No association between plant mating system & geographic range overlap
Dena Grossenbacher , Ryan Briscoe Runquist , Emma Goldberg , Yaniv Brandvain
Both evolutionary theory and numerous case studies suggest that selfing taxa are more likely to co-occur with outcrossing relatives than are outcrossing taxa. Despite suggestions that this pattern may be general, the extent to which mating system influences range overlap in close relatives has not been tested formally across a diverse group of plant species pairs. We test for a difference in range overlap between species pairs where zero, one, or both species are selfers with data from 98 sister species pairs in 20 genera. We also use divergence time estimates from time-calibrated phylogenies to ask how range overlap changes with divergence time and whether this effect depends on mating system. We find no evidence that self-pollination influences range overlap of closely related species. While the extent of range overlap decreased modestly with the divergence time of sister species, this effect did not depend on mating system. The absence of a strong influence of mating system on range overlap suggests that of the many mechanisms potentially influencing the co-occurrence of close relatives, mating system plays a minor and/or inconsistent role.