that different honeybee traits have dispersed variably among populations. All transects were found to contain areas of significantly high variance. High intracolonial variance was taken to indicate localised genetic variation coupled with out-cross matings. Centroids of high intercolonial variance occured at and between cluster boundaries and were typical of transitions between, and rainfall-temperature discontinuities within, ecological-climatological zones, hence areas of ecological instability. Principal component and stepwise discriminant analysis yielded three morphometric clusters corresponding to A. m. sahariensis and A. m. intermissa in Morocco and to A. m. iberica (with three biometric populations) in Spain, but no pheromone clusters. The combined morphometric and pheromonal variance spectra indicated regions of natural hybridisation along a Sahara-Pyrenees transect. In the Horn of Africa, discrete and statistically homogeneous populations were identified: A. m. jemenitica, A. m. bandasii, A. m. sudanensis in Ethiopia and an unclassified group in southwestern Somalia. Areas of high intercolonial variance were interpreted as zones of hybridisation between the populations. Along a transect in west central Africa, three distinct homogeneous populations and two zones of hybridisation were found. These bees were designated as A. m. adansonii whose area of distribution was intruded by an un-named mountain group of bees and a third group, A. m. jemenitica. The delineation of the hybrid zones was supported by intercolonial variance spectra and these significant asymmetries were found to be coincident with transitions between the ecological-climatological zones. In southwestern Africa, two discrete homogeneous populations and a zone of hybridisation between them were identified: A. m. scutellata in northern South Africa and southern Namibia and A. m. adansonii in northern Namibia. Along a transect in the southeastern woodland savanna of Africa, three discrete populations were classified: A. m. litorea in Mozambique, A. m. scutellata in Zimbabwe and A. m. adansonii in northwestern Zambia. A zone of introgression between the last two subspecies occured in south-central Zambia and in the Zambezi valley.
2

Phylogenetic systematics of Scrapter (Hymenoptera: Anthophila: Colletidae).

Davies, Gregory Bernard Peter. January 2006 (has links)
Scrapter Lepeletier de Saint-Fargeau & Audinet-Serville, 1828 (Hymenoptera: Aculeatea: Anthophila: Colletidae) is a genus of solitary bees largely endemic to southern Africa. This dissertation investigated the phylogenetic systematics of the genus. Eleven new species of Scrapter are described, principally from the Succulent Karoo biome of South Africa, bringing the total number of species in the genus to 42. An updated dichotomous key to facilitate identification is provided. The previously unknown females of S. albifumus Eardley and S. amplispinatus Eardley are also described. The genus is recorded from outside southern Africa for the first time with the collection of S. nitidus (Friese) in Kenya. This constitutes a significant range extension of the genus. The taxonomic status of five species described by Cockerell in 1944, and subsequently overlooked, is addressed. They are all found to be synonyms of other Scrapter species, except one, which is found to be a Ctenoplectrina species (Apidae: Apinae: Ctenoplectrini). The new synonymies are: S. subincertus Cockerell = S. niger Lepeletier de Saint-Fargeau & Audinet-Serville; S. brunneipennis Cockerell = S. niger Lepeletier de Saint-Fargeau & Audinet-Serville; S. merescens Cockerell = S. leonis Cockerell; S. sinophilus Cockerell = S. algoensis (Friese). Scrapter ugandica Cockerell becomes Ctenoplectrina ugandica (Cockerell) as a new combination. Investigation of selected morphological features (e.g. postmentum, facial fovea, galea) revealed much diversity in Scrapter. The monophyly of Scrapter is not supported by unambiguous apomorphies, but is defensible by the congruence of various qualitative characters (e.g. premental fovea, T2 fovea, hindleg and sternal scopa in [females], two submarginal cells). A cladistic analysis using 25 morphological characters recovered numerous most parsimonious trees under both equal- and successive-weighting. To aid in resolution, several taxa known from only one sex or from very limited material, and with many unknown states, were deleted from the matrix. Analysis using this reduced matrix under equal- and successive-weighting resulted in better resolution, although with low consistency index values. Several subclades were common to both cladograms, and likely represent monophyla. The low consistency indices and general lack of unique synapomorphies upholding these subclades, however, dictated against making any classificatory re-arrangements. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

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