Molecular phylogeny of euglyphid testate amoebae (Cercozoa: Euglyphida) suggests transitions between marine supralittoral and freshwater/terrestrial environments are infrequent.
Marine and freshwater ecosystems are fundamentally different regarding many biotic and abiotic factors. The physiological adaptations required for an organism to pass the salinity barrier are considerable. Many eukaryotic lineages are restricted to either freshwater or marine environments. Molecular phylogenetic analyses generally demonstrate that freshwater species and marine species segregate into different sub-clades, indicating that transitions between these two environments occur only rarely in the course of evolution. It is, however, unclear if the transitions between freshwater and environments characterized by highly variable salinities, such as the marine supralittoral zone, are also infrequent. Here, we use testate amoebae within the Euglyphida to assess the phylogenetic interrelationships between marine supralittoral and freshwater taxa. Euglyphid testate amoebae are mainly present in freshwater habitats but also occur in marine supralittoral environments. Accordingly, we generated and analyzed partial SSU rRNA gene sequences from 49 new marine/supralittoral and freshwater Cyphoderiidae sequences, 20 sequences of the Paulinellidae, Trinematidae, Assulinidae, and Euglyphidae families as well as 21 GenBank sequences of unidentified taxa derived from environmental PCR surveys. Both the molecular and morphological data suggest that the diversity of Cyphoderiidae is strongly underestimated. The results of our phylogenetic analyses demonstrated that marine supralittoral and freshwater euglyphid testate amoeba species are segregated into distinct sub-clades, suggesting that transitions between these two habitats occurred only infrequently.
Heger
Thierry J
TJ
Ecosystem Boundaries Research Unit, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), CH-1015 Lausanne, Switzerland; Environmental Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), Station 2, CH-1015 Lausanne, Switzerland; Institute of Biology, University of Neuchâtel, CH-2009 Neuchâtel, Switzerland; Department of Zoology and Animal Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland; Departments of Zoology and Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Electronic address: thierry.heger@epfl.ch.
Mitchell
Edward A D
EAD
Ecosystem Boundaries Research Unit, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), CH-1015 Lausanne, Switzerland; Environmental Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), Station 2, CH-1015 Lausanne, Switzerland; Institute of Biology, University of Neuchâtel, CH-2009 Neuchâtel, Switzerland. Electronic address: edward.mitchell@unine.ch.
Todorov
Milcho
M
Institute of Zoology, Bulgarian Academy of Sciences, 1000 Sofia, Bulgaria. Electronic address: mtodorov@zoology.bas.bg.
Golemansky
Vassil
V
Institute of Zoology, Bulgarian Academy of Sciences, 1000 Sofia, Bulgaria. Electronic address: golemansky@zoology.bas.bg.
Lara
Enrique
E
Institute of Biology, University of Neuchâtel, CH-2009 Neuchâtel, Switzerland. Electronic address: enrique.lara@unine.ch.
Leander
Brian S
BS
Departments of Zoology and Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Electronic address: bleander@interchange.ubc.ca.
Pawlowski
Jan
J
Department of Zoology and Animal Biology, University of Geneva, Sciences III, CH-1211 Geneva 4, Switzerland. Electronic address: Jan.Pawlowski@unige.ch.
D056907:Cercozoa / Q000145:classification / Q000235:genetics* / Q000648:ultrastructure; D016054:DNA, Protozoan / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D005618:Fresh Water; D020459:Genes, rRNA; D008855:Microscopy, Electron, Scanning; D010802:Phylogeny; D012623:Seawater; D017422:Sequence Analysis, DNA
D016054:DNA, Protozoan; D004275:DNA, Ribosomal