Date of Completion
Protea, Proteaceae, Cape Floristic Region, functional traits, physiological traits, competition, coexistence
Kent E. Holsinger
Cynthia S. Jones
John A. Silander Jr.
Mark C. Urban
Field of Study
Ecology and Evolutionary Biology
Doctor of Philosophy
The Cape Floristic Region (CFR) in southwestern South Africa is a ‘biodiversity hotspot,’ hosting ~9,000 plant species in an area just over 90,000 km2. What is especially extraordinary about the CFR is that diversity here rivals that in many tropical forests, but it is not located in the highly diverse equatorial regions, making it difficult to identify the ecological and evolutionary processes that generate diversity and maintain it today. One way to better understand variation in species diversity across communities is to evaluate the distribution of the traits species’ possess. Specifically, trait variation within and across species can indicate how organisms interact with both their abiotic and biotic environments.
For my dissertation I take a trait-based approach to identify how trait variation could influence the performance of plants in the CFR, and how traits might mediate ecological interactions so as to minimize competition and promote coexistence. I focus on fynbos communities dominated by plants in the family Proteaceae, a family that represents much of the species diversity and abundance in local communities. I identify functional relationships between plant traits, performance, and fitness in a multivariate framework. I find that within species variation in traits related to performance might minimize fitness inequalities among co-occurring species, and that the covariance structure of traits might be important in leading to this outcome. Lastly, I show that trait differences among neighboring individuals are important for predicting performance in local neighborhoods by possibly minimizing competitive effects and also promoting adaptation to the local environment.
Nolting, Kristen, "What Makes a ‘Biodiversity Hotspot’ Hot? The Consequences of Trait Variation and Covariation for Individual Plant Performance and Species Coexistence in South African Proteaceae" (2020). Doctoral Dissertations. 2520.