BMC Evolutionary Biology BioMed Central Research article Open Access Timing major conflict between mitochondrial and nuclear genes in species relationships of Polygonia butterflies (Nymphalidae: Nymphalini) Niklas Wahlberg*1, Elisabet Weingartner2, Andrew D Warren3,4 and Sören Nylin2 Address: 1Laboratory of Genetics, Department of Biology, University of Turku, 20014 Turku, Finland, 2Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden, 3McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, SW 34th Street and Hull Road, PO Box 112710, Gainesville, FL 32611-2710, USA and 4Museo de Zoología, Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Apdo. Postal 70-399, México, DF 04510 México Email: Niklas Wahlberg* -
[email protected]; Elisabet Weingartner -
[email protected]; Andrew D Warren -
[email protected]; Sören Nylin -
[email protected] * Corresponding author Published: 7 May 2009 Received: 20 August 2008 Accepted: 7 May 2009 BMC Evolutionary Biology 2009, 9:92 doi:10.1186/1471-2148-9-92 This article is available from: http://www.biomedcentral.com/1471-2148/9/92 © 2009 Wahlberg et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: Major conflict between mitochondrial and nuclear genes in estimating species relationships is an increasingly common finding in animals. Usually this is attributed to incomplete lineage sorting, but recently the possibility has been raised that hybridization is important in generating such phylogenetic patterns.