PERRET, MATHIEU*, ALAIN CHAUTEMS, RODOLPHE SPICHIGER, AND VINCENT SAVOLAINEN. Conservatoire et Jardin botaniques, Geneva, CH 1292, Switzerland; Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, United Kingdom. - Floral diversification and speciation in Sinningieae inferred from
phylogenetic analysis of plastid and nuclear cpGS gene sequences.
The tribe Sinningieae (neotropical Gesneriaceae) comprises three
genera (Sinningia, Paliavana and Vanhouttea) with a
total of 75 species exhibiting bee, moth, hummingbird and bat
pollination syndromes. The phylogeny of all species was inferred using
five plasid non-coding DNA regions (atpB-rbcL, trnT-trnL, trnL-trnF,
trnS-trnG, rpl16) and the nuclear-encoded chloroplast glutamine
synthetase (ncpGS). Molecular cloning of ncpGS PCR products and
infraspecific samplings revealed sequence variation within one third
of the species. Allelic polymorphism of ncpGS and comparison between
trees obtained from ncpGS gene and plastid regions combined were used
to infer putative introgression events among Sinningieae. Based on a
species-level phylogeny, evolution of floral morphology and nectar
reward chemistry were reconstructed. Frequent parallelisms and
reversals in pollination syndromes were observed. Specific sugar
chemistries in nectar were found in species with bat and moth
syndromes, whereas no significant difference in nectar composition
were found in bee and hummingbird-pollinated species, thereby
facilitating multiple shifts between these latter syndromes.
Comparison of geographic area overlaps between sister species indicate
that allopatric speciation was most common, with subsequent phenotypic
changes and adaptations to pollinators.
Key words: floral evolution, Gesneriaceae, ncpGS, phylogeny, Sinningia, speciation