Browsing by Author "Rink, Ariella"

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    The evolution and prevalence of reproductive assurance in the genus Lachenalia
    (2013) Rink, Ariella; Verboom, Tony; Rodger, James
    Since its proposal by Darwin (1876), the concept of reproductive assurance (RA) has been much discussed, modified and tested. It is hypothesized to occur under pollen- and/or mate-limitation, each of which can arise in a multitude of manners, and RA itself takes many forms. Here its evolution and prevalence in the genus Lachenalia (Asparagaceae) is investigated. The genus exhibits many of the characteristics suggested in the literature to be associated with reproductive assurance, including intraspecific polyploids, vegetative reproduction and self-compatibility. Of the 27 study species, 20 were found to be self-compatible and four were capable of autonomous self-pollination. Pollinator-dependent species were found to have more attractive floral display structures. The five species exhibiting intraspecific polyploidy were all self-compatible. Offset production, known to occur in many Lachenalia species, was thought to exhibit a negative association with self-compatibility. No significant association, however, was found. A deeper understanding of the patterns of reproductive assurance in the genus requires study of the mechanisms enforcing self-incompatibility, and of the ecological and physiological correlates of reproductive assurance, is needed.
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    Friend or foe? The arrival of Stator limbatus (Bruchidae) in South Africa
    (2013) Rink, Ariella; Hoffmann, John
    Stator limbatus is a generalist seed-feeding beetle (Coleoptera: Bruchidae) whose natural range extends from the southern USA to Latin America. Individuals have recently been collected in the Western Cape province of South Africa in seeds of the invasive alien plant species Acacia mearnsii and A. cyclops. This study conducted a preliminary examination of its oviposition preference, and development on, a number of indigenous and invasive alien Acacia species and the invasive alien Paraserianthes lophantha (all Fabaceae). Oviposition preference appears to be for larger seeds but A. ataxacantha was found to be the only indigenous host suitable for larval development.