Satellite-DNA evolutionary patterns under a complex evolutionary scenario: The case of Acrolophus subgroup (Centaurea L., Compositae) from the western Mediterranean Víctor N. Suárez-Santiago a , Gabriel Blanca a , Manuel Ruiz-Rejón b , Manuel A. Garrido-Ramos b, ⁎ a Departamento de Botánica, Facultad de Ciencias, Universidad de Granada, Granada, Spain b Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Granada, Spain Received 29 May 2007; received in revised form 2 July 2007; accepted 2 September 2007 Received by M. Di Giulio Available online 12 September 2007 Abstract Within the genus Centaurea (subtribe Centaureinae, tribe Cardueae, Compositae) hybridizations and reticulate-evolution phenomena have widely been recognized. This is especially true in the taxa included in the subgroup Acrolophus from the western Mediterranean area, in which recurrent hybridizations of parapatric (“microallopatric”) lineages within the geographical range of a primary radiation have been suggested. The subgroup Acrolophus includes taxa from three sections (i.e. Acrolophus, Phalolepis and Willkommia), and, together with other subgroups, forms the named Jacea group (one of the three main groups into which Centaurea is divided). In this paper, we have studied the influence that the complex evolutionary scenario described for the Acrolophus subgroup from the western Mediterranean exerts on the evolutionary pattern of a satellite-DNA family, the HinfI family, which exists within the genomes of these taxa. To this end, we have analyzed the evolution of this satellite- DNA family in taxa from different taxonomic comparative levels: i) seven subspecies of the C. boissieri complex (one of which with two varieties) of the sect. Willkommia; ii) species of the sections Willkommia (10 species, 19 taxa), Acrolophus (two species), and Phalolepis (two species), all in the Acrolophus subgroup; iii) one external species to the Jacea group, C. granatensis from the group Acrocentron; iv) and species from other related genera from the Centaureinae subtribe (Phonus and Carthamus, both belonging to the Carthamus group). The influence of the suggested model for the origin and diversification of the Acrolophus subgroup is evidenced by the existence of three different HinfI satellite-DNA subfamilies coexisting in some genomes, and by the analysis that we have made by comparing site-by-site the transition stages in the process of concerted evolution between the sequences of the each subfamily. From this analysis, we can deduce that the HinfI repeated subfamilies evolved in a gradual manner, and that the different stages of concerted evolution fit quite well with the combined nuclear–chloroplast-DNA-deduced divergences and phylogeny of the subtribe Centaureinae. The HinfI satellite-DNA from the Carthamus species group (genera Carthamus and Phonus) and from the Acrocentron group (Centaurea granatensis) shows a high intraspecific conservation of the repeats, suggesting that the mechanisms producing concerted evolution have been efficient in these taxa. In addition, the comparison of individual nucleotide positions between related species shows a paucity in the spreading of variants in each subfamily with satellite-DNA divergence, an indication of a constant rate of homogenization of the repeated cluster. On the contrary, this trend is absent in the comparisons of the HinfI sequences from taxa of the subgroup Acrolophus. In this subgroup, we have found in this repetitive family similar representative average sequences for each taxon analyzed, polymorphic sites in each taxon being scant, most of them autapomorphic, representing early stages of genetic differentiation between taxa in the process of concerted evolution. The absence of concerted evolution was visualized by similar levels of intraspecific variation and interspecific divergence and by the lack of fixed species-diagnostic nucleotide sites. These facts might reflect the reticulate mode of evolution of Acrolophus. © 2007 Elsevier B.V. All rights reserved. Keywords: Satellite-DNA; Concerted evolution; Acrolophus; Centaurea; Reticulate evolution; Radiation Available online at www.sciencedirect.com Gene 404 (2007) 80 – 92 www.elsevier.com/locate/gene Abbreviations: A, adenosine; AMOVA, analysis of the molecular variance; bp, base pair; C, cytidine; CTAB, cetyl trimethyl ammonium bromide; dNTP, deoxyribonucleoside triphosphate; G, guanosine; HORs, higher-order repeats; ML, maximum likelihood; Myr, million years; NJ, Neighbor-Joining; ln, natural logarithm; rDNA, DNA coding for rRNA; sect., section; subsp., subspecies; T, thymidine; TIM+G, transitional model of nucleotide substitution with different base frequencies and the variable sites following a discrete gamma distribution; var., varity. ⁎ Corresponding author. Tel.: +34 958 243080; fax: +34 958 244073. E-mail address: mgarrido@ugr.es (M.A. Garrido-Ramos). 0378-1119/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.gene.2007.09.001