Wiens et al. (2006) examined the rate of diversification in
relation to latitude in hylid frogs. They found that the rate of
diversification did not differ by latitude, but there were more
diverse groups in lower latitudes than in higher latitudes.
Furthermore, they conducted a regression using phylogenetic
contrasts, which corrects for evoutionary relationships while
examining things like habitat-diversity corelations. How can
we interpret their results indicating no latitudinal difference in
diversity rates and why is it important that they used a
phylogenetic contrast rather than a standard correlation?