title: Species delimitation without prior knowledge: DISSECT reveals extensive cryptic speciation in the Silene aegyptiaca complex (Caryophyllaceae).
abstract: Species delimitation is a major focus of biosystematics. In recent years, considerable progress has been achieved with the development of the multispecies coalescent (MSC) model, where species constitute the branches of the species tree or network. However, researchers are faced with the limitation that the MSC method of choice often requires a priori assignment of individuals to species. This not only introduces subjectivitiy into the analyses, but may also lead to meaningless species tree hypotheses, if the allele-to-species assignments are inaccurate. DISSECT is a recently introduced method that does not require a priori allele-to-species assignments, but instead examines the posterior probabilities of groupings (clusterings) of individuals under study. Using the DISSECT approach, we analysed genetic data from 75 individual plants belonging to the Silene aegyptiaca species complex that has previously been divided into 3-5 species. Marginal likelihood estimates from (*)BEAST analyses, run with predefined species classifications, strongly favour those compatible with the DISSECT result over those from morphology- and geography-based taxonomy. We found at least nine species, including several cryptic ones, for which no clear geographical or morphological patterns are correlated. However, the limited data and the possibility of unmodelled processes mean there is still much uncertainty about the true number of MSC species, and for taxonomic purposes, other criteria might be relevant. Nevertheless, we argue that the approach signifies an important step towards objective and testable species delimitations in any organismal group. In particular, it makes it possible to avoid biologically irrelevant species classifications.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden; Department of Biology, Faculty of Sciences, University of Dicle, 21280 Diyarbakir, Turkey. Electronic address: ilgimd@gmail.com.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Toprak
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden.
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Pfeil
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden.
authors.forename: Graham
authors.initials: G
authors.lastname: Jones
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden; Department of Plant Sciences, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway.
authors.forename: Thomas
authors.initials: T
authors.lastname: Marcussen
authors.affiliation: Department of Biology, Faculty of Sciences, University of Dicle, 21280 Diyarbakir, Turkey.
authors.forename: Alaattin Selçuk
authors.initials: AS
authors.lastname: Ertekin
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Oxelman
mesh_terms: D001499:Bayes Theorem; D005843:Geography; D016013:Likelihood Functions; D010802:Phylogeny; D011336:Probability; D029751:Silene / Q000145:classification*; D012984:Software; D013045:Species Specificity
keywords: DISSECT; Multispecies coalescent; S. aegyptiaca; Section Atocion; Silene; Species delimitation