High-Level Genetic Diversity but No Population Structure Inferred from Nuclear and Mitochondrial Markers of the Peritrichous Ciliate Carchesium polypinum in the Grand River Basin (North America)

• Published in: Applied and Environmental Microbiology Vol. 75; no. 10; pp. 3187 - 3195
• Main Authors: Gentekaki, E, Lynn, D.H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.05.2009; American Society for Microbiology (ASM)
• Subjects: Animals; Biological and medical sciences; Carchesium polypinum; Ciliophora; Cluster Analysis; cytochrome-c oxidase; DNA, Mitochondrial - chemistry; DNA, Mitochondrial - genetics; DNA, Protozoan - chemistry; DNA, Protozoan - genetics; DNA, Ribosomal - chemistry; DNA, Ribosomal - genetics; DNA, Ribosomal Spacer - chemistry; DNA, Ribosomal Spacer - genetics; Electron Transport Complex IV - genetics; Fresh Water - parasitology; Freshwater organisms; Fundamental and applied biological sciences. Psychology; genes; Genes, rRNA; Genetic diversity; Genetic Variation; Geography; Microbial Ecology; Microbiology; Molecular Sequence Data; Oligohymenophorea - classification; Oligohymenophorea - isolation & purification; Ontario; Peritrichia; Phylogeny; Population genetics; Population structure; Protozoa; Protozoan Proteins - genetics; Ribonucleic acid; ribosomal RNA; River basins; Rivers; RNA; RNA, Protozoan - genetics; RNA, Ribosomal - genetics; Sequence Analysis, DNA; watersheds; Ontario; Canada, Ontario; Canada, Ontario, Grand R; Population structure; Genetic diversity; Rivers
• ISSN: 0099-2240; 1098-5336; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.00178-09

Studies that assess intraspecific genetic variation in ciliates are few and quite recent. Consequently, knowledge of the subject and understanding of the processes that underlie it are limited. We sought to assess the degree of intraspecific genetic variation in Carchesium polypinum (Ciliophora: Peritrichia), a cosmopolitan, freshwater ciliate. We isolated colonies of C. polypinum from locations in the Grand River basin in Southwestern Ontario, Canada. We then used the nuclear markers--ITS1, ITS2, and the hypervariable regions of the large subunit rRNA--and an 819-bp fragment of the mitochondrial cytochrome c oxidase I gene (cox-1) to investigate the intraspecific genetic variation of C. polypinum and the degree of resolution of the above-mentioned markers at the population level. We also sought to determine whether the organism demonstrated any population structure that mapped onto the geography of the region. Our study shows that there is a high degree of genetic diversity at the isolate level, revealed by the mitochondrial markers but not the nuclear markers. Furthermore, our results indicate that C. polypinum is likely not a single morphospecies as previously thought.