Geographic genetic structure of Iberian columbines (gen. Aquilegia)

Southern European columbines (genus Aquilegia)are involved in active processes of diversification, and the Iberian Peninsula offers a privileged observatory to witness the process. Studies on Iberian columbines have provided significant advances on species diversification,but we still lack a complete perspective of the genetic diversification in the Iberian scenario. This work explores how genetic diversity of the genus Aquilegia is geographically structured across the Iberian Peninsula. We used Bayesian clustering methods, principal coordinates analyses, and NJ phenograms to assess the genetic relationships among 285 individuals from 62 locations and detect the main lineages. Genetic diversity of Iberian columbines consists of five geographically structured lineages, corresponding to different Iberian taxa. Differentiation among lineages shows particularly complex admixture patterns at Northeast and highly homogeneous toward Northwest and Southeast. This geographic genetic structure suggests the existence of incomplete lineage sorting and interspecific hybridization as could be expected in recent processes of diversification under the influence of quaternary postglacial migrations. This scenario is consistent with what is proposed by the most recent studies on European and Iberian columbines, which point to geographic isolation and divergent selection by habitat specialization as the main diversification drivers of the Iberian Aquilegia complex

Chloroplast DNA and isozyme analysis of the progenitor-derivative species relationship between <em>Senecio nebrodensis</em> L. and <em>S. viscosus</em> L.

A comparison of chloroplast DNA (cpDNA) and isozyme diversity in Senecio nebrodensis L., a species restricted to certain mountain ranges in Spain, and S. viscosus L., a widespread ruderal species in Europe, revealed that S. viscosus possessed the more common of two cpDNA haplotypes resolved in S. nebrodensis and contained only a small subset of the alleles found in S. nebrodensis at enzyme coding loci. The two species shared one restriction length mutation and one site mutation in their cpDNA, which distinguished them from other European Senecio species examined previously. Taken overall, these results support the hypothesis that S. nebrodensis and S. viscosus are related as a progenitor-derivative pair of species. The fact that no novel alleles were found in S. viscosus would suggest a relatively recent origin of the species, most probably in late glacial or postglacial times.</p

Origins of Plant Diversity in the California Floristic Province

Recent biogeographic and evolutionary studies have led to improved understanding of the origins of exceptionally high plant diversity in the California Floristic Province (CA-FP). Spatial analyses of Californian plant diversity and endemism reinforce the importance of geographically isolated areas of high topographic and edaphic complexity as floristic hot spots, in which the relative influence of factors promoting evolutionary divergence and buffering of lineages against extinction has gained increased attention. Molecular phylogenetic studies spanning the flora indicate that immediate sources of CA-FP lineages bearing endemic species diversity have been mostly within North Americamdashespecially within the west and southwestmdasheven for groups of north temperate affinity, and that most diversification of extant lineages in the CA-FP has occurred since the mid-Miocene, with the transition toward summer-drying. Process-focused studies continue to implicate environmental heterogeneity at local or broad geographic scales in evolutionary divergence within the CA-FP, often associated with reproductive or life-history shifts or sometimes hybridization