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Abstract Detail


Pteridological Section/AFS

Barrington, David [1], Jorgensen, Stacy [1].

Recent developments in revealing the origins of the tropical alpine and montane forest allotetraploids in Costa Rican Polystichum.

Three Polystichum species in Costa Ricaare allotetraploids, all from high-montane forests and paramos. Two are endemic: Polystichum lilianiae Barrington (high-montane) combines the heritage of the widespread P. turrialbae with an unknown second species, whereas P.talamancanum (paramo) combines the heritage of the endemic P. concinnum with an unknown second progenitor. The remaining tetraploid is P. orbiculatum (Desv.)J. Remy & Fee (paramo). A prominent member of the central and northern Andean paramo communities, P. orbiculatum is found north of Costa Rica only on Volcan Tacana at the border between Mexico and Guatemala. Polystichum orbiculatum does not yet have identified living progenitors, but one of its progenitors is also the unknown second progenitor of P. talamancanum based on isozyme studies. Here we report our use of an analysis of concatenated cloned segments of the low-copy nuclear genes PGIc andgapCp to improve understanding of the ancestry of these three allotetraploids .Polystichum lilianiae indeed yields a genome sister to P. turrialbae. It appears to have as its second progenitor another species with relationships in boreotropical Mexico, P. hartwegii. Weconfirmed that P. talamancanum and its proposed progenitor P. concinnum have agenome in common. This genome resolveswith an array of indusiate Polystichum species with relations to boreotropica lMexico. One genome retrieved from P. orbiculatum is shared with P.talamancanum, confirming the shared ancestry inferred from isozyme analysis.This genome resolves with a lineage endemic to the central Andes. The second genome retrieved from P. orbiculatum resolves with the Central Andean diploids P. lehmannii s.s. and P. sodiroi. The three tetraploids combine genomes typical of the exindusiate Andean andindusiate Mexican Polystichum clades in the three possible ways: the fully indusiate P. lilianiae combines two Mexican lineages, the occasionally indusiate P. talamancanum combines a Mexican and an Andean lineage, and the exindusiate P. orbiculatum combines two Andean lineages.

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1 - University of Vermont, Plant Biology, Jeffords Hall, 63 Carrigan Drive, Burlington, VT, 05405, USA

Keywords:
hybridizaton
Polystichum
Single/low copy nuclear genes
ancestry
Polyploidy.

Presentation Type: Oral Paper:Papers for Sections
Session: 11
Location: Union E/Hyatt
Date: Monday, July 9th, 2012
Time: 2:15 PM
Number: 11004
Abstract ID:747


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