Abstract

Evolution of higher plants on oceanic islands is now understood to be different in certain respects from that in plant groups of continental regions. This volume re-emphasizes the long-held view that island plants often undergo rapid speciation under directional selection through adaptive radiation. Such dramatic morphological change is usually not accompanied by changes in chromosome number (nor structural rearrangements) nor in genetic composition as evidenced by isozyme and RAPD loci. Geographic isolation, especially between islands, is fundamental as a stimulus for speciation. Change in island size and habitat spectra over geological time causes rapid ecological shifts and concomitant extinctions. Modern sources of data and methods of analysis have provided us with some of these newer perspectives and suggest continued research protocols involving: (1) basic floristic inventories using consistent species concepts; (2) preliminary evolutionary hypotheses; (3) geological data and history (especially of vulcanism); (4) explicit phylogenetic hypotheses; (5) estimates of character evolution, including co-evolution and adaptive complexes; (6) postulates of modes of speciation; (7) rigorous biogeographic analyses; and (8) communication of conservation priorities to appropriate officials and agencies.

This volume illustrates the breadth of plant island biological studies from the morphological to the molecular and from the phylogenetic to the biogeographic. The chapters contained herein reflect the dynamic nature of studies of oceanic islands, which in large measure parallel existing ideas and approaches now prevalent in modern plant systematics and evolutionary biology (e.g., Hoch & Stephenson, 1995).