Proposal Phylogenetic Approaches to the Study of Niche Evolution
Workshop Proposal: Center for Population Biology Research Fellowship D. Luke Mahler Harvard University
A question of longstanding shared interest to ecologists and evolutionary biologists is “How do ecological niches evolve?” Theories and models of niche evolution have played central roles in studies of community ecology, biogeography, speciation, adaptive radiation, and climate-change biology for over half a century. Phylogenies provide a powerful framework for investigating niche evolution over macroevolutionary timescales, and in recent years there has been a dramatic rise in the development of new phylogenetic tools for this area of study. In parallel, recent decades have seen a surge in the availability of detailed spatial data on climate and species distributions, which may be stored and analyzed in geographic information systems. Geographic-occurrence data and spatial-climatic data may be used to construct environmental niche models (ENM) for species, and phylogenetic methods may be used to test hypotheses about the evolution of the climatic niche in clades. Phylogenetic methods may also be used to test hypotheses about the evolution of phenotypic traits involved in resource utilization and competition (e.g., ecomorphological traits). Together, these phylogenetic approaches provide new ways to investigate the evolution of Hutchinson’s multidimensional niche among related organisms. This workshop will introduce participants to state-of-the art techniques for the phylogenetic study of niche evolution, with the goal of merging ENM and trait-based techniques for more robust approaches to this problem. During the first session, I will introduce several popular models used in ENM and trait evolution studies, including the ‘maximum entropy’ environmental niche model, and the ‘Brownian motion’2, ‘Ornstein Uhlenbeck’3, and ‘lineage diversity’4 models of trait evolution. For each model, I will clearly outline its assumptions, limitations, and most common applications. In the second session, I will teach participants how to build an ENM and test a niche-conservatism hypothesis using distribution data for hylid frogs and the software programs ‘Maxent’1 and ‘ENMTools’5. In the third session, participants will test a hypothesis about competitively driven adaptive radiation using limb length data for Caribbean anoles and the ‘R’ software package. The content of each of these sessions will be based in part on my experiences as a teaching fellow for a graduate course in niche evolution. This workshop will (1) outline the power and limits of phylogenetic approaches to niche evolution, and (2) provide hands-on experience testing hypotheses using real data and current software. The goal of this workshop is for participants to feel comfortable employing phylogenetic approaches to investigate niche evolution in their own systems of interest, regardless of their previous experience with these methods and software.
1. Phillips et al. 2006. Ecol. Model. 190:231-259.
2. Felsenstein 1985. Am. Nat. 125:1-15.
3. Hansen 1997. Evolution 51:1341-1351.
4. Mahler et al. 2010. Evolution 64:2731-2745.
5. Warren et al. 2008. Evolution 62:2868-2883.