Species delimitation in Noccaea densiflora species complex (Brassicaceae) based on morphological and molecular data

Abstract

The accurate identification of an organism is the basis of all biological disciplines. Although there have been many different species concepts and methods proposed, researchers generally choose the most appropriate concept according to their interests. However, each species concept has both advantages and disadvantages. In such cases, an integrated concept based on evidence obtained from different species concepts and methods is suitable for the accurate delimitation of a species. The biggest dilemma of integrated species delimitation methods is the inconsistency between species concepts and methods. Herein, the congruency of the different concepts and methods was tested to reveal the relationship of the Noccaea densiflora species complex. nrITS, chloroplast trnL-F, and trnQ-5'rps16 regions were used for species delimitation using the multispecies coalescent model (MSC) as implemented in two developed Bayesian Methods. ITS and trnL-F regions were also used for TCS haplotype network analyses. In addition to morphological measurements from different populations and vouchers, specific bioclimatic data values were also used for the principal component analysis. Based on all of the analyses, it was determined that only one population of N. densiflora and and one of N. microstyla were clearly distinct, whereas the rest of the specimens remain taxonomically uncertain.