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.

Identification of novel sources of genetic variation for the improvement of cold germination ability in upland cotton (Gossypium hirsutum)

“…For this reason, each of the alleles identified by the SSRs were treated as independent loci and were scored as dominant markers. Allelic phenotypes based on the absence or presence of bands were scored as '1' and '0', respectively (López-Vinyallonga et al 2015). Descriptive statistics for the SSR markers including the number of different alleles (Na), number of effective alleles (Ne) and expected heterozygosity (He) were generated using GenAlEx v 6.5b3 (Peakall and Smouse 2012).…”

Microsatellite design for species delimitation and insights into ploidy for the Lake Baikal Cladophoraceae species flock

“…Although this reduces the potential informative power of SSRs, it is a convenient solution when the ploidy number is unknown and when the sorting of alleles cannot be resolved (García-Verdugo et al 2013;Obbard et al 2006;Pfeiffer et al 2011). In addition, some other properties of the population such as the total number of alleles and number of private alleles within populations are not affected (López-Vinyallonga et al 2015). This approach proved to be informative for Baikalian Cladophoraceae as our analyses showed diversity within the microsatellite markers, and the number of private alleles confirms that these markers have enough power to discriminate between most morphospecies regardless of the unknown ploidy level.…”

Genetic data support reproductively isolated species in the endemic Cladophoraceae (Chlorophyta) of Lake Baikal, Russia

“…Common statistics designed for microsatellites such as F st , expected heterozygosity, or linkage disequilibrium, are based on diploid individuals and cannot be used in polyploids if the allele dosage is uncertain or if the ploidy level is high (Bruvo et al 2004;Obbard et al 2006;Pfeiffer et al 2011;García-Verdugo et al 2013). To overcome this problem, alleles were coded into a binary presence (1)-absence (0) matrix as 'allele phenotypes', an approach successfully used in population genetics of many taxa (Andreakis et al 2009;Cidade et al 2013;López-Vinyallonga et al 2015;Samah et al 2016;Sampson & Byrne 2012). In spite of the reduction of informative power, this approach allows analysis of polyploids and the combination of individuals with different ploidy levels (Andreakis et al 2009;Bruvo et al 2004).…”

“…In spite of the reduction of informative power, this approach allows analysis of polyploids and the combination of individuals with different ploidy levels (Andreakis et al 2009;Bruvo et al 2004). Other statistics, such as total number of alleles per locus and number of private alleles are not affected (López-Vinyallonga et al 2015). Loci for which alleles failed to amplify in particular samples were coded as missing data.…”