Browsing by Author "White, Joseph DM"

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    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.
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    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.