Incorporate null model from Nunes and Pearson 2016?

[lxsllvn]

What do you think about adding this null model for phylogenetic niche divergence?

See: http://onlinelibrary.wiley.com/doi/10.1111/jbi.12910/full

[danlwarren]

It seems fairly do-able, but it would take a bit of work. Worth looking into at the very least.