No abstract

New insights are provided regarding interspecific relationships, character evolution, and geographical origin and expansion of Capsicum A clearly distinct early-diverging clade can be distinguished, centred in western-north-western South America. Subsequent rapid speciation has led to the origin of the remaining clades. The diversification of Capsicum has culminated in the origin of the main cultivated species in several regions of South to Central America.

No abstract

Summary• Achillea , a temperate genus of herbaceous allogamous perennials, is a model for evolutionary radiation through hybridization and polyploidization.• AFLP analyses were performed on 300 individuals of 66 populations and 27 taxa/ cytotypes, mainly from the polyploid A. millefolium aggregate and its suspected hybrid links with other clades of the genus.• The mosaic genetic structure of hybrids and polyploids is revealed by specific AFLP bands shared with their assumed parents. In E Asia, A. alpina -4x and A. wilsoniana4x are allotetraploids between A. acuminata -2x (sect. Ptarmica ) and A. asiatica -2x (sect. Achillea-A. millefolium agg.). A. virescens -4x is a hybrid species linking A. nobilis agg. and A. millefolium agg. in S Europe. The hybrid swarm A. clypeolata2x × A. collina -4x recently formed in Bulgaria shows no AFLP bands additive to its parents; by contrast, other more ancient allopolyploids exhibit genetic innovations. Relationships within A. millefolium agg. are complex. Five 2x-taxa, mostly well separated and regressive, are limited to Eurasia; seven 4x-and 6x-taxa are intimately linked by hybridization, are expansive, and through A. asiatica -2x/4x have formed the N American polyploids.• All these results from AFLPs correspond well to other evidence, and indicate a long history of reticulate evolution in Achillea .

Flow cytometric measurements of nuclear DNA content were performed using ethidium bromide as the DNA stain (internal standard, Hordeum vulgare 'Ditta', 1C = 5.063 pg) in 25 samples belonging to nine diploid species and four varieties of Capsicum: C. chacoense, C. parvifolium, C. frutescens, C. chinense, C. annuum var. annuum, C. baccatum var. baccatum, C. baccatum var. pendulum, C. baccatum var. umbilicatum, C. eximium and C. pubescens, all with 2n = 24, and C. campylopodium with 2n = 26. In addition, one sample each of C. annuum var. annuum and C. pubescens were also analysed using Feulgen densitometry (standard, Allium cepa 'Stuttgarter Riesen', 1C = 16.75 pg). Both staining methods resulted in very similar relative values. Genome size displays significant variation between but not within species (except in C. campylopodium), and contributes to their taxonomic grouping. 1C-values range from 3.34-3.43 pg (3273-3361 Mbp) in C. chacoense and the C. annuum complex to 4.53-5.77 pg (4439-5655 Mbp) in C. campylopodium and C. parvifolium. The data obtained support conclusions on phylogenetic relationships in the genus derived from karyotype analyses using chromosome banding approaches. In Capsicum, constitutive heterochromatin amount is correlated with genome size, except in C. parvifolium, and is regarded as an additive genomic component.