http://elementy.ru/news?discuss=431954&return=1Одновременно опубликованы две работы, касающиеся филогении чешуйчатых (ящериц, змей, амфисбен и их родичей). Одна из них реконструирует молекулярную эволюцию ядерных генов, вторая — сравнивает морфологические признаки вымерших и ныне живущих представителей. Два филогенетических дерева оказались принципиально несхожи. В особенности это касается игуан, имеющих множество примитивных черт, но оказавшихся на молекулярном дереве среди своих продвинутых четвероюродных кузин. Этот методологический конфликт пока не удается разрешить.
http://sws.bu.edu/MSOREN/Wiens.pdfWar of the Iguanas: Conflicting Molecular and Morphological Phylogenies and Long-Branch Attraction in Iguanid Lizards
JOHN J. WIENS AND BRADFORD D. HOLLINGSWORTH
Abstract
Recent studies based on different types of data (i.e., morphology, molecules) have found
strongly conflicting phylogenies for the genera of iguanid lizards but have been unable to explain
the basis for this incongruence. We reanalyze published data from morphology and from the mito-
chondrial ND4, cytochrome b, 12S, and 16S genes to explore the sources of incongruence and re-
solve these conflicts. Much of the incongruence centers on the genus Cyclura, which is the sister
taxon of Iguana, according to parsimony analyses of the morphology and the ribosomal genes, but
is the sister taxon of all other Iguanini, according to the protein-coding genes. Maximum likelihood
analyses show that there has been an increase in the rate of nucleotide substitution in Cyclura in the
two protein-coding genes (ND4 and cytochrome b), although this increase is not as clear when par-
simony is used to estimate branch lengths. Parametric simulations suggest that Cycluramay be mis-
placed by the protein-coding genes as a result of long-branch attraction; even when Cyclura and
Iguana are sister taxa in a simulated phylogeny, Cyclura is still placed as the basal member of the
Iguanini by parsimony analysis in 55% of the replicates. A similar long-branch attraction problem
may also exist in the morphological data with regard to the placement of Sauromalus with the Galá-
pagos iguanas (Amblyrhynchus and Conolophus). The results have many implications for the analysis
of diverse data sets, the impact of long branches on parsimony and likelihood methods, and the use
of certain protein-coding genes in phylogeny reconstruction. [Data set incongruence; Iguanidae;
likelihood; long-branch attraction, parsimony.