Flower morphology evolution in Jaborosa (Solanaceae): shape and size variation associated with contrasting pollination modes.

(1) Flower morphology has been considered an important factor in species diversification because it may influence the efficiency of pollination in different ways (e.g. attraction and mechanical fit with different groups of pollinators). (2) In the present study, we quantified the variation in flower morphology (i.e. shape and size) of the diverse South American genus Jaborosa Juss. (Solanaceae) in relation to contrasting pollination modes: rewarding pollination either by moths or by generalist small insects vs. brood-site deceptive pollination by saprophilous flies. We examined the variation of flower morphology in frontal (pollinator attraction) and sagittal (functional fit with pollinators) views in twelve Jaborosa species using geometric morphometric methods and comparative approaches to infer whether flower shape evolution, not attributable to flower allometry or phylogenetic relationship, is associated with shifts in pollination modes. (3) We found remarkable variation in flower morphology among both Jaborosa species and pollination modes, largely in sagittal view. Evolutionary trends in shape of fly-pollinated flowers were mainly attributable to changes in developmental trajectories. Variation in flower architecture facilitated differential pollen placement: on the proboscis of moths, and either on the back or ventral region of saprophilous flies, promoting the diversification of the genus. (4) Diversification of shape independently of size in most of the studied Jaborosa species would indicate adaptation to contrasting pollination modes.