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Abstract Detail

Ecological Section

Mitchell, Nora [1], Moore, Timothy E. [2], Holsinger, Kent E. [2].

Functional traits in evolutionary radiations and the origin of trait-environment associations.

The extreme levels of species diversity found in evolutionary radiations present a unique opportunity to study the role of functional traits in plants. Differences in traits both among and within species can reflect patterns of distribution, local adaptation, and phenotypic plasticity in response to contrasting environmental conditions. Relationships between traits and environment can thus reflect several different processes, and patterns can speak to different physiological or life-history strategies. Since there is non-independence among both traits and environment, it is necessary to take into account the covariation between variables to understand whole-plant response. Here, we use a Bayesian multi-response model to identify trait-environment relationships in two evolutionary radiations in the fynbos biome of the Cape Floristic Region (CFR) of South Africa, taking into account covariation amongst traits, climate variables, and also controlling for phylogenetic relationships. The genera Protea and Pelargonium are morphologically and evolutionarily diverse radiations that typify the CFR, which is characterized by high levels of biodiversity and ~70% endemism and boasts over 9,000 plant species. The CFR is also characterized by environmental heterogeneity, topographical complexity, and gradients in both the amount and seasonality of rainfall, making it an ideal system to study the relationships between traits and environment. We show that two clades, which are very different in form, inhabiting the same geographic extent, display some similar trait-environment associations, while differences in associations might reflect alternate life history strategies. Our multiple-response model performs much better than individual response models (evaluated by DIC scores), providing evidence for the necessity of incorporating the non-independence of traits in assessing plant strategy. Our results caution that global patterns, such as the worldwide leaf economics spectrum (LES), may not hold up at the within-biome, within-clade level, and when covariance among both traits and environments are considered. Conclusions regarding the associations between traits and environment are complex, and must take into account whole-plant level characteristics. We surmise that the environmental heterogeneity and high levels of diversity in the fynbos reflect complicated patterns and are often lineage-specific. It remains to be determined whether these relationships reflect adaptation, how they may have contributed to diversification, and the implications for species distribution and persistence given future climate change.

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Related Links:
Parallel Evolutionary radiations in Protea and Pelargonium in the Greater Cape Floristic Region

1 - University Of Connecticut, Ecology & Evolutionary Biology, 75 North Eagleville Rd, U-3043, Storrs, CT, 06269, USA
2 - University of Connecticut, Ecology & Evolutionary Biology, 75 North Eagleville Rd., U-3043, Storrs, CT, 06269, USA

evolutionary radiation
plant ecology
trait-environment association
functional traits
Bayesian modeling.

Presentation Type: Oral Paper:Papers for Sections
Session: 24
Location: Clearwater/Grove
Date: Tuesday, July 29th, 2014
Time: 11:00 AM
Number: 24004
Abstract ID:236
Candidate for Awards:Ecological Section Best Graduate Student Paper

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