Different Methodologies Result in Opposite Patterns of Diversification Rates in Flowering Plants Across Latitudes.

There are two major groups of methods estimating diversification rates: One group depends on well resolved phylogenies and the other is phylogeny-free. Previous studies on angiosperms (flowering plants) have used phylogeny-based methods to estimate diversification rates and concluded that diversification rates increase with increasing latitudes, a trend opposite to that of liverworts, mosses and ferns, for which diversification rates were estimated with the method-of-moments estimator, a nonphylogeny method. In this study, we use the method-of-moments estimator to estimate diversification rates of angiosperm species within genera worldwide. We find that diversification rates decrease with increasing latitudes. The result of our study is thus contrary to those of previous studies on angiosperms. We discuss the degree to which these differences are due to methodological limitations of using phylogeny-based approaches to estimate diversification rates of angiosperms. More data from poorly studied angiosperm groups are needed so that we can move toward developing well-resolved species-level phylogenies for angiosperms, which will allow a better assessment of the robustness of various diversification estimation methods.