Molecular phylogeny: pitfalls and progress Autors/ores David Moreira UPRES-A 8080, Equipe Phylogénie et Evolution Moléculaires, Université Paris-Sud, France Hervé Philippe UPRES-A 8080, Equipe Phylogénie et Evolution Moléculaires, Université Paris-Sud, France Paraules clau: phylogeny, classification, long branch attraction, rRNA trees, sequence analysis Resum Molecular phylogeny based on nucleotide or amino acid sequence comparison has become a widespread tool for general taxonomy and evolutionary analyses. It seems the only means to establish a natural classification of microorganisms, since their phenotypic traits are not always consistent with genealogy. After an optimistic period during which comprehensive microbial evolutionary pictures appeared, the discovery of several pitfalls affecting molecular phylogenetic reconstruction challenged the general validity of this approach. In addition to biological factors, such as horizontal gene transfer, some methodological problems may produce misleading phylogenies. They are essentially (i) loss of phylogenetic signal by the accumulation of overlapping mutations, (ii) incongruity between the real evolutionary process and the assumed models of sequence evolution, and (iii) differences of evolutionary rates among species or among positions within a sequence. Here, we discuss these problems and some strategies proposed to overcome their effects. Descàrregues PDF (English) Publicat 2010-03-15 Número Vol. 3 Núm. 1 (2000) Secció Review Articles Llicència Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.