Browsing by Subject "Rodent pollination"

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    Rodent pollination in Protea nana
    (2009) Biccard, A.; Midgley, J. J.
    Floral morphology, late winter flowering time and a distinct yeasty odour in Protea nana suggest that it is adapted for rodent pollination. To test this hypothesis, rodents were trapped in a stand of P. nana, examined for presence of pollen (on their noses and in their scats) and then observed in the laboratory for pollination behaviour. Inflorescences were placed in wire and shade-cloth exclosures and seed-set compared to controls in the field. Otomys irroratus, Aethomys namaquensis, Rhabdomys pumilio and Myomyscus (Praomys) verreauxi were captured and all tested positive for the presence of protea pollen. All, except O. irroratus, displayed legitimate pollination of P. nana. Myomyscus verreauxi was regarded as the most competent pollinator as it displayed superior climbing ability in comparison to the other rodent species. R. pumilio sometimes displayed highly destructive behaviour of P. nana inflorescences and is the likely explanation for the observed 20% reduction in average number of inflorescences per plant over a two month period. Seeds per inflorescence were lowest in shade-cloth covered inflorescences (total pollinator exclusion), but not significantly lower in wire exclosures which provided access for insects. A high percentage of sugar (29.4% by weight) in the nectar of P. nana is similar to known rodent pollinated species. We conclude that P. nana is at least partially rodent pollinated.
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    Variation in seed set amongst populations of a redent pollinated geophyte, Colchicum coloratum
    (2009) Kleizen, C; Midgley, J J; Johnson, S. D.
    Agricultural activities around the rural village of Nieuwoudtville in the Succulent Karoo region of South Africa has lead to the confinement of many plant and animal species to fragmented patches of relatively untransformed habitat. The geophyte Colchicum coloratum subsp. coloratum (Colchicaceae) was studied in five patches of variable size in and around Nieuwoudtville. This species is dependent on rodent visitation for seed production. The influence of variation in population size and plant size on seed set was investigated, as well as whether there is pollen limitation in this species. A pollen-supplementation experiment indicates that there is pollen limitation in C. coloratum, and that much of the natural seed set could be the result of pollinator-mediated selfing. The five populations appeared to have different rodent abundances, however, neither population size nor the abundance of rodents in the area have an effect on seed set. This suggests that the mutualism between C. colchicum and its rodent pollinators is robust, and that habitat fragmentation in Nieuwoudtville has not yet affected the seed production of this geophyte.