  For a family of models of evolving population under selection, which can be
described by noisy traveling wave equations, the coalescence times along the
genealogical tree scale like $\log^\alpha N$, where $N$ is the size of the
population, in contrast with neutral models for which they scale like $N$. An
argument relating this time scale to the diffusion constant of the noisy
traveling wave leads to a prediction for $\alpha$ which agrees with our
simulations. An exactly soluble case gives trees with statistics identical to
those predicted for mean-field spin glasses in Parisi's theory.
