Adaptive evolution of reproductive and vegetative traits driven by breeding systems

VERDÚ, M.; GLEISER, G.

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Año: 2006 vol. 169 p. 409 - 417

0028-646X

The evolution of inflorescence size, a key trait in reproductive success, was studiedin the genus Acer under a perspective of adaptive evolution. Breeding systems,hypothesized to indicate different levels of mating competition, were consideredas the selective scenarios defining different optima of inflorescence size. Largerinflorescences, which increase male fitness by generating larger floral displays, werehypothesized to be selected under scenarios with higher competition with unisexuals.An identical approach was used to test if the same selective regimes could be drivingthe evolution of leaf size, a vegetative trait that was found to be correlated withinflorescence size.A Brownian motion model of inflorescence/leaf-size evolution (which cannotdistinguish between changes caused by pure drift processes and changes causedby natural selection in rapidly and randomly changing environments) was comparedwith several adaptive Ornstein?Uhlenbeck (OU) models, which can quantify theeffects of both stochasticity and natural selection.The best-fitting model for inflorescence/leaf-size evolution was an OU modelwith three optima that increased with the level of mating competition.Both traits evolved under the same selective regimes and in the same direction,confirming a pattern of correlated evolution. These results show that a selectiveregime hypothetically related to the evolution of a reproductive trait can also explainthe evolution of a vegetative trait.