title: The Polyploid Series of the Achillea millefolium Aggregate in the Iberian Peninsula Investigated Using Microsatellites.
abstract: The Achillea millefolium aggregate is one of the most diverse polyploid complexes of the Northern hemisphere and has its western Eurasian boundary in the Iberian Peninsula. Four ploidy levels have been detected in A. millefolium, three of which have already been found in Iberia (diploid, hexaploid and octoploid), and a fourth (tetraploid) reported during the preparation of this paper. We collected a sample from 26 Iberian populations comprising all ploidy levels, and we used microsatellite markers analyzed as dominant in view of the high ploidy levels. Our goals were to quantify the genetic diversity of A. millefolium in the Iberian Peninsula, to elucidate its genetic structure, to investigate the differences in ploidy levels, and to analyse the dispersal of the species. The lack of spatial genetic structure recovered is linked to both high levels of gene flow between populations and to the fact that most genetic variability occurs within populations. This in turn suggests the existence of a huge panmictic yarrow population in the Iberian Peninsula. This is consistent with the assumption that recent colonization and rapid expansion occurred throughout this area. Likewise, the low levels of genetic variability recovered suggest that bottlenecks and/or founder events may have been involved in this process, and clonal reproduction may have played an important role in maintaining this genetic impoverishment. Indeed, the ecological and phenologic uniformity present in the A. millefolium agg. in Iberia compared to Eurasia and North America may be responsible for the low number of representatives of this complex of species present in the Iberian Peninsula. The low levels of genetic differentiation between ploidy levels recovered in our work suggest the absence of barriers between them.
authors.affiliation: Botanic Institute of Barcelona (IBB-CSIC-ICUB), Pg. del Migdia, Barcelona, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: López-Vinyallonga
authors.affiliation: Department of Plant Biology, University of Barcelona, Barcelona, Spain.
authors.forename: Ignasi
authors.initials: I
authors.lastname: Soriano
authors.affiliation: Botanic Institute of Barcelona (IBB-CSIC-ICUB), Pg. del Migdia, Barcelona, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Susanna
authors.affiliation: Barcelona Botanical Garden (Consortium of the Museum of Natural History of Barcelona), Barcelona, Spain.
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Montserra
authors.affiliation: Laboratoire d'Ecologie Alpine, CNRS UMR 5553, Université Grenoble Alpes, Grenoble, France.
authors.forename: Cristina
authors.initials: C
authors.lastname: Roquet
authors.affiliation: Botanic Institute of Barcelona (IBB-CSIC-ICUB), Pg. del Migdia, Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Garcia-Jacas
mesh_terms: D031162:Achillea / Q000235:genetics*; D032461:Chromosomes, Plant; D016000:Cluster Analysis; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats; D011123:Polyploidy; D013030:Spain