Browsing by Subject "seed dispersal"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Open Access
    Dispersal of semi-fleshy fruits to rock crevices by a rock-restricted rodent
    (2017) White, Joseph DM; Midgley, Jeremy J
    Seed dispersal allows successive generations of plants to be mobile in space and time. Heeria argentea’s unusual fruit and its ubiquity in extremely rocky habitats, suggests that this tree requires a specialist disperser. We therefore investigated the dispersal ecology of H. argentea and Hartogiella schinoides. We found M. namaquensis rapidly removed H. argentea and H. schinoides fruits, moving them short distances within and between rock outcrops, and consumed only the pericarps. Birds were observed consuming H. schinoides, but not H. argentea fruits, suggesting M. namaquensis is its sole, specialist disperser. Most H. argentea seeds (65%) with removed pericarps germinated successfully, while intact fruits did not. We show rock outcrops represent fire refugia, allowing H. argentea trees to grow to large sizes, with small stems and a co-occurring, wind-dispersed tree, Widdringtonia nodiflora found away from these sites. This rodent–tree mutualism is perhaps the clearest global example of directed dispersal and shows that these endemic trees are highly adapted for survival in the southwestern Cape habitat and are not tropical relicts.
  • Thumbnail Image
    Item
    Open Access
    Small mammal community structure (Rodentia: Muridae) in Punda Maria, Kruger National Park, South Africa : Causes and consequences
    (2008) Scholtz, Rheinhardt; Midgley, Jeremy J; Keith, Mark
    The population dynamics of small mammal populations in Punda Maria, Kruger National Park, South Africa was investigated with respect to community size and structure, seed predation and dispersal of several trees. Species populations, community structure and habitat attributes were measured at six sites comprising of 3 habitat types (2 sites per habitat); namely Acaciagrassland, North-facing and South-facing sloped sites. Seasonal variation was investigated at the Acacia sites during late summer (April) and winter months (July). Five habitat attributes were measured; percentages of total cover and herbage, plant litter depth (cm), height of dominant vegetation type measured (m) and edaphic condition were recorded at 15 randomly selected traps per site. Almonds (Prunus dulcis), baobabs (Adansonia digitata), mopane (Colophospermum mopane), and Acacia tortilis seeds were used in the predation and dispersal experiment. North- and South-facing sites were dominated by Aethomys sp. while Acacia sites were dominated by Mastomys natalensis. Seed predation was high at the North-facing slopes, with a significant difference in predation on A. tortilis seeds. Seed dispersal activity was low; no , scatter hoarding was identified; only larder hoarding was observed by Aethomys sp. and M. natalensis at North-facing sites and Acacia sites respectively. Trampling by megaherbivore activity impacted vegetation structure and has negatively affected rodent population and ground activity, particularly at the Acacia sites.
  • Thumbnail Image
    Item
    Open Access
    Two dung beetle species that disperse mimetic seeds both feed on eland dung
    (2016) Midgley, Jeremy J; White, Joseph DM
    Abstract Scarabaeus spretus zur Strassen was observed to roll and bury Ceratocaryum argenteum (Restionaceae) seeds in the sandplain fynbos of the Potberg area of the De Hoop Nature Reserve, South Africa. This species is the second dung beetle species found to be deceived by the faecal mimicry of C. argenteum seeds – the first species being Epirinus flagellatus. An isotopic analysis suggests that both these dung beetle species most likely feed on eland (Taurotragus oryx), not bontebok (Damaliscus pygargus pygargus), dung. Thus the model in this mimicry is eland dung; this interaction suggests large herbivores are an integral part of this fynbos.