Are nectar-sugar composition and corolla-tube length related to the diversity of insects that visit Asteraceae flowers?

TORRES, C.; GALETTO, L.

PLANT BIOLOGY

Georg Thieme Verlag Stuttgart

Lugar: New York; Año: 2002 vol. 4 p. 360 - 366

1435-8603

In this work. we analysed interspecific variation in nectar sugar composition. corolIa tube length. and the diversitythis work. we analysed interspecific variation in nectar sugar composition. corolIa tube length. and the diversitytube length. and the diversity of floral visitors of 35 Asteraceae species. The potential correlations between these variables could arise either as a result offloral visitors of 35 Asteraceae species. The potential correlations between these variables could arise either as a result ofthese variables could arise either as a result of selection to improve pollinator attractiveness or simply as a consequence of phylogenetk constraints. Samples of nectar and flowers, and data on floral visitors, were obtained from living plants in natural populations from Argentina. Asteraceaeto improve pollinator attractiveness or simply as a consequence of phylogenetk constraints. Samples of nectar and flowers, and data on floral visitors, were obtained from living plants in natural populations from Argentina. Asteraceae species showed a large variability in coralla tube length. Nectarshowed a large variability in coralla tube length. Nectar of most species presented a larger proportion of hexoses than sucrose. All species were visited by numerous insects belongingmost species presented a larger proportion of hexoses than sucrose. All species were visited by numerous insects belongingspecies were visited by numerous insects belonging to 12 different orders. Results showed that floral traits are not significantly correlated with the diversity of floral visitors.12 different orders. Results showed that floral traits are not significantly correlated with the diversity of floral visitors. These characters reern to be linked to the phylogeny of the species.reern to be linked to the phylogeny of the species. Early brancliing species (species phylogenetically close tobrancliing species (species phylogenetically close to the root of the Asteraceae tree) tend to have longer corollas. higher sucrose proportions and lesser diversity of floral visitors than late branching species. Considering that longer corolla tubes and higher nectar sucrose percentages may indicate some specialization in the porlination system, we suggest that there is an evolutionary tendency toward generalist pollinationof the Asteraceae tree) tend to have longer corollas. higher sucrose proportions and lesser diversity of floral visitors than late branching species. Considering that longer corolla tubes and higher nectar sucrose percentages may indicate some specialization in the porlination system, we suggest that there is an evolutionary tendency toward generalist pollinationsucrose percentages may indicate some specialization in the porlination system, we suggest that there is an evolutionary tendency toward generalist pollinationsuggest that there is an evolutionary tendency toward generalist pollinationan evolutionary tendency toward generalist pollination systems within the family.within the family.