The Pelliciera Taxon Cycle: A Time-Continuum Integrative Synthesis

The taxon cycle concept introduces the idea of a species undergoing repeated expansions and contractions in its range over time to sustain its core distribution indefinitely; otherwise, it faces extinction. Taxon cycles are commonly associated with tropical island faunas, examples from continental regions are scarce, and there is a lack of similar case studies for plants. Most taxon cycles have been recognized through phylogeographical studies, with limited empirical evidence from fossils. The fossil record of an emblematic Caribbean mangrove element, Pelliciera, provides empirical fossil evidence supporting the recurring expansion and contraction trends between its original core area and the whole Neotropics. Indeed, the observed recurrent patterns are consistent with the taxon cycle concept from biogeographical, chronological, and ecological perspectives. In a taxon cycle ontext, the Pelliciera–Rhizophora tradeoff during the EOT may be viewed as more than a facilitation process, as Pelliciera not only survived but have also had new unexpected possibilities for range expansion and speciation. The recurrent patterns of expansion and contraction observed in Pelliciera hold significant promise as the first taxon cycles that have been empirically recorded, and they appear to be the sole documented instance of taxon cycles in plants thus far. Whether the Pelliciera taxon cycle could represent a trend toward extinction may be relevant for its conservation.