Neogene Diversification

During the Oligocene, the Caribbean mangroves were dominated by Rhizophora alone, as the other mangrove-forming trees (Avicennia, Laguncularia) and most mangroves associates were still absent. The diversification of Caribbean mangroves occurred during the Neogene and was complete in the Quaternary, in a so-called Neogene–Quaternary diversification trend (NQDT). This trend was marked by a rise of 25 genera compared to the 7 representatives from the Paleogene. The Miocene saw the emergence of only two genera, with the most significant increases occurring during the transition from Pliocene to Quaternary and in the contemporary living record. Half of the true-mangrove genera (Rhizophora, Pelliciera, Acrostichum) were already in existence before the Neogene, while the others gradually appeared in the Oligo-Miocene (Crenea), Early–Middle Miocene (Avicennia), and Mio-Pliocene (Laguncularia). None of the current associate mangrove genera were present during the Paleogene; all of them arose in the Miocene (23 genera) or during the Oligo-Miocene transition (3 genera), playing a major role in the NQDT in terms of sheer numbers. There have been no documented regional extinctions at the generic level in Caribbean mangroves since the Miocene. These findings call for additional in-depth quantitative studies to explore potential causal relationships with climatic, eustatic, and paleogeographical changes.