Browsing by Author "Malan, Michelle"

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    Intraspecific variation in Erica coccinea
    (2013) Malan, Michelle; Midgley, Jeremy J; Van der Niet, Timotheus
    The genus Erica is the most specious in the Cape Floristic Region, with a large range of habitats, pollination syndromes and fire survival strategies. Erica coccinea, like many other Cape Erica species, has high intraspecific variability between populations. In addition to variability in floral characteristics such as colour, this species includes two distinct regeneration forms: a resprouter form which survives fire by resprouting from dormant buds in a swollen lignotuber, and a seeder form which does not survive fire, but whose populations regenerate from fire-triggered seed germination. Previous studies have shown that these two regeneration forms are genetically determined and this dissertation investigates further the differences in floral morphology, phenology, fecundity and genetic relatedness across 29 populations. Results show patterns of seeder individuals investing more effort into nectar and seed production than resprouters and differences in flower colour and flowering phenology between the two fire life history strategies. A PST-FST analysis, comparing genetic variability to variability in floral traits shows a strong selective force working on anther length in the seeder form. A complete separation of flowering phenology between seeder and resprouter individuals in 'mixed' populations where the two forms co-occur leads to speculation that this might be a case of incipient speciation.
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    Self-pollination in the genus Erica
    (2009) Malan, Michelle; Midgley, Jeremy J
    The ability of flowers to self-pollinate was investigated in eight species of the diverse Erica genus. Self-pollination was found to occur in five out of the eight species, with mainly bird pollinated species having a high degree of selfing. The use of a broken anther ring as an indication of visitation and pollination of the flowers was also investigated and it was found that two species are potentially useful in this regard. An inverse relationship between the degree of selfing and near neighbour distance was found across the species. The resprouting Erica cerinthoides was found to have a UV signal, it also had the most dispersed population, highest nectar sugar concentration and a high degree of self-pollination. Erica paludicola, which is an endemic that occurs in only one other population on the Cape Peninsula, had the highest degree of self-pollination. I speculate that the high degree of selfing in Erica is one of the reasons the genus is so diverse, and that the ability to self will preserve this diversity in the face of increasing habitat destruction and fragmentation, at least temporarily.
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