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Niche partitioning: African savanna species coexistence reviewed

Lijcklama à Nijeholt, and C, (2017) Niche partitioning: African savanna species coexistence reviewed. Research Project 2 (major thesis), Ecology and Evolution.

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Abstract

The incredible high biodiversity of Africa has been a subject of much discussion. The assemblages of large mammalian herbivores on this continent are usually comprised of about 10-25 species, coexisting on a limited range of resource types. A much-asked question is thus, how can so many species coexist without competitively excluding each other? A compelling explanation emerges through the differing body sizes of the species, that span three orders of magnitude. The Jarman-Bell principle states that large endotherms can consume low quality forage, provided there is sufficient quantity, while smaller species consume high quality forage in smaller quantities. This is a much-studied principle, however there is still much debate and uncertainty on the precise mechanisms involved in niche partitioning amongst African savanna herbivores. This paper provides a comprehensive review of the most relevant literature existent on niche partitioning, giving a good overview of what should be taken into account in future studies. Novel methods, such as GPS collaring and DNA metabarcoding, are discussed and gaps in the research pointed out. A reminder is given on the importance of ecosystem heterogeneity, that is under threat due to human impacts. Found was that the diet quality of the species is important in niche partitioning as there is a negative relationship between diet quality and body mass. However, this pattern differs according to the digestive adaptation of the species. Non-ruminants, compared to similar sized ruminants, can consume lower quality food leading them to occupy a more diverse habitat. Additionally, body size has no clear influence on niche partitioning in non-ruminants. Body size is also not related to diet type (browser/grazer). Furthermore, sometimes there is more diet similarity across grazer and browser guilds than within them. Larger species generally have larger mouths, allowing them to consume higher quantities of the lower quality forage they need to meet their nutritional requirements, with exception of the megaherbivores. Additionally, studies should encompass both the dry and the wet season, as competition is reduced in the wet season, making niche partitioning less apparent. Next to resource limitation, predation pressure also plays a vital role, which is widely ignored. New methods such as GPS collaring allow for conclusions at a finer habitat scale, while DNA metabarcoding permits identification of the vegetation being consumed at the species-level. Future research should take all of these mechanisms into account to get a clear picture of niche partitioning. The increasing human population and its impacts bring these delicate interactions into danger, reducing ecosystem heterogeneity and consequently biodiversity. Understanding the mechanisms of niche partitioning, and how humans impact them, should be a priority in African savanna research.

Item Type: Thesis (Research Project 2 (major thesis))
Degree programme: Ecology and Evolution
Thesis type: Research Project 2 (major thesis)
Language: English
Date Deposited: 15 Feb 2018 08:27
Last Modified: 15 Feb 2018 08:27
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/14975

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