  In this paper I address the question - how large is a phylogenetic sample I
propose a definition of a phylogenetic effective sample size for Brownian
motion and Ornstein-Uhlenbeck processes - the regression effective sample size.
I discuss how mutual information can be used to define an effective sample size
in the non-normal process case and compare these two definitions to an already
present concept of effective sample size (the mean effective sample size).
Through a simulation study I find that the AICc is robust if one corrects for
the number of species or effective number of species. Lastly I discuss how the
concept of the phylogenetic effective sample size can be useful for
biodiversity quantification, identification of interesting clades and deciding
on the importance of phylogenetic correlations.
