Christianini et al. 2013 (Article) Encholirium, Rocky Outcrops

Divergence on floral traits and vertebrate pollinators of two endemic Encholirium bromeliads

Author(s):—A.V. Christianini, R. C. Forzza & S. Buzato

Corresponding email:—sbuzato@usp.br

Publication:—Plant Biology 15(2): 360-368. (2013) — DOI

Abstract:—Shifts in pollen vectors favour diversification of floral traits, and differences in pol- lination strategies between congeneric sympatric species can contribute to reproduc- tive isolation. Divergence in flowering phenology and selfing could also reduce interspecific crossing between self-compatible species. We investigated floral traits and visitation rates of pollinators of two sympatric Encholirium species on rocky outcrops to evaluate whether prior knowledge of floral characters could indicate actual pollinators. Data on flowering phenology, visitation rates and breeding sys- tem were used to evaluate reproductive isolation. Flowering phenology overlapped between species, but there were differences in floral characters, nectar volume and concentration. Several hummingbird species visited flowers of both Encholirium spp., but the endemic bat Lonchophylla bokermanni and an unidentified sphingid only visited E. vogelii. Pollination treatments demonstrated that E. heloisae and E. vogelii were partially self-compatible, with weak pollen limitation to seed set. Herbivores feeding on inflorescences decreased reproductive output of both species, but for E. vogelii the damage was higher. Our results indicate that actual pollinators can be known beforehand through floral traits, in agreement with pollination syn- dromes stating that a set of floral traits can be associated with the attraction of spe- cific groups of pollinators. Divergence on floral traits and pollinator assemblage indicate that shifts in pollination strategies contribute to reproductive isolation between these Encholirium species, not divergence on flowering phenology or sel- fing. We suggest that hummingbird pollination might be the ancestral condition in Encholirium and that evolution of bat pollination made a substantial contribution to the diversification of this clade.

Keywords:—Breeding system; Bromeliaceae; herbivore; hummingbird; nectar-feeding bat; plant– animal interactions; pollination syndromes.