Latitudinal gradients in biotic interactions have been suggested as causes of global patterns of biodiversity and phenotypic variation. Plant biologists have long speculated that outcrossing mating systems are more common at low than high latitudes owing to a greater predictability of plant–pollinator interactions in the tropics; however, these ideas have not previously been tested. Here, we present the first global biogeographic analysis of plant mating systems based on 624 published studies from 492 taxa. We found a weak decline in outcrossing rate towards higher latitudes and among some biomes, but no biogeographic patterns in the frequency of self-incompatibility. Incorporating life history and growth form into biogeographic analyses reduced or eliminated the importance of latitude and biome in predicting outcrossing or self-incompatibility. Our results suggest that biogeographic patterns in mating system are more likely a reflection of the frequency of life forms across latitudes rather than the strength of plant–pollinator interactions.
Bibliographical noteFunding Information:
This project began as part of a working group, ‘Paradox of mixed mating systems in flowering plants’ at the National Evolutionary Synthesis Center (NESCent), which was funded by the National Science Foundation. We are grateful to other members of the working group, E. Porcher and J. Kelly for their comments and contributions.
© 2017 John Wiley & Sons Ltd/CNRS
- Biotic interactions
- breeding system
- floral evolution
- latitudinal gradient
- life history
- plant–pollinator interaction
- sexual system