Browsing by Author "Weighill, Benjamin"

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    Rodents and restios : rodents and the fates of Willdenowia incurvata (Restionaceae) seeds
    (Stellenbosch : Stellenbosch University, 2017-03) Weighill, Benjamin; Anderson, Bruce; Wossler, Theresa; Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology.
    ENGLISH SUMMARY: The biodiversity hotspot of the fynbos offers a “natural laboratory” to study species diversification, particularly in flowering plants. Often it is the interactions with the surrounding biotic or abiotic environments that drive this diversification. Interactions between plants and seed dispersers are just one of these interactions. In Chapter 1 of this thesis, recent studies pertaining to rodent assisted seed dispersal as well as other biotic seed dispersers in the fynbos were reviewed. This review emphasized the need for more studies of biotic seed dispersal in the fynbos despite the recent discovery of the first dung beetle assisted seed dispersal in the fynbos and the first investigations into seed dispersal by the Cape spiny mouse (Acomys subspinosus) and the hairy-footed gerbil (Gerbilliscus paeba). In Chapter 2, the seed dispersing and consumption behaviour of the hairy-footed gerbil (Gerbilliscus paeba) and the four-striped mouse (Rhabdomys pumilio) was investigated. It was confirmed that G. paeba dispersed seeds of Willdenowia incurvata (Restionaceae) at night and only consumed a small percentage of seeds in situ. In contrast, R. pumilio, which was only active during the day, only consumed and never dispersed seeds. In Chapter 3, the final data chapter, the effect of added elaiosomes from the closely related Willdenowia glomerata on rodents’ reactions to W. incurvata seeds was investigated. It was found that the added elaiosomes deterred both G. paeba and R. pumilio from interacting with seeds of W. incurvata. Both rodent species preferred seeds without elaiosomes attached. Gerbilliscus paeba consumed and dispersed more seeds without elaiosomes attached than seeds that had elaiosomes attached when given a choice between seeds the two seed treatments. Rhabdomys pumilio, which does not disperse seeds, also consumed more seeds without elaiosomes attached than seeds with elaiosomes attached. In the fynbos, one of the prevailing views regarding myrmecochory (seed dispersal by ants) is that it evolved as a response to heavy seed predation by rodents as seeds are rapidly removed from the soil surface by ants. However, the findings of this thesis suggest that not all rodents are purely seed predators and that some species may play an important role in seed dispersal. Consequently, it is more likely that myrmecochory evolved primarily to protect seeds from fire, through seed burial. Seed dispersal by rodents also involves burial and so it is likely that some rodents may perform a similar role to ants in protecting seeds from fire. From a biodiversity perspective, the further study and identification of new interactions of this kind are key in understanding the processes that shaped the diversity seen in the fynbos today. In addition, such interactions are critical for maintaining ecosystem function. Protection of this biodiversity hotspot becomes extremely challenging when species interactions are unidentified or unstudied, emphasizing the importance of this study for conservation efforts. From an evolutionary ecology perspective, how scatter-hoarding in rodents evolved, as well as the evolution of plant strategies that enhance dispersal by rodents are highly contested. Evidence from fynbos studies could provide further insights for drawing conclusions regarding the evolution of this plant-animal interaction.