Postglacial expansion of Rhizophora Mangle l. In the Caribbean Sea and Florida

The Last Glacial Maximum (LGM) was a period of massive range contraction for
numerous taxa, including the water-dispersed mangrove species, Rhizophora mangle L.
Following the LGM, R. mangle expanded poleward via propagule transport by ocean
currents. In this study, we use microsatellite loci to characterize the genetic structure of
nine R. mangle populations and compare potential expansion pathways that resulted in
the colonization of the Florida peninsula and Caribbean islands. Results show
comparatively greater genetic connectivity between the Caribbean mainland and Florida,
a similar pattern between West Africa and Caribbean islands, and substantial admixture
on the island of San Salvador, the Bahamas. We conclude that Florida and Caribbean
island R. mangle populations were likely recolonized via different expansion pathways.
Estimates of recent migration rates are low and populations are structured into three
regions (Caribbean mainland, Caribbean islands, Florida). These findings provide insight
for future management and conservation initiatives.