A PHYLOGENETIC ANALYSIS OF THE SOUTHERN PINES (PINUS SUBSECT AUSTRALES LOUDON) - BIOGEOGRAPHICAL AND ECOLOGICAL IMPLICATIONS

A parsimony analysis on morphological characters was performed to esti mate the phylogenetic relationships of the taxa of Pinus subsect. Aust rales. The Adams consensus tree placed the Caribbean species as a mono phyletic clade with P. rigida-P. serotina as its sister taxon. Based o n this phylogeny, area cladograms were constructed and compared to geo logic cladograms constructed from plate-tectonic evidence. This compar ison and an ancestral area analysis indicate that colonization of the tropics most likely occurred from Florida to Hispaniola, rather than b y the circumferential-Gulf route. Subsequent dispersal events to Centr al America, Cuba, and the Bahamas are proposed to explain the geograph ic distribution of P. caribaea. Ecological comparisons within subsect. Australes found that sister species are not syntopic and that syntopi c species are not sister species. Although some North American sister species are ecologically quite different, there is low ecological dive rsity among the Caribbean species.