A new Dominican amber fossil of the derived fern genus Pleopeltis confirms generic stasis in the epiphytic fern diversity of the West Indies

Abstract

One of the grand objectives in the integration of fossils and phylogenetics is to obtain support for macroecological and macroevolutionary hypotheses. Here, we provide new evidence from Dominican amber fossils, which supports a likely stasis in the generic composition of epiphytic plant communities in the West Indies for at least 16 million years. The proposed hypothesis is based on the discovery of the first fossil of the Neotropical fern genus Pleopeltis. The relationships of this specimen to extant genera are studied using a dated phylogenetic framework to reconstruct the evolution of the characters preserved in the fossil, as well as by exploring the phylomorphospace of Pleopeltis. The fossil corroborates divergence time estimates obtained independently and also suggests the conservation of the generic composition of epiphytic communities. We discovered evidence for conserved morphotypes in the genus Pleopeltis occurring from the mid-Miocene to the present. The innovative use of phylomorphospace reconstruction provided crucial information about the affinities of the fossil. Rather than relying on reconstructing the evolution of single characters, this analysis integrates the evolution of all informative characters observed to evaluate relationships of the fossilized morphotype to extant morphotypes.