Evolution of leaflet shape in endemic Oxalis sect. Alpinae: an integrative approach using phylogeny and geometric morphometrics

MORELO, SANTIAGO; SASSONE, AGOSTINA B.; LOPEZ, ALICIA

Forth Worth, Texas

Congreso; Botany Conference 2017; 2017

Oxalis secc. Alpinae includes 17 speciesdistributed along the Andes. This sectionconstitutes a monophyletic group according tomolecular data. In the present work, themorphological variation of leaflets assigned to 12species of Oxalis is analyzed. Here we present anintegrative approach to elucidate the evolution ofleaftet shape in species of Oxalis, with thefollowing aims: 1) to analyze the morphologicalvariation; 2) to determine if morphological traitsof the leaflet can be used as diagnosticcharacters; 3) to further test the monophyly ofthe section; and 4) to assess the genetic andenvironmental processes involved in the evolutionof the leaflet of species of Oxalis. Leaflets werescanned and 262 contours were obtained. A total of312 outline coordinates were extracted from thebinary images and two landmarks were used to alignsamples. Elliptic Fourier Analysis (EFA) wasperformed on these outlines. Further methods werecarried on R using Momocs package, and we chose anumber of eight harmonics. A principal componentanalysis (PCA) was used to summarize theinformation. In order to study the phylogeneticrelationships in the section, Bayesian inferencewas performed from ITS sequences. EFA allowed usto characterize the shape of analyzed leaflets andto distinguish 3 groups of species from theirmorphological similarity. PCA analysis revealedmore than 99% of total variation is absorbed bythe first 6 PCs. More than 90% of the leafletsshape variance, represented by PC1 and PC2, isinfluenced by width and the incision. PCA showsthat species are loosely grouped but there is acontinuous of leaflet shape variation. Negativevalues of PC1 and PC2 represent typical heartshapes of Oxalis leaflets like those found in O.micrantha. Positive values of PC2 distinguishleaflets with shallow or null incision, likeleaflets of O. holosericea and O. hypsophylla.Phylogenetic branches in morphospace did not tendto radiate. Instead, they crossed one anotherrepeatedly, and distantly related terminals wereoften found in close proximity in morphospace, andsister clades are often found in opposite regions.Geometric morphometric data corroborated thesubjective impression that there is an overlap inleaflet shape among species of the sectionAlpinae. Leaflets shape does not always reflectphylogenetic relationships. These resultscontribute to the understanding of the patterns ofmorphological variation of Oxalis secc. Alpinae.