Developmental and Structural Section
Graham, Linda , Arancibia, Patricia , Taylor, Wilson , Strother, Paul , Cook, Martha .
Aeroterrestrial Coleochaete (Streptophyta, Coleochaetales) Models Early Plant Adaptation to Land.
The streptophyte water-to-land transition was a pivotal event in Earth history but it is poorly understood. While some early-diverging modern streptophyte algae are aeroterrestrial (capable of living in subaerial habitats), Coleochaete, identified by some as sister to the embryophytes, is generally regarded as obligately aquatic. We tested the ability of two Coleochaete species to grow and reproduce asexually in non-aquatic subaerial conditions. We assessed the ability of aeroterrestrial Coleochaete to resist chemical degradation - a trait indicative of fossilization potential. When grown on agarized mineral media or on quartz sand, Coleochaete occurred as distinctive hairless multistratose hemispherical bodies having unistratose lobes or irregular clusters of cells with thick, layered chemically resistant walls. When exposed to liquid water, aeroterrestrial Coleochaete produced typical asexual propagules (biflagellate zoospores). Cells that had been air-dried for periods up to several months maintained their integrity and retained their green pigmentation. Structural and reproductive features of modern aeroterrestrial Coleochaete suggest that ancient complex streptophyte algae could have grown and reproduced in moist terrestrial habitats, persisted through periods of desiccation, and left distinctive fossilizable remains.
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1 - University Of Wisconsin, Botany Dept, 211 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
2 - UNIVERSIDAD DEL BIO-BIO, DEPTO DE CIENCIAS BASICAS, CHILLAN, Chile
3 - UNIVERSITY OF WISCONSIN - EAU CLAIRE, DEPT OF BIOLOGY-PHILLIPS HALL, 105 Garfield Avenue, P.O. Box 4004, EAU CLAIRE, WI, 54702-4004, USA
4 - Boston College, Paleobotany Laboratory, Weston Observatory, 381 Concord Road, Weston, MA, 02493, USA
5 - Illinois State University, School of Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Portland Room/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 8:30 AM