Integrating coevolution into the tree of life 0

Integrating coevolution into the tree of life 0 Scott L. Nuismer

What is coevolution? Species 1 Species 2 Coevolution: Reciprocal evolutionary change in interacting species (Janzen, 1980) "Thus I can understand how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted to each other in the most perfect manner, by the continued preservation of all the individuals which presented slight deviations of structure mutually favourable to each other. " — Charles Darwin, The Origin of Species

The importance of coevolution Much of what we know about coevolution comes from mathematical models

A key assumption of coevolutionary theory

A key assumption of comparative methods

The current state of affairs Coevolutionary theory ignores phylogeny Phylogenetic comparative methods ignore coevolution

This raises two important questions Question 1: Do coevolution and phylogeny interact to shape contemporary trait values? Question 2: Can we predict contemporary rates of interaction? Our goal is to use a mathematical model to answer these questions

Merging coevolution and evolutionary history Species 1 Species 2 +

A general modeling approach First time interval Second time interval Third time interval (no coevolution) (2 -way coevolution) (3 -way coevolution) Our approach will be agnostic with respect to the process of speciation

How do traits mediate interactions? Model 1: Phenotype Differences How do traits mediate interactions Best suited for interactions that depend on interference competition

How do traits mediate interactions? Model 2: Phenotype Matching How do traits mediate interactions Best suited for interactions that depend on exploitation of shared resources

Predicting trait coevolution Individual fitness Random encounters among individuals Gaussian trait distributions Classical quantitative genetics

Coevolutionary dynamics on a star phylogeny Phenotype differences How do traits mediate interactions Phenotype matching How do traits evolve?

Integrating evolutionary history: Phenotype differences How do traits mediate interactions Best suited for interactions that depend on interference competition

Integrating evolutionary history First interval: After speciation Before speciation 0

Integrating evolutionary history After speciation Second interval: Before speciation 0

Integrating evolutionary history Third interval: 0 This result can be easily generalized for any phylogeny

Coevolution and phylogeny do not interact

Phylogeny explains phenotypic similarity

Coevolution explains expected trait values

Contemporary interactions can be predicted Expected outcome? How do traits mediate interactions Expected asymmetry? How do traits evolve?

Integrating evolutionary history: Phenotype matching How do traits mediate interactions Best suited for interactions that depend on exploitation of shared resources

Integrating evolutionary history First interval: After speciation Before speciation 0

Integrating evolutionary history After speciation Second interval: Before speciation 0

Integrating evolutionary history Third interval: 0 Unfortunately, this result cannot easily be generalized

Coevolution and phylogeny interact

Phylogeny creates a template of phenotypic similarity

And coevolution modifies this template

Contemporary interactions can be predicted Expected intensity of competition (without coevolution) Expected intensity of competition (with coevolution) If we also have information about the historical strength of coevolution

Conclusion 1: Coevolution leaves a signature

Conclusion 2: Interactions can be predicted We can predict asymmetries How do traits evolve? We can predict intensity

Acknowledgements Funding National Science Foundation Luke Harmon