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Abstract Detail


Evolutionary Developmental Biology (Evo-Devo)

Buzgo, Matyas [1], Lucas, Cran M [1], Miller, Annie Phanid [1], Witherington, Sarah [1].

Psilotaceae and Ophioglossaceae: odd twins, until you look twice.

Surprisingly in the eusporangiate ferns, molecular phylogeny places Psilotaceae next to the Ophioglossaceae, while the two differ greatly in morphology. Ophioglossaceae have a complex leaf that carries an extravagant sporophore, while Psilotaceae are considered to lack leaves, to bear very rudimentary sporangia directly on their aerial stems, and to lack roots. We show that the aerial structures of Psilotum are not at odds with molecular data, and Psilotum recalls the sporophores of Ophioglossaceae. We suggest that the aerial frond in Psilotum actually represents a leaf, or a stem organ identity that is irreversibly different from the subterranean stem. The multiplicity of sporophores reflects a homeotic evolutionary step involving modifications of the shoot apex meristem maintenance.

Broader Impacts:
Molecular phylogeny has increased our understanding of evolutionary relations, but also risen questions regarding the evolution of the non molecular features that are actually the target of selection, namely morphology and anatomy. Evolutionary Development (EvoDevo) addresses these questions, linking molecular evolution with the morphological and anatomical developmental pathways of organisms.
Namely in old lineages, great gaps have opened between molecular and morphological analysis, probably because of the long evolutionary history and extinctions. Among the ferns (Monilophytes), eusporangiate ferns represent ancestral stem group, but have lost many taxa. The two sister families Ophioglossaceae and Psilotaceae are particularly enigmatic. This study can shed light onto one of its biggest mysteries: the origin of leaves in ferns and seed plants.


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1 - Louisiana State University in Shreveport (LSUS), Biological Sciences, 1 University Place, Shreveport, LA, 71115, USA

Keywords:
Monilophyta
Psilotaceae
Ophioglossaceae
morphology
EvoDevo
organ identity
meristem maintenance
homeosis
Pteridophyta.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PEV002
Abstract ID:242


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