Abstract Detail

Pteridological Section/AFS

Barrington, David [1].

A world-level phylogenetic and biogeographic perspective on the fern genus Polystichum.

With improved sampling and added markers, a largely resolved chloroplast-based phylogeny of Polystichum for the world is at last in hand. In the context of this phylogeny, an array of hypotheses for the biogeographic history of the genus can be assessed. The controversy as to the sister genus of Polystichum is resolved in favor of Cyrtomium s.s., which with evidence from the first divergences within the genus (e.g. isolation of the common ancestors of sect. Xiphopolystichum and subg. Haplopolystichum), confirm the hypothesized eastern-Asian origin of Polystichum. The genus as now circumscribed has at the moment 380 species; the greatest numbers are in temperate Eastern Asia (about 170 endemic species) and tropical America (over 60 endemic species). Both of these regions host arrays of newly diverged diploid species. Old autochthonous lineages have yielded the East-Asian novelties, but Polystichum has only recently reached the continental regions of the Americas where the recent neotropical radiations have taken place.  The phylogeny reveals that virtually all Austral species of Polystichum (including southern South American, southern African, Australian, and New Zealand species) have a common ancestor of relatively recent origin, leading to the explicit rejection of Copeland’s Antarctic origin hypothesis for the genus as a whole.  None of these taxa are diploid, suggesting that a relatively ancient set of poyploidization events yielded austral diversity. By contrast, neopolyploidy (the progenitors persisting) is most common in North-Temperate regions such as western North America and eastern Asia.

1 - University Of Vermont, Jeffords Hall, 63 Carrigan Drive, Burlington, VT, 05405, USA

Keywords:
Polystichum
Biogeography
polyploidy.

Presentation Type: Oral Paper:Papers for Sections
Session: 12
Location: Pines North/Boise Centre
Date: Monday, July 28th, 2014
Time: 4:15 PM
Number: 12011
Abstract ID:291
Candidate for Awards:None