The adaptive value of phenotypic floral integration

MARIANO ORDANO; JUAN FORNONI; KARINA BOEGE; CÉSAR A. DOMÍNGUEZ

NEW PHYTOLOGIST

Blackwell Publishing Ltd.

Lugar: Oxford, UK; Año: 2008 vol. 179 p. 1183 - 1192

0028-646X

• Floral integration has been deemed an adaptation to increase the benefits of animalpollination, yet no attempts have been made to estimate its adaptive value undernatural conditions.• Here, the variation in the magnitude and pattern of phenotypic floral integrationand the variance–covariance structure of floral traits in four species of Rosaceae wereexamined. The intensity of natural selection acting on floral phenotypic integrationwas also estimated and the available evidence regarding the magnitude of floralintegration reviewed.• The species studied had similar degrees of floral integration, although significantdifferences were observed in their variance–covariance structure. Selection acted onsubsets of floral traits (i.e. selection on intrafloral integration) rather than on theintegration of the whole flower. Average integration was 20% and similar to theestimated mean value of flowering plants.• The review indicated that flowering plants present lower integration than expectedby chance. Numerical simulations suggest that this pattern may result from selectionfavouring intrafloral integration. Phenotypic integration at the flower level seems tohave a low adaptive value among the species surveyed. Moreover, it is proposed thatpollinator-mediated selection promotes the evolution of intrafloral integration.