Phylogenetic analysis of the genus Hampea (Malvales: Malvacea: Gossypieae)

Abstract

A PHYLOGENETIC ANALYSIS WAS CONDUCTED OF THE 21 KNOWN SPECIES OF THE GENUS HAMPEA (MALVALES: MALVACEAE: GOSSYPIEAE), A GENUS ENDEMIC TO MEXICO (SOUTH OF 22° N), CENTRAL AMERICA AND COLOMBIA. USING EXTERNAL MORPHOLOGICAL CHARACTERS, A SIGLE TREE OF A MINIMUM LENGTH OF 94 WAS CALCULATED WITH A CONSISTENCY AND RETATION INDEX OF 0.413 AND 0.645, RESPECTUVELY. RESULTS SUGGEST THAT THE GENUS FIRST DIVERSITIED IN THE REGION OF SOUTHERN MEXICO AND NORTHERN CENTRAL AMERICA AND THEN LATER DISPARED SOUTHWARD AND NORTHWARD. AN EARLY DIVERGENCE OF THE GENUS APPARENTLY OCCURRED BETWEEN ANCESTRAL POPULATIONS ON THE ATLANTIC VERSUS THE PACIFIC COASTAL PLAINS. RESULTS FURTHER SUGGEST THAT HAMPEA SPECIES NOW OCCURRING IN MONTANE HABITATS ARE DERIVED FROM LOWLAND ANCESTORS. ADDITIONALLY, SEVERAL CHARCTERS (MONOMORPHIC VERSUS DIMORPHIC FLOWERS, PRESENCE AND FORM OF EXTRAFLORAL NECTARIES, AND THE PRESENCE OF DOMATIA) WHICH ARE USEFUL IN DISTINGUISHING SPECIES PROVED TO BE RELATIVELY HOMOPLASTIC IN PHYLOGENETIC ANALYSIS. oBSERVATIONS INTHE FIELD INDICATED THAT THE HOMOPLASTICITY OF THESE CHARACTERS WAS POSSIBLY DUE TO THEIR ADAPTIVE VALUE UNDER DIFFERENT ECOLOGICAL CONDITIONS. FURTHER BIOGEOGRAPHIC CONCLUSIONS AND POSSIBLE FUTURE RESEARCH TOPICS CONCERNING THE EVOLUTION OF HAMPEA ARE DISCUSSED.