Genetic and Morphological Diversity of Microsorum Link emend. Ching (Polypodiaceae) in Niue Confirms Three Indigenous Species
TL;DR
A taxonomic appraisal of Microsorum in Niue is presented using chloroplast and nuclear DNA sequence data obtained from 25 samples along with an assessment of morphological characters and the habitats occupied, indicating complex hybridisation involving M. grossum, M. papuanum, and M. scolopendria.
Abstract
We present a taxonomic appraisal of Microsorum in Niue using chloroplast ( rbcL , rps4 + rps 4‐ trn S, trnL + trn L‐ trn F) and nuclear ( gapCp ) DNA sequence data obtained from 25 samples along with an assessment of morphological characters and the habitats occupied. The genetic data collected from the Niue samples were analysed along with sequence data from GenBank based on previous studies of Microsorum in the Asia–Pacific region. Chloroplast data confirmed that M. grossum , M. membranifolium and M. scolopendria are present in Niue as monophyletic clades were recovered for each. The nuclear gapCp data revealed variation comprising both divergent paralogous loci and allelic diversity within loci, with some combinations shared among samples, indicating complex hybridisation involving M. grossum , M. papuanum and M. scolopendria . For some samples, their morphology, habitat and field identification did not correspond with their genetic characterisation, consistent with hybrid origin. Flow cytometry estimates of 2C DNA content (49.16–50.82 pg) did not provide evidence of recent allopolyploidy, indicating that variation observed in gapCp does not reflect differences in chromosome number. Notes on the species habitats and recognition in Niue are presented, including a dichotomous key.