Molecular Evolution and Phylogeny of Leishmania
The genus Leishmania was first described in 1903. Various numbers of species have been described since then. Although recent hierarchical taxonomic schemes have increasingly used intrinsic characters to assign Leishmania organisms into different species,
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Introduction Phylogenetics is the study of evolutionary relatedness among various groups of organisms (e.g., species or populations), which is revealed, for example, through morphological data and molecular sequencing data. Taxonomy, the science of naming and classifying organisms, is enriched by phylogenetics, although both fields remain methodologically and logically distinct. The fields overlap, however, in the area of phylogenetic systematics – the science that reconstructs the pattern of evolutionary events that have led to the distribution and diversity of life. Modern phylogenetic studies with different molecular datasets have transformed our knowledge on evolution and, consequently, taxonomy. A new classification system of eukaryotes has been recently proposed based on data from modern morphological approaches, biochemical pathways, and molecular phylogenetics (Adl et al. 2005). Six basic groups of eukaryotes, similar to the traditional “kingdoms”, have been recognized, and the genus Leishmania has been assigned to the supergroup Excavata (Table 1), in a hierarchical classification system that has been adopted without formal rank designations. The genus Leishmania has also suffered hierarchical changes. Its position within the family Trypanosomatidae has been revised, the number of species belonging to
G. Sch€onian (*) Charite´ – Universit€atsmedizin Berlin, Institut f€ ur Mikrobiologie und Hygiene, Campus Charite´ Mitte, Dorotheenstraße 96, 10117 Berlin, Germany e-mail: [email protected] E. Cupolillo Laborato´rio de Pesquisa em Leishmaniose, Instituto Oswaldo Cruz-FIOCRUZ, Manguinhos, Rio de Janeiro, Brazil I. Mauricio Unidade de Parasitologia e Microbiologia Me´dicas, UEI Parasitologia Me´dica, Instituto de Higiene e Medicina Tropical, R. da Junqueira, 100 Lisboa, Portugal A. Ponte-Sucre et al. (eds.), Drug Resistance in Leishmania Parasites, DOI 10.1007/978-3-7091-1125-3_2, # Springer-Verlag Wien 2013
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Table 1 Taxonomic position of the Leishmania genus according to the classification by Adl et al. (2005) Supergroup Excavata Cavalier-Smith 2002, emend. Simpson 2003 (P?) First rank Euglenozoa Cavalier-Smith 1993, emend. Simpson 1997 Second rank Kinetoplastea Honigberg, 1963 Third rank Metakinetoplastina Moreira 2004 (R) Fourth rank Trypanosomatidae Kent 1880, emend. Moreira 2004 Genus Leishmania Ross, 1903 (P?) possibly paraphyletic, (R) group identified by small subunit SSU rRNA phylogenies
it is disputed, and geographically defined populations have been identified in different Leishmania species. A good definition of Leishmania species is crucial for correct diagnosis and prognosis of the disease as well as for making decisions regarding treatment and control measures. This is a fundamental issue since the severity of the clinical manifestations in immunocompetent patients varies with the infecting organism. Different Leishmania species cannot be distinguished by morphological criteria and have therefore been assigned to different species primarily based on clin
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