Data from: Species selection maintains self-incompatibility

Identifying traits that affect rates of speciation and extinction and
hence explain differences in species diversity among clades is a major
goal of evolutionary biology. Detecting such traits is especially
difficult when they undergo frequent transitions between states.
Self-incompatibility, the ability of hermaphrodites to enforce
outcrossing, is frequently lost in flowering plants, enabling
self-fertilization. We show, however, that in the nightshade plant family
(Solanaceae), species with functional self-incompatibility diversify at a
significantly higher rate than those without it. Apparent short-term
advantages of potentially self-fertilizing individuals are therefore
offset by strong species selection, which favors obligate outcrossing.