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

NATTERO J.; COCUCCI A. A.

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

Año: 2007 vol. 90 p. 657 - 667

0024-4066

AbstractNicotiana glauca, a hummingbird pollinated plant, exhibits geographic variationin several floral traits. We examined whether geographic differentiation occurred fordifferent flower characters and if this differentiation could be explained, at least in part,by the existence or abundance of different hummingbird species in the respectivepollinator assemblages.The comparison between five populations showed significant variation in sixfloral traits and two female fitness measures. The traits which better discriminatedbetween populations were corolla length and corolla width. There were metriccorrelations between corolla length and style length in all populations studied, and infour of the five populations both corolla length and width were also correlated. Amongplants in each population seed weight was correlated positively and significantly withstyle exertion suggesting that fruit quality is dependent on the degree of crosspollination. Assemblages of hummingbirds differed between populations in speciescomposition, visitation frequencies and bill length.Linear regression involving bill length of the more frequent hummingbirdpollinators and corolla length yielded positive and significant relationships. Thus, thereappears to be an adjustment between pollinators and flowers traits that have highincidence in the among population variation.KEY WORDS: floral traits- hummingbird - Nicotiana glauca - pollination -geographic variation.AbstractNicotiana glauca, a hummingbird pollinated plant, exhibits geographic variationin several floral traits. We examined whether geographic differentiation occurred fordifferent flower characters and if this differentiation could be explained, at least in part,by the existence or abundance of different hummingbird species in the respectivepollinator assemblages.The comparison between five populations showed significant variation in sixfloral traits and two female fitness measures. The traits which better discriminatedbetween populations were corolla length and corolla width. There were metriccorrelations between corolla length and style length in all populations studied, and infour of the five populations both corolla length and width were also correlated. Amongplants in each population seed weight was correlated positively and significantly withstyle exertion suggesting that fruit quality is dependent on the degree of crosspollination. Assemblages of hummingbirds differed between populations in speciescomposition, visitation frequencies and bill length.Linear regression involving bill length of the more frequent hummingbirdpollinators and corolla length yielded positive and significant relationships. Thus, thereappears to be an adjustment between pollinators and flowers traits that have highincidence in the among population variation.KEY WORDS: floral traits- hummingbird - Nicotiana glauca - pollination -geographic variation.