Application of the unified species concept reveals distinct lineages for disjunct endemics of the Brassica repanda (Brassicaceae) complex

Abstract

Species delimitation is an important issue in terms of conservation priorities, especially for narrow endemics under threat of extinction. The Alpine endemics Brassica repanda subsp. glabrescens and subsp. baldensis belong to a highly polymorphic species complex, although their disjunct distribution suggests favourable conditions for independent evolution. In the present study, we applied the unified species concept to test whether the endemics form distinct evolutionary lineages, both from one another and also from the remainder of the complex. Compliance with the criteria of monophyly, diagnosability, and genotypic clustering was examined, primarily by making use of amplified fragment length polymorphism data. Both endemics were indicated as monophyletic by phylogenetic analyses, and diagnostic characters were found for both taxa. Population structure analyses showed clear genetic discontinuity for each of the endemics, with little admixture among the clusters. This evidence indicates that the endemics have acquired multiple properties that satisfy each of the species criteria considered. Hence, we suggest the taxonomic recognition of B. baldensis and B. glabrescens as separate species. Comparative population genetics analyses show the lack of marked genetic structuring within either taxon, as well as low levels of heterozygosity. Conclusions on the status of threat and on recommended conservation actions are drawn. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 482–497.

Population Genetics Methods Applied to a Species Delimitation Problem: Endemic Trumpet Daffodils (NarcissusSectionPseudonarcissi) from the Southern Iberian Peninsula

“…In contrast, their usefulness in the delimitation of recently diverged taxa (shallow phylogenetics), identification of genetically homogeneous lineages within species complexes, and analyses of adaptive population divergence has been frequently documented (Scotti-Saintagne et al 2004;Meudt and Clarke 2007;Shaffer and Thomson 2007;Kropf et al 2009;Reeves and Richards 2011). In particular, our main findings corroborate earlier studies illustrating the practical value of combining AFLP markers and a population genetics approach for distinguishing distinct metapopulations and for taxonomic delimitation in recent plant radiations, closely related taxa, and/or morphologically cryptic species (Martínez-Ortega et al 2004;Joly and Bruneau 2007;Koopman et al 2008;Duminil et al 2012;Garrido et al 2012;Lega et al 2012;Slová k et al 2012) and also emphasize that a pertinent sampling strategy is crucial for a representative analysis of species boundaries (Taberlet et al 1998). It must be kept in mind, however, that definitive species recognition will depend on fulfilling other key requirements, including the identification of diagnostic criteria based on suitable morphological or functional features or the phylogenetic criterion of monophyly.…”

“…In particular, determination of plant species boundaries in recently diverged lineages is a common problem for evolutionary biologists be-1 Author for correspondence; e-mail: monica@ebd.csic.es. cause populations may have not been isolated long enough to accumulate differences, and both morphological and genetic markers would be likely to show low levels of differentiation (Whittall et al 2004;Shaffer and Thomson 2007;Schö nswetter et al 2009;Lega et al 2012;Slová k et al 2012). An alternative and powerful tool for delimiting the boundaries of closely related taxa in complex groups of plants are population genetics approaches that rely on large sets of informative and independent genetic markers (Drummond and Hamilton 2007;Joly and Bruneau 2007;Kučera et al 2008;Duminil and di Michele 2009;Duminil et al 2012).…”

Wheat curl mite and dry bulb mite: untangling a taxonomic conundrum through a multidisciplinary approach

“…Although it has been assumed that this confusion dissipated almost 20 years ago (Navia et al ., ), some studies continued to make this mistake (Al‐Azzazy, Abdallah & El‐Kawas, ; Szczepaniec, ). Although precise delimitation and efficient separation of taxa is essential to many biological disciplines (Gwiazdowski et al ., ; Kaliontzopoulou et al ., ; Braby, Eastwood & Murray, ; Leavitt et al ., ; Lega et al ., ; Carstens & Satler, ; Marin et al ., ; Millar & Byrne, ), species identification remains a challenge in many different taxa (Bickford et al ., ; Birky et al ., ; Hill et al ., ; Ahmadzadeh et al ., ; Höglund et al ., ; Rheindt, Cuervo & Brumfield, ), including eriophyoid mites (de Lillo et al ., ). Resolving the taxonomic confusion between WCM and DBM in particular recently took on additional urgency with the discovery that WCM itself comprises a species complex of genetically distinct lineages with variable pest potential (Skoracka et al ., 2013a); moreover, DBM is nested within this complex (Skoracka et al ., ; Miller et al ., ).…”

Species delimitation and hybrid identification of Acrocomia aculeata and A. totai by genetic population approach

“…Species recognition and delimitation represent strategic information for any biological discipline (Queiroz, 2007;Hey, 2006). However, obtaining this information can be a difficult task due to such events as hybridization, introgression, recent divergence, and low levels of morphological and genetic differentiation between species (Schönswetter et al 2009;Lega et al 2012;Slovák et al 2012). In the genus Acrocomia, the classification of species is mainly based on their geographical distribution and morphology.…”