Species diversity and reticulate evolution in the Asplenium normale complex (Aspleniaceae) in China and adjacent areas

Abstract

The Asplenium normale complex contains the widespread A. normale and several geographically restricted species: A. boreale, A. hobdyi, A. kiangsuense, A. oligophlebium and A. shimurae. The taxonomy of this group is unclear with some entities treated infraspecifically or as synonyms. Furthermore, the existence of diploids and tetraploids in this species complex is suggestive of reticulate evolution. In order to formulate a natural classification and to investigate the relationships in this complex, phylogenetic analyses of plastid and nuclear sequence data and inference of ploidy level were used to assess the distinctiveness of putative taxonomic units and their relationships. The Asplenium normale complex was recovered as a monophyletic group comprising six principal chloroplast lineages. The results support the hypothesis that A. normale s.l. contains several species. Based on our inferences, we outline an improved species classification recognizing three diploid and four tetraploid entities. Incongruence of chloroplast and nuclear phylogenies was interpreted to be a result of recurrent reticulation events in the A. normale complex.

Genome evolution of ferns: evidence for relative stasis of genome size across the fern phylogeny

“…We checked and assembled all published 1C-values of ferns using the Pteridophyte DNA C-values database (Bennett & Leitch, 2012) or recent publications (Ekrt et al, 2009;Bainard et al, 2011;Nitta et al, 2011;Williams & Waller, 2012;Bou Dagher-Kharrat et al, 2013;Chang et al, 2013;Dyer et al, 2013;Pustahija et al, 2013). The chromosome numbers of ferns were obtained from online databases (http://ccdb.tau.ac.il and http://chromosomes.binoz.uj.edu.pl/ chromosomes in August 2015, plus the unpublished database comprising all fern chromosome counts assembled by H.S.).…”

What We Do (and Don't) Know About Ferns: <I>Dryopteris</I> (Dryopteridaceae) as a Case Study

“…Both of these large genera include patterns of reticulate speciation that have been the focus of recent molecular studies, e.g. Schneider et al (2012), Dyer et al (2012), and Chang et al (2013) on Asplenium and Perrie et al (2003) on Polystichum. Schneider and colleagues' (2012) study of Asplenium using two low-copy nuclear markers plus ITS found conflict between the markers that they interpreted as evidence of ancient reticulation events.…”

“…, Elaphoglossum Schott ex J. Sm. (Vasco et al 2009;Ló riga et al 2013), Microgramma C. Presl (Salino et al 2008), Asplenium (Chang et al 2013), and Dryopteris (Zhang 2012;. But which tree should a group's classification system be based on?…”

Asplenium minutifolium (Aspleniaceae), a new species from Thailand

“…The species are widely distributed, from temperate to tropical regions (Boonkerd & Suksathan, 2009;Chang et al, 2013), are adapted to various environments, and are often epiphytic or epipetric (de Winter & Amoroso, 2003). In Thailand, 38 Asplenium species have been recorded (Boonkerd & Pollawatn, 2000;Boonkerd, 2009;Lindsay & Middleton, 2012 onwards;Lindsay et al, 2013).…”