Geographic variation in floral traits of the tree tobacco in relation to its hummingbirds pollinator fauna

NATTERO JULIETA; COCUCCI ANDREA

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

Blackwell

Año: 2006

0024-4066

 Nicotiana glauca, a hummingbird pollinated plant, exhibits geographic variation in several floral traits. We examined whether geographic differentiation occurred for different flower characters and if this differentiation could be explained, at least in part, by the existence or abundance of different hummingbird species in the respective pollinator assemblages. The comparison between five populations showed significant variation in six floral traits and two female fitness measures. The traits which better discriminated between populations were corolla length and corolla width. There were metric correlations between corolla length and style length in all populations studied, and in four of the five populations both corolla length and width were also correlated. Among plants in each population seed weight was correlated positively and significantly with style exertion suggesting that fruit quality is dependent on the degree of cross pollination. Assemblages of hummingbirds differed between populations in species composition, visitation frequencies and bill length. Linear regression involving bill length of the more frequent hummingbird pollinators and corolla length yielded positive and significant relationships. Thus, there appears to be an adjustment between pollinators and flowers traits that have high incidence in the among population variation.