Evolution of species interactions: finding meaning in community-level phylogenetic patterns

Rachel M. Germain and Benjamin GilbertDepartment of Ecology & Evolutionary Biology, University of Toronto

“As species of the same genus usually have some similarity in habits and structure, the struggle will generally be more severe between species of the same genus.”

C. Darwin, 1859

1946: “…the thing that stands out (in ecological surveys) is the high percentage of genera with only one species present.”

84% of plant genera only have a single species represented locally

Elton et al. 1946 J of Animal Ecology

Environmental filteringCompetitive interactions

Over-dispersion Under-dispersion

Webb et al. 2002 Annu Rev Ecol Syst

…but evidence is mixed in natural systems

Anderson et al. 2011 J of Ecology

= sig over- or under- dispersion

= non-sig over -or under- dispersion

Environmental filteringCompetitive interactions

Mechanistic inferences are contingent on trait conservatism

Environmental filteringCompetitive interactions

Mechanistic inferences are contingent on trait conservatism

Environmental filteringCompetitive interactions

Mechanistic inferences are contingent on trait conservatism

Environmental filteringCompetitive interactions

No phylogenetic signal Over-dispersion

Mechanistic inferences are contingent on trait conservatism

Phylogenetic conservatism varies from trait-to-trait

Cavender-Bares et al. 2006 Ecology

Rates of trait evolution vary widely across lineages

Rate of trait evolution

Venditti et al. 2011 Nature

Implications for taxonomic scale dependency

Cavender-Bares et al. 2006 Ecology

Quercus Ilex Pinus

Biogeographic history influences trait evolution and species interactions

Phylogenetic patterns may be unpredictable between species that have not coevolved through evolutionary time

Are phylogenetic patterns useful for understanding ecological processes?

• Problems:– lack of trait conservatism• between traits• between lineages

– taxonomic scales– biogeographic history

Empirical examples?

My MSc workMediterranean annual plants from

California and Spain

Pairwise competition trials based on:– phylogenetic distance– biogeographic origin

How do species differences, biogeography, and the environment combine to regulate phylogeny-coexistence relationships?

How do species differences, biogeography, and the environment combine to regulate phylogeny-coexistence relationships?

Acknowledgements

Marc Cadotte Chris Blackford Natalie JonesJason Weir Yvonne Chan

Alicia Hou S&S SeedBruce Hall HerbiseedAndrew Petrie