Research Fragments

A scientific blog by Guilhem Doulcier.

19 Oct 2018

Coalescent Point Processes


Coalescent Point Processes are random ultrametric trees yielding interesting results for evolutionary biology.

More specifically, a Coalescent Point Process with stem age T and scale function F is a sequence of iid. random variables (H_i)_{i\geq 1} \sim H, such that F(t) = \frac{1}{\mathbb P(H>t)} killed at the first value H_i>T.

Getting a CPP from a splitting tree

To me the most magic thing about CPP is that you can actually find a distribution for H so that the CPP accurately represent the descent of an individual following a biologically relevant population dynamics model. (Cf proposition 5 in Lambert & Stadler, 2013)

As an example, consider the linear birth-death process with constant birth rate b and constant death rate d.

CPP simulated with the inverse of cumulative probability function method.

References

Source: main.js Software used: d3js.