Pollinators drive floral evolution in an Atlantic Forest genus.

Area of Science:

• Ecology and Evolutionary Biology
• Plant-Pollinator Interactions
• Speciation

Background:

• Pollinators are key drivers of plant diversification across evolutionary scales.
• The genus Vriesea, found in the Brazilian Atlantic Forest, is pollinated by both hummingbirds and bats.
• Understanding the interplay between floral traits, pollinators, and genetic structure is crucial for evolutionary studies.

Purpose of the Study:

• To determine if floral traits in Vriesea predict specific pollinator functional groups, confirming pollination syndromes.
• To investigate whether genetic structure in Vriesea is influenced by geographical factors or ecological factors (pollination syndromes).
• To explore the role of pollinators in driving ecological isolation and speciation within Vriesea.

Main Methods:

• Analysis of 11 floral traits across 58 Vriesea species.
• Literature survey of Vriesea pollination biology.
• Phylogenetic analyses using chloroplast and nuclear molecular markers to infer haplotype genealogy.

Main Results:

• Floral traits accurately predicted functional groups of pollinators, confirming distinct pollination syndromes in Vriesea.
• Genetic groupings corresponded with pollination syndromes, indicating ecological drivers of genetic structure.
• Intermediate species with mixed floral types were identified, sharing haplotypes and exhibiting morphological differences.

Conclusions:

• Pollinator-driven ecological isolation plays a significant role in shaping Vriesea clades.
• Incipient speciation and incomplete lineage sorting contribute to low genetic divergence, obscuring clear species boundaries.
• The study reveals a morphological-genetic continuum indicative of ongoing pollinator-driven speciation in a biodiversity hotspot.