RATE OF GENE SEQUENCE EVOLUTION AND SPECIES DIVERSIFICATION IN FLOWERING PLANTS - A REEVALUATION

Barraclough and co-workers (in a paper published in 1996) observed tha t there was a significant positive correlation between the rate of evo lution of the rbcL chloroplast gene within families of flowering plant s and the number of species in those families. We tested three additio nal data sets of our own (based on both plastid and nuclear genes) and used methods designed specifically for the comparison of sister famil ies (based on random speciation and extinction). We show that, over al l sister groups, the correlation between the rate of gene evolution an d an increased diversity is not always present. Despite tending toward s a positive association, the observation of individual probabilities presents a U-shaped distribution of association (i.e. it can be either significantly positive or negative). We discuss the influence of both phylogenetic sampling and applied taxonomies on the results.