Résumé
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.