How little is too little?: The adaptive value of floral integration

For more than a century the idea that natural selection favors high levels of floral integration has prevailed as a paradigm among floral biologists. However, there is very little empirical evidence of the adaptive value of floral integration. In this addendum we highlight an important result derived from an empirical study complemented with a literature review and mathematical simulations. Results indicated that intrafloral integration but not floral integration was selected among four species of Rosaceae. The literature review coupled with null models revealed that flowering plants have on average lower than expected levels of floral integration. Mathematical simulations further demonstrated that observed levels of floral integration might result from selection favoring increased intrafloral integration. Altogether, these findings suggest that in most flowering plants, floral integration has a low adaptive value and could be a by-product of selection favoring intrafloral integration.