Macronuclear Plasticity in Two South American Populations of Spirostomum (Ciliophora, Heterotrichea) Warns About its Use for Species Classification: Revision and New Insights
| Autor: | Leonardo D. Fernández, Thiago da Silva Paiva, Pedro H. Campello-Nunes, Inácio Domingos da Silva-Neto, Noemi M. Fernandes, Carlos A. G. Soares |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Ciliate Macronucleus Phylogenetic tree biology Spirostomum Genetic Variation 030108 mycology & parasitology Ribosomal RNA South America biology.organism_classification Classification Microbiology 18S ribosomal RNA 03 medical and health sciences 030104 developmental biology Species Specificity Evolutionary biology Genus Taxonomy (biology) Ciliophora |
| Zdroj: | Protist. 172(2) |
| ISSN: | 1618-0941 |
| Popis: | Spirostomum is a widely distributed heterotrichean genus composed of well-known species with described ecology and phylogenetic affinities. The morphological classification of Spirostomum species is mostly based on the body size/shape, number of cortical granule rows and macronuclear characteristics. These features along with molecular phylogenies based on ribosomal genes divide the genus into two phylogroups, one including species with a compact macronucleus, and another including species with a moniliform macronucleus. Here, we present our observations on atypical Spirostomum specimens with unusually two distinct macronuclei and shortened adoral zone of membranelles. These atypical forms appeared in the cultures of S. minus and S. yagiui, sampled at different sites in South America (Chile and Brazil) and associated with unrelated substrate types. Morphological observations of living and stained cells, 18S rRNA gene analyses, and a thorough investigation of the literature suggest that the atypical phenotype may be a result of uncommon pathways during the conjugative process. Thus, we demonstrate that studies of ciliate natural populations and their morphological variations, especially from undersampled biogeographical regions, can reveal the boundaries of widely used morphological characters for Spirostomum taxonomy and species identification. |
| Databáze: | OpenAIRE |
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