## The Annals of Applied Probability

### The mean, variance and limiting distribution of two statistics sensitive to phylogenetic tree balance

#### Abstract

For two decades, the Colless index has been the most frequently used statistic for assessing the balance of phylogenetic trees. In this article, this statistic is studied under the Yule and uniform model of phylogenetic trees. The main tool of analysis is a coupling argument with another well-known index called the Sackin statistic. Asymptotics for the mean, variance and covariance of these two statistics are obtained, as well as their limiting joint distribution for large phylogenies. Under the Yule model, the limiting distribution arises as a solution of a functional fixed point equation. Under the uniform model, the limiting distribution is the Airy distribution. The cornerstone of this study is the fact that the probabilistic models for phylogenetic trees are strongly related to the random permutation and the Catalan models for binary search trees.

#### Article information

Source
Ann. Appl. Probab., Volume 16, Number 4 (2006), 2195-2214.

Dates
First available in Project Euclid: 17 January 2007

https://projecteuclid.org/euclid.aoap/1169065221

Digital Object Identifier
doi:10.1214/105051606000000547

Mathematical Reviews number (MathSciNet)
MR2288718

Zentralblatt MATH identifier
1124.05025

#### Citation

Blum, Michael G. B.; François, Olivier; Janson, Svante. The mean, variance and limiting distribution of two statistics sensitive to phylogenetic tree balance. Ann. Appl. Probab. 16 (2006), no. 4, 2195--2214. doi:10.1214/105051606000000547. https://projecteuclid.org/euclid.aoap/1169065221

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