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A conceptual and statistical framework for adaptive radiations with a key role for diversity dependence
Rampal S Etienne1, Bart Haegeman
1Community and Conservation Ecology, Centre for Ecological and Evolutionary Studies, University of Groningen, The Netherlands. r.s.etienne@rug.nl
The American Naturalist
|September 15, 2012
Summary
This study introduces a new framework for adaptive radiations, showing how key innovations can decouple diversification dynamics. This approach helps understand ecological opportunity and limits in macroevolution.
Area of Science:
- Macroevolutionary biology
- Phylogenetics
- Ecology
Background:
- Diversity dependence shapes adaptive radiations, causing deceleration and initial diversification pulses.
- Key innovations, including novel traits and environments, can decouple diversification dynamics between clades.
- Understanding the interplay of ecological opportunity and limits is crucial for macroevolutionary studies.
Purpose of the Study:
- To propose a new framework for studying adaptive radiations within the context of diversity-dependent diversification.
- To develop a likelihood-based inference method for testing the decoupling of diversity dependence using molecular phylogenies.
- To analyze the North American clade of the legume tribe Psoraleeae to illustrate the framework's application.
Main Methods:
- Developed a likelihood-based inference method to test for decoupling of diversity dependence.
- The method accommodates incomplete phylogenies and identifies timing and affected diversification parameters.
- Applied the method to the molecular phylogeny of the Psoraleeae North American clade (47 extant species).
Main Results:
- The analysis revealed decoupling of two Pediomelum subgenera from other Psoraleeae lineages, associated with the first diversification rate shift.
- A second, negative diversification rate shift was attributed to protracted speciation, implying nonzero extinction rates.
- The framework successfully identified when decoupling occurred and which diversification parameters were affected.
Conclusions:
- The proposed framework offers a novel perspective on macroevolution, integrating ecological opportunity and diversity dependence.
- Key innovations can lead to distinct diversity-dependent dynamics in innovative clades versus ancestral clades.
- Ecological opportunity (new traits/environments) and ecological limits (diversity dependence) are interconnected and cannot be studied in isolation.
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