FWF project P20118 (T. Weisse)
Patterns and processes of adaptation and tolerance to low pH of
freshwater plankton
Summary
The goal of this international, cooperative research project was to study the extent and
ecological significance of intraspecific genetotypic and phenotypic variability of the
freshwater ciliate Meseres corlissi. We used this organism as a model of a rare species
to test the hypothesis that aquatic protists are globally distributed and that, therefore,
genotypic differences and phenotypic adaptations to local environmental conditions
should be neglegible. If this hypothesis is correct, biodiversity of free-living protists must
be relatively low. This research project combined, for the first time, molecular genetic,
morphological and ecophysiological methods to investigate the extent of genetic and
phenotypic variability among different isolates of M. corlissi; the isolates originated from
different habitats on 4 continents (Europe, Asia, Australia, and Central America). Our
results demonstrate that a low variablity (0-4 %) of the genes studied corresponded to a
moderate morphological (5-15 %) and to a high ecophysiological (10-100 %) variablity.
One Meseres clone isolated from China differed significantly at all study levels from all
other isolates, while other clones, not only between two different localities in Austria, but
also between geographically distant localities such as Austria and Australia, were virtually
identical. These findings suggest a potentially wide dispersal of some clones within this
species, but also a locally limited dispersal and the establishment of habitat-specific, local
adaptations of other clones. The latter emerged primarily at the ecophysiological study
level. The temperature response of the various Meseres populations showed distinct,
genetically fixed adaptations to the habitat of their origin. Our results imply that
biodiversity and biogeography of free-living protist have to be considered more
specifically than it was common practise until now.
We further investigated the hitherto unknown life strategy of M. corlissi within this
project. We expect that our detailed morphological and ecological results on the
formation of its resting stages (cystys) will serve as a model for similar future studies.
Collaboration partners:
Wilhelm Foissner, Dept. of Organismic Biology, Univ. of Salzburg, Austria
Helga Müller, Private Laboratory, Konstanz, Germany
Michaela Strüder-Kypke &Denis Lynn, Dept. of Integrative Biology, Univ. of Guelph,
Ontario, Canada
FWF project P20118 (T. Weisse)
Publications related to this project:
1.
Weisse, T. (2004). Meseres corlissi: a rare oligotrich ciliate adapted to warm
water and temporary habitats. Aquat. Microb. Ecol. 37: 75-83. PDF
2.
Foissner, W., Müller, H. & Weisse, T. (2005). The unusual, Lepidosomecoated resting cyst of Meseres corlissi (Ciliophora: Oligotrichea): Light and
scanning electron microscopy, cytochemistry. Acta Protozool. 44: 201-215.
3.
Foissner, W., (2005). The unusual, Lepidosome-coated resting cyst of
Meseres corlissi (Ciliophora: Oligotrichea): Transmission electron
microscopyand phylogeny. Acta Protozool. 44: 217-230.
4.
Müller, H., Foissner, W. & Weisse, T. (2006) The role of soil in the life cycle of
Meseres corlissi (Ciliophora: Oligotrichea): experiments with two clonal strains
from the type locality, an astatic meadow pond. Aquat. Microb. Ecol. 42: 199208. PDF
5.
Foissner, W., Pichler, M., Al-Rahsheid, K. & Weisse, T. (2006) The unusual,
Lepidosome-coated resting cyst of Meseres corlissi (Ciliophora: Oligotrichea):
encystment and genesis and release of the lepidosomes. Acta Protozool. 45:
323-338.
6.
Foissner, W. & Pichler, M. (2006) The unusual, Lepidosome-coated resting
cyst of Meseres corlissi (Ciliophora: Oligotrichea): Genesis of four complex
types of wall precursors and assemblage of the cyst wall. Acta Protozool. 45:
339-366
7.
Gächter E. and Weisse T. (2006) Local adaptation among geographically
distant clones of the cosmopolitan freshwater ciliate Meseres corlissi. I.
Temperature response. Aquat.Microb. Ecol. 45: 291-300. PDF
8.
Weisse, T., Scheffel, U., Stadler , P. & Foissner, W. (2007). Local adaptation
among geographically distant clones of the cosmopolitan freshwater ciliate
Meseres corlissi. II. Response to pH. Aquat. Microb. Ecol. 47: 289-297 PDF
9.
Müller, H. (2007) Live observation of excystment in the spirotrich ciliate
Meseres corlissi. Europ. J. Protistol. 43: 95-100
10.
Müller, H., Achilles-Day, U.E.M. &Day, J.G. (2008) Cryopreservation of resting
cysts of the freshwater ciliate Meseres corlissi by conventional two-step
methods and one-step vitrification ProtocolS. CryoLetters 29: 329-338.
FWF project P20118 (T. Weisse)
11.
Gächter, E. and Weisse, T. (2008): Long-term acclimation of growth rates in
the oligotrich freshwater ciliate Meseres corlissi. Verh. Internat. Verein. Limnol.
30: 218-222.
12.
Weisse, T., Strüder-Kypke, M., Berger, H. & Foissner, W. (2008): Genetic,
morphological, and ecological diversity of spatially separated clones of
Meseres corlissi Petz and Foissner, 1992 (Ciliophora, Spirotrichea). J.
Eukaryot. Microbiol. 55: 257-270.