Uncoupled Geographical Variation between Leaves and Flowers in a South-Andean Proteaceae

CHALCOFF VANINA RUTH; EZCURRA CECILIA; AIZEN MARCELO ADRIÁN

ANNALS OF BOTANY

Oxford University Press

Lugar: Oxford; Año: 2008 vol. 102 p. 79 - 91

0305-7364

Background and aims Geographic variation in foliar and floral traits and their degree of coupling can provide relevant information on the relative importance of abiotic, biotic and even neutral factors acting at geographical scales as generators of evolutionary novelty. We studied geographic variation in leaves and flowers of Embothrium coccineum, a species that grows along abrupt environmental gradients and exhibits contrasting pollinator assemblages in the southern Andes.Methods We considered five foliar and eight floral morphological characters from 32 populations, and analyzed their patterns of variation and covariation within and among populations, and their relation to environmental variables using both univariate and multivariate methods. We compared the relationship between foliar and floral morphological variation and geographic distance between populations with Mantel permutation tests.Key results Leaf and flower traits were clearly uncoupled within populations and weakly associated among populations. Whereas geographic variation in foliar traits was mostly related to differences in precipitation associated with geographic longitude, variation in floral traits was not.Conclusions These patterns suggest that leaves and flowers, responded to different evolutionary forces, environmental (i.e. rainfall) in the case of leaves, and biotic (i.e. pollinators) or genetic drift in the case of flowers. This study supports the view that character divergence at a geographic scale can be moulded by different factors acting in an independent fashion.