Abstract 47
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| Weisse T., Moser M., Scheffel U., Stadler P., Berendonk T., Weithoff G., Berger H. (2012). Morphology, phylogenetic relationships, and pH response of two as yet undescribed Oxytricha species (Ciliophora, Hypotricha) - 31th Annual Meeting of the German Society of Protozoology, March 1-3, 2012, Wuppertal. Abstract on p. 110 of Abstract booklet. Poster (7 MB, PDF). Supported by the Austrian Science Fund; Project P-23425-B17. |
Morphology, phylogenetic relationships, and pH response of two as yet undescribed Oxytricha species (Ciliophora, Hypotricha)
a Institute for Limnology of the Austrian Academy of Sciences, 5310 Mondsee, Austria; b Technical University Dresden, Institute for Hydrobiology, 01062 Dresden, Germany; c Department of Ecology and Ecosystem Modelling, University of Potsdam, 14469 Potsdam, Germany; d Consulting Engineering Office for Ecology, Radetzkystrasse 10, 5020 Salzburg, Austria
We investigated the
morphology, phylogeny, and pH response of two undescribed Oxytricha
species isolated from two acid mining lakes (pH ~2.6) located
in Lusatia (Germany) and Langau (Austria). The Langau species,
tentatively named Oxytricha acidotolerans by Weisse et
al. (2011, Ecosphere), is about 60-80 × 25-40 µm
in life, has an ordinary 18-cirri pattern, about 24 adoral membranelles,
3 µm long dorsal bristles, three caudal cirri, two macronuclear
nodules, two micronuclei, and six dorsal kineties. The species
from Lusatia is highly variable in the main characters (body
size, shape, infraciliature, nuclear apparatus) making a useable
description almost impossible. Both species differ by 3% in their
SSU rDNA and occur in a cluster containing, inter alia, other
oxytrichids like Onychodromopsis flexilis, Cyrtohymena
citrina, and Paraurostyla weissei. However, Oxytricha
granulifera, the type species of Oxytricha, is distinctly
separated, demonstrating the immature taxonomy of this group.
Our ecological hypothesis was that the shape of the pH reaction
norm would not differ between our closely related species. Ciliate
growth rates measured in the laboratory were calculated from
changes in cell numbers vs. time. Results revealed a broad pH
niche for O. acidotolerans, with positive growth rates over the
entire pH range investigated, peaking at moderately acidic conditions
(pH 5.2). Cyst formation was positively and linearly related
to pH. Oxytricha sp. from Lusatia was more sensitive to
pH and did not survive at circum-neutral pH. Our experimental
results characterize O. acidotolerans as an acidotolerant
species, while Oxytricha sp. is acidophilic. We reject
our hypothesis that similar habitats would harbour ciliate species
with virtually identical pH reaction norm. Supported by the Austrian
Science Fund (FWF) Projects P20118-B17 (TW) and P23415-B17 (HB).
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Keywords: Hypotrichia, Ciliophora, ph, acid, limnology, Austria, Germany, Europe, ecology, adaptation, spirotricha
Dr Helmut BERGER
Consulting Engineering Office for Ecology - Technisches Büro für Ökologie
Radetzkystrasse 10, 5020 Salzburg, Austria, Europe
Phone +43-(0)662-432538; Fax +43-(0)662-443139; email office@protozoology.com; http://www.protozoology.com