Erin Zimmerman1, Patrick S Herendeen2, Gwilym P Lewis3, Anne Bruneau1. 1. Institut de Recherche en Biologie Végétale and Département de Sciences Biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada. 2. Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, Illinois 60022 USA. 3. Comparative Plant and Fungal Biology Department, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, United Kingdom.
Abstract
PREMISE OF THE STUDY: The Dialioideae is an early diverging clade of caesalpinioid legumes containing approximately 85 species in 17 genera. Dialioideae floral morphology is highly variable and may provide clues to caesalpinioid evolution, but a well-resolved phylogeny is needed. Here, we have carried out a comprehensive morphological study of 78 Dialioideae and four outgroup species. METHODS: For all available Dialioideae DNA samples, the plastid rpS16 and trnL introns were sequenced. A combined phylogenetic analysis using the parsimony criterion was completed on a reduced taxon set for which both molecular and morphological data were available. Highly supported clades from the strict consensus tree of this analysis were then used to constrain the nodes of a second analysis on an expanded taxon set with missing molecular data for some taxa. KEY RESULTS: Several new, highly supported relationships have been discovered at the species and genus levels. The loss of the antepetalous stamen whorl was found to be a synapomorphy for most of the clade. CONCLUSIONS: A high degree of organ loss is common in the Dialioideae and often results in a bilaterally symmetrical flower. The absence of consistent morphological features in the Dialioideae, coupled with the small size of each florally diagnosed genus, suggests a lack of canalization in the floral evolution in early diverging legume lineages.
PREMISE OF THE STUDY: The Dialioideae is an early diverging clade of caesalpinioid legumes containing approximately 85 species in 17 genera. Dialioideae floral morphology is highly variable and may provide clues to caesalpinioid evolution, but a well-resolved phylogeny is needed. Here, we have carried out a comprehensive morphological study of 78 Dialioideae and four outgroup species. METHODS: For all available Dialioideae DNA samples, the plastid rpS16 and trnL introns were sequenced. A combined phylogenetic analysis using the parsimony criterion was completed on a reduced taxon set for which both molecular and morphological data were available. Highly supported clades from the strict consensus tree of this analysis were then used to constrain the nodes of a second analysis on an expanded taxon set with missing molecular data for some taxa. KEY RESULTS: Several new, highly supported relationships have been discovered at the species and genus levels. The loss of the antepetalous stamen whorl was found to be a synapomorphy for most of the clade. CONCLUSIONS: A high degree of organ loss is common in the Dialioideae and often results in a bilaterally symmetrical flower. The absence of consistent morphological features in the Dialioideae, coupled with the small size of each florally diagnosed genus, suggests a lack of canalization in the floral evolution in early diverging legume lineages.
Authors: Erik J M Koenen; Dario I Ojeda; Freek T Bakker; Jan J Wieringa; Catherine Kidner; Olivier J Hardy; R Toby Pennington; Patrick S Herendeen; Anne Bruneau; Colin E Hughes Journal: Syst Biol Date: 2021-04-15 Impact factor: 15.683