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دانلود رایکان مقاله انگلیسی ISI با موضوع طبقه بندی باکتری ها و آرکیا ها: برطبق گذشته، حال و آینده

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طبقه بندی باکتری ها و آرکیا ها: برطبق گذشته، حال و آینده

عنوان انگلیسی مقاله:

Classification of Bacteria and Archaea: Past, present and future

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Concepts of classification

In biology there are two quite different concepts for the classification of the organisms available. The theorybased model that is, for example, comparable to the biological species concept proposed by Ernst Mayr [25]. It is mainly applied to animals and some plants. It is based on an explicit and predictive theory of the mechanisms of speciation. Species are defined as groups of interbreeding natural populations that are reproductively isolated from other such groups. Such a model is currently not readily identifiable for microorganisms because there is a lack of understanding of the selection and diversity processes that may drive the creation of microbial species. A theory-based model for the classification of microorganisms would also have to take into account the effect of chemical, physical and functional boundaries on speciation. It should be based on cohesive evolutionary forces. A distinct taxonomic cluster should have evolved separately from other lineages.

Very recently, theory-based concepts have been proposed for the classification of bacteria, for instance, the ecotype-based approach [20] and the metapopulation concept [1]. However, both the approaches have severe drawbacks. From a conceptual standpoint, ecotype boundaries can only be established by elucidating the ecological niche of a strain. Moreover, some species encompass, on the one hand, multiple ecotypes and, on the other hand, there are also single ecotypes that can comprise multiple clusters of genotypes. Gene swapping is so frequent among prokaryotes that recombination, and not ecological adaptation, is the main cause of diversity [29]. The question is whether ecotypes are really true biological groupings.