# PLG

## Seminar

### Ranked tree shapes, shuffles, and a new test for neutrality

Gernhard, T (Munchen)
Wednesday 19 December 2007, 10:00-10:20

Seminar Room 1, Newton Institute

#### Abstract

Phylogenetic tree shapes are an established object of study, and have proven useful for testing macroevolutionary hypotheses. However, tree shapes are typically considered without branch length information, which eliminates a considerable amount of useful data. We propose the use of ranked'' phylogenetic tree shapes-- tree shapes such that the order of diversification events is specified-- to test macroevolutionary hypotheses. We describe two classes of null models on ranked tree shapes, and then propose a test for deviation from these models. In particular, our test rejects the null hypothesis when relative rates of diversification for two daughter clades change over time. Thus, we consider the test as looking for evidence of bursting'' diversification on one hand, or refractory'' diversification on the other. Our test rejects neutral evolution for a sample of sequences of the Hepatitis C virus which will be discussed.

#### Video

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