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Abstract Detail

Development and Structure

Mickle, James E [1], Coiro, Mario [2], Barone Lumaga, Maria Rosaria [3].

Habitat expansion without substantial niche shift in Stangeria.

Molecular based analyses have revolutionized our understanding of cycad evolution and phylogeny. Most importantly, molecular dating analyses have suggested that most of extant cycads species originated during the Miocene-Pliocene. Such recent radiation permits development of hypotheses on the interaction between recent environmental change and speciation in cycads. Stangeria eriopus was originally describes as a fern, and only the production of cones allowed its correct recognition as a cycad. Plants of this species present pinnate fern-like leaves with a prominent midrib, a subterranean, sometimes branching, trunk, and fleshy roots. Anatomical sections have shown that the pinnae midribs are comprised of several veins that seemingly diverge, originating dichotomizing lateral veins. This kind of structure may maximize light- gathering potential, which represents a useful adaptation to low-light conditions widespread under dense forest canopies. Also, the photosynthetic anatomy of the leaflet and some aspects of epidermal micromorphology seem to point toward a sophisticated adaptation to closed tropical environments. The appearance of open environments such as grassland veld after the last glacial period, then more intensely with anthropisation, opened new niches characterized by drier conditions with more intense solar radiation and frequent burning. This represented an opportunity for Stangeria to explore new ecological niches, for which it may have been preadapted. It is possible that characters that allow Stangeria to thrive in grassland are not dissimilar from those allowing ferns to survive in disturbed environments. Production of low-cost leaves, produced singularly and not in whorls result in reduced biological loss consequences for the plant. Moreover, the presence of underground buds kept, with high resprouting ability could further increase the ability of Stangeria to adapt to ecological constrains acting on a species otherwise highly adapted to a forest understory plant.

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1 - North Carolina State Universtiy, Department of Plant and Microbial Biology, Campus Box 7612, 2115 Gardner Hall, Raleigh, NC, 27695-7612, USA
2 - University of Zurich, Institute of Systematic Botany, Universitätstrasse 2, Zurich, 8092 , Switzerland
3 - Universita' di Napoli Federico II, Dipartimento di Biologia, Orto Botanico, via Foria 223, Napoli, 80139, Italy


Presentation Type: Poster
Session: P, Development and Structure: Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PDS005
Abstract ID:649
Candidate for Awards:None

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