Geographical Ecology of Dry Forest Tree Communities in the West Indies

Aim Seasonally dry tropical forest (SDTF) of the Caribbean Islands
(primarily West Indies) is floristically distinct from Neotropical SDTF in
Central and South America. We evaluate whether tree species composition
was associated with climatic gradients or geographical distance. Turnover
(dissimilarity) in species composition of different islands or among more
distant sites would suggest communities structured by speciation and
dispersal limitations. A nested pattern would be consistent with a steep
resource gradient. Correlation of species composition with climatic
variation would suggest communities structured by broad-scale
environmental filtering Location The West Indies (The Bahamas, Cuba,
Hispaniola, Jamaica, Puerto Rico, U.S. Virgin Islands, Guadeloupe,
Martinique, St. Lucia), Providencia (Colombia), south Florida (USA), and
Florida Keys (USA) Taxon Seed plants -- woody taxa (primarily trees)
Methods We compiled 572 plots from 23 surveys conducted between 1969-2016.
Hierarchical clustering of species in plots, and indicator species
analysis for the resulting groups of sites, identified geographical
patterns of turnover in species composition. Non-parametric analysis of
variance, applied to principal components of bioclimatic variables,
determined the degree of covariation of climate with location. Nestedness
versus turnover in species composition was evaluated using beta diversity
partitioning. Generalized dissimilarity modeling partitioned the effect of
climate versus geographical distance on species composition. Results
Despite a set of commonly occurring species, SDTF tree community
composition was distinct among islands and was characterized by spatial
turnover on climatic gradients that covaried with geographical gradients.
Greater Antillean islands were characterized by endemic indicator species.
Northern subtropical areas supported distinct, rather than nested, SDTF
communities in spite of low levels of endemism. Main conclusions SDTF
species composition was correlated with climatic variation. SDTF on large
Greater Antillean islands (Hispaniola, Jamaica and Cuba) was characterized
by endemic species, consistent with their geological history and the
biogeography of plant lineages. These results suggest that both
environmental filtering and speciation shape Caribbean SDTF tree
communities.