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1

Molecular systematics: a synthesis of the common methods and the state of knowledge

100%
Mauro D. S., Agorreta A.
Cellular and Molecular Biology Letters
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2010
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tom 15
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nr 2
The comparative and evolutionary analysis of molecular data has allowed researchers to tackle biological questions that have long remained unresolved. The evolution of DNA and amino acid sequences can now be modeled accurately enough that the information conveyed can be used to reconstruct the past. The methods to infer phylogeny (the pattern of historical relationships among lineages of organisms and/or sequences) range from the simplest, based on parsimony, to more sophisticated and highly parametric ones based on likelihood and Bayesian approaches. In general, molecular systematics provides a powerful statistical framework for hypothesis testing and the estimation of evolutionary processes, including the estimation of divergence times among taxa. The field of molecular systematics has experienced a revolution in recent years, and, although there are still methodological problems and pitfalls, it has become an essential tool for the study of evolutionary patterns and processes at different levels of biological organization. This review aims to present a brief synthesis of the approaches and methodologies that are most widely used in the field of molecular systematics today, as well as indications of future trends and state-of-the-art approaches.
2

Molecular systematics of the Capoeta (Cypriniformes: Cyprinidae) species complex inferred from mitochondrial 16S rDNA sequence data

100%
Turan C.
Acta Zoologica Cracoviensia. Ser.A Vertebrata
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2008
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tom 51A
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nr 1-2
3
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Genetic variability of Euglena agilis [Euglenophyceae]

100%
Zakrys B., Empel J., Milanowski R., Gromadka R., Borsuk P., Kedzior M., Kwiatowski J.
Acta Societatis Botanicorum Poloniae
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2004
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tom 73
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nr 4
The results of the internal transcribed spacer (ITS2) of extrachromosomal rDNA and the chloroplast SSU rDNA sequence analysis presented here confirmed elevated genetic polymorphism revealed earlier by RFLP and RAPD for seven clones of the cosmopolitan species - Euglena agilis Carter. High diversity among these clonal strains was not reflected by morphological criteria, with the exception of the only one character - the ability of the cell in its non-motile dividing states (palmella) to produce mucus and form a slimy envelope. Evolutionary adaptation as formation of slimy envelope may be attributed to different survival strategy of the species by which it adapts to life in a highly variable environment.
4

Variation of mitochondrial DNA in the Hipposideros caffer complex (Chiroptera: Hipposideridae) and its taxonomic implications

80%
Vallo P., Guillen-Servent A., Benda P., Pires D. B., Koubek P.
Acta Chiropterologica
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2008
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tom 10
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nr 2
The Afrotropical leaf-nosed bat Hipposideros caffer has been traditionally regarded as a complex of populations, currently pertaining to two recognized cryptic species, H. caffer and H. ruber. Extent of distribution and morphological variation of these bats has raised concerns over whether the current perception of the complex reflects true phylogenetic relationships and taxonomic diversity. Our phylogenetic analysis of nucleotide sequences of the mitochondrial cytochrome b gene challenged the hypothesis of two cryptic species. Instead of the two reciprocally monophyletic lineages expected, corresponding to the two species, we recovered four distinct lineages with deep internal divergences. Two sister clades within a lineage of bats of H. caffer represent respectively the nominotypical form H. c. caffer, restricted to Southern Africa, and H. c. tephrus, inhabiting the Maghreb, West Africa and the Arabian Peninsula. Geographical isolation and deep genetic divergence suggest species status of both the forms. Another lineage comprises specimens of both morphotypes from West and East Africa. It probably represents a distinct species but its taxonomic assignation remains obscure. A Central African lineage of H. ruber comprises two sister clades, which become sympatric in Cameroon. Their status has to be clarified with additional evidence, since nuclear gene flow might be taking place. A further divergent lineage with H. ruber morphotype, most probably representing another distinct species, is restricted to West Africa. Although all three genetic forms of H. ruber may correspond to named taxa, their proper taxonomic assignation has to be assessed by comparison with type material.
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