Abstract
Miconieae is the largest tribe in the Melastomataceae with over 1,850 species. The members of Miconieae display a wide range of morphological diversity, and seed morphology is no exception. Previous studies have found that seed morphological diversity is not congruent with traditional classifications, and suggest that it may reflect evolutionary relationships within Miconieae. Here we characterize seed morphology of 364 species of Miconieae. The morphological data set and a DNA sequence data matrix were analyzed under a parsimony and Bayesian framework. Seed characters were used to test taxonomic and clade hypotheses, to estimate morphological ancestral character states, and to assess phylogenetic signal. The phylogenetic analyses of morphological data retrieved a poorly-resolved, low-supported phylogeny; in contrast, a relatively strongly supported phylogeny was estimated using the molecular data. Hypothesis testing procedures could only reject the monophyly of Clidemia, Leandra, and Miconia. The results indicated that the seed morphological characters were homoplasious, but contained phylogenetic signal. The morphological seed types that were described in previous studies did not support any of the clades retrieved by the molecular phylogeny. In contrast with previous investigations, our study shows that although seed morphology is very variable, it does not provide information for supporting some genera or clades within Miconieae. However, it is suggested that seed characters in combination with other vegetative and reproductive traits may aid in the characterization of smaller clades. The presence of phylogenetic signal retrieved by homoplasious characters may indicate that diversification of seed characters could have an adaptive component. Further studies that increase taxon sampling, refine seed trait characterization, and evaluate the alleged relationships between environmental variables and seed diversification will contribute to a better understanding of seed morphology and evolution in this species-rich tribe.
Highlights
Seed morphology has long been considered an important source of character information for taxonomic purposes and has been proposed as a feature that reflects the evolutionary history of plants [1]
Seed sample preparation, scanning electron microscopy (SEM) image acquisition, and seed length measurements were done at the California Academy of Sciences (CAS) and the New York Botanical Garden (NY), following the procedures described by Ocampo and Almeda [31]
We evaluated in a phylogenetic context the taxonomic, systematic, and evolutionary implications of seed morphology diversity of ca. 20% of the species of Miconieae
Summary
Seed morphology has long been considered an important source of character information for taxonomic purposes and has been proposed as a feature that reflects the evolutionary history of plants [1]. More recent investigations have found that seed morphological traits do not always correspond to proposed classifications [19,20,21,22]. These studies suggested that the delimitation of some tribes and genera should be reconsidered using seed morphology based on the assumption that seed morphology yields information about the evolutionary history of the groups under study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
