## The Annals of Applied Probability

### Mutations on a random binary tree with measured boundary

#### Abstract

Consider a random real tree whose leaf set, or boundary, is endowed with a finite mass measure. Each element of the tree is further given a type, or allele, inherited from the most recent atom of a random point measure (infinitely-many-allele model) on the skeleton of the tree. The partition of the boundary into distinct alleles is the so-called allelic partition.

In this paper, we are interested in the infinite trees generated by supercritical, possibly time-inhomogeneous, binary branching processes, and in their boundary, which is the set of particles “coexisting at infinity”. We prove that any such tree can be mapped to a random, compact ultrametric tree called the coalescent point process, endowed with a “uniform” measure on its boundary which is the limit as $t\to\infty$ of the properly rescaled counting measure of the population at time $t$.

We prove that the clonal (i.e., carrying the same allele as the root) part of the boundary is a regenerative set that we characterize. We then study the allelic partition of the boundary through the measures of its blocks. We also study the dynamics of the clonal subtree, which is a Markovian increasing tree process as mutations are removed.

#### Article information

Source
Ann. Appl. Probab., Volume 28, Number 4 (2018), 2141-2187.

Dates
Revised: September 2017
First available in Project Euclid: 9 August 2018

https://projecteuclid.org/euclid.aoap/1533780270

Digital Object Identifier
doi:10.1214/17-AAP1353

Mathematical Reviews number (MathSciNet)
MR3843826

Zentralblatt MATH identifier
06974748

#### Citation

Duchamps, Jean-Jil; Lambert, Amaury. Mutations on a random binary tree with measured boundary. Ann. Appl. Probab. 28 (2018), no. 4, 2141--2187. doi:10.1214/17-AAP1353. https://projecteuclid.org/euclid.aoap/1533780270

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