Morphological Evolution in the Mulberry Family (Moraceae)

Abstract

The mulberry family Moraceae comprises 37 genera and approximately 1,100 species distributed throughout tropical and temperate regions worldwide. Moraceae exhibit a complex array of inflorescence architectures, breeding systems, and pollination syndromes, which forms the basis of traditional taxonomic classification. However, morphologically based classification conflicts with evolutionary relationships proposed by molecular phylogenetics. In this study we assembled a morphological character matrix for analysis separately and in combination with existing molecular data. We evaluated 81 vegetative, reproductive, and wood anatomical characters for 94 species representing nearly all Moraceae genera. Using parsimony and Bayesian methods, these characters were evaluated with respect to ndhF chloroplast and 26S nuclear DNA sequences. Topological comparisons tested whether opposing classification schemes are more or less supported by the data. Results did not support any classification of Moraceae based on morphology. We present a revised tribal classification and describe a new tribe, Maclureae, revise the membership of tribe Castilleae and describe two subtribes, Castillineae and Antiaropsineae, and reinstate the genera Malaisia (including Malaisia scandens) and Sloetia (including Sloetia elongata). Lastly we discuss the evolution of inflorescence architecture in relation to other floral features.