Phylogeny and historical biogeography of the lastreopsid ferns (Dryopteridaceae)

Abstract

• Premise of the study: As currently circumscribed, Lastreopsis has about 45 species and occurs in Australia, southern Asia, Africa, Madagascar, and the neotropics. Previous molecular phylogenetic studies suggested that Lastreopsis is paraphyletic. Our study focuses on resolving relationships among the lastreopsid ferns (Lastreopsis, Megalastrum, and Rumohra), the evolution of morphological characters, and an understanding of the temporal and spatial patterns that have led to the current diversity and geographical distribution of its extant species.• Methods: Phylogenetic relationships were recovered under Bayesian, maximum likelihood, and maximum parsimony methods, using a data set of four plastid markers. Divergence time estimates were made using BEAST, and the biogeographic hypotheses were tested under the DEC model and the RASP/S-DIVA methods.• Key results: Lastreopsis was recovered as paraphyletic, and at least one of its clades should be recognized as a distinct genus, Parapolystichum. Coveniella poecilophlebia and Oenotrichia tripinnata were nested within Lastreopsis s.s., Megalastrum and Rumohra as sister to the Lastreopsis s.s., and the Lastreopsis amplissima clades. The initial diversification of the lastreopsids took place at about 56.55 Ma, from a neotropical ancestor.• Conclusions: Taxonomic recognition of Parapolystichum is warranted to preserve the monophyly of Lastreopsis. Diversification among the main clades of the lastreopsid ferns was influenced by climatic and geological changes in the southern hemisphere. The biogeographic history of the group is intimately related to the trans-Antarctic corridor between Australia and South America, with evidence for multiple lineage interchanges between Australia and South America during the Oligocene and the Eocene epochs.

A well-sampled phylogenetic analysis of the polystichoid ferns (Dryopteridaceae) suggests a complex biogeographical history involving both boreotropical migrations and recent transoceanic dispersals

“…Li et al (2004) used substitution rate to estimate divergence times and this method is known to generate large discrepancies in dating estimates and should therefore be interpreted with caution (Pulquério and Nichols, 2007;Rutschmann, 2006). Our Bayesian relaxed clock approach, using both secondary and fossil constraints, seems to provide more reliable results, similar to those found by other studies with comparable methods and calibration schemes (Labiak et al, 2014;McHenry and Barrington, 2014;Schuettpelz and Pryer, 2009;Sessa et al, 2012a).…”

“…These findings involve a careful re-examination of the importance of LDD versus vicariance events (Haufler, 2007;Wolf et al, 2001). For instance, the geographical distribution pattern of several fern taxa such as the lastreopsid (Lastreopsis Ching, Megalastrum Holttum, Rumhora Raddi; Dryopteridaceae) and scaly tree ferns (Cyatheaceae) have been interpreted as a combination of vicariance as a result of the break-up of Gondwana, and recent transoceanic LDD (Korall and Pryer, 2014;Labiak et al, 2014). …”

New records of Megalastrum in the northeastern Atlantic Forest

“…Megalastrum is a member of a clade informally recognized as the "lastreopsid ferns", which also includes Lastreopsis, Parapolystichum and Rumohra (Labiak et al 2014). In Brazil there are 18 recorded species, 13 of which are endemic.…”

Sobre la presencia de Megalastrum substrigosum (Dryopteridaceae) en Argentina

“…C. Chr., recientes estudios filogenéticos basados en ADN revelan que Rumohra Raddi es el género hermano de Megalastrum, y que estos últimos dos géneros están emparentados con Lastreopsis Ching (Schuettpelz & Pryer, 2007;Labiak et al 2014).…”