Molecular phylogenetics and historical biogeography of five Greater Antillean plant groups: Goetzeoideae, Reynosia, Wallenia, Calyptronoma, and Roystonea.

摘要

The flora of the Caribbean Islands is highly diverse, with much of its endemicity being concentrated in the Greater Antilles. This study provides an introduction on current knowledge on Caribbean phytogeography and discuss considerations for future studies. We conducted phylogenetic analyses in five Antillean-centered plant groups: Goetzeoideae, Reynosia, Wallenia, Roystonea, Calyptronoma. One of the objectives was to elucidate species relationships of each plant group. Two other objectives were to assess character evolution and evaluate their historical biogeography. Phylogenetic reconstruction based on DNA sequences of the nuclear rDNA ITS region, and the chloroplast trnL/F region, and ndhF and rbcL genes confirms the monophyly of the Antillean genera Coeloneurum, Espadaea, Henoonia, and Goetzea. These genera, together with the South American Duckeodendron and Metternichia , form one of the most basal lineages of the Solanaceae. The molecular phylogeny is in agreement with pollen morphology. The results indicate a trend of evolution from wet-mesic towards xeric environments, and from nocturnal insect pollination towards diurnal insect and bird pollination. The molecular phylogenies of Reynosia and Wallenia are not in full agreement with the subgeneric classifications of the traditional taxonomy. In Reynosia, apetaly is a synapomorphy that unifies several Cuban species, but the presence of an apicular spine has evolved independently in more than one lineage. The results confirm the previous hypothesis of evolution towards xeric habitats. In Wallenia, species with pendulous inflorescences are derived from those with erect, cymose inflorescences. Species from high elevation and from xeric habitat are derived from species from mesic, mid elevations. Based on a tree reconciliation analysis, lineage diversification as the result of a vicariant scenario is only supported in the Goetzeoideae. However, simple dispersal scenarios are also plausible. The low sequence divergence in many species lineages, as well as the high incongruence between the species tree and the tectonic-vicariant models of island origination indicate that some endemic plant groups might be younger than what has been inferred before. The results indicate that dispersal might be playing a major role in shaping distribution of Antillean endemic groups. Our results found very little sequence divergence in Calyptronoma and Roystonea.