Moments of the frequency spectrum of a splitting tree with neutral Poissonian mutations

Nicolas Champagnat; Benoît Henry

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arXiv · 1509.06500

Moments of the frequency spectrum of a splitting tree with neutral Poissonian mutations

Nicolas Champagnat·Benoît Henry

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Abstract

We consider a branching population where individuals live and reproduce independently. Their lifetimes are i.i.d. and they give birth at a constant rate b. The genealogical tree spanned by this process is called a splitting tree, and the population counting process is a homogeneous, binary Crump-Mode-Jagers process. We suppose that mutations affect individuals independently at a constant rate $\θ$ during their lifetimes, under the infinite-alleles assumption: each new mutation gives a new type, called allele, to his carrier. We study the allele frequency spectrum which is the numbers A(k, t) of types represented by k alive individuals in the population at time t. Thanks to a new construction of the coalescent point process describing the genealogy of individuals in the splitting tree, we are able to compute recursively all joint factorial moments of (A(k, t)) k$\ge$1. These moments allow us to give an elementary proof of the almost sure convergence of the frequency spectrum in a supercritical splitting tree.

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BibTeX RIS

Nicolas Champagnat, Benoît Henry. 2016-09-02. Moments of the frequency spectrum of a splitting tree with neutral Poissonian mutations. https://arxiv.org/abs/1509.06500

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