Molecular biogeography of prickly lettuce (lactuca serriola l.) shows traces of recent range expansion

Prickly lettuce (Lactuca serriola L., Asteraceae), a wild relative of cultivated lettuce, is an autogamous species which greatly expanded throughout Western and Northern Europe during the last 2 centuries. Here, we present a large-scale biogeographic genetic analysis performed on a dataset represented by 2622 individuals from 110 wild European populations. Thirty-two maternally inherited chloroplast RFLP-markers and 10 nuclear microsatellite loci were used. Microsatellites revealed low genetic variation and high inbreeding coefficients within populations, as well as strong genetic differentiation between populations, which was in accordance with the autogamous breeding system. Analysis of molecular variance based clustering indicated the presence of 3 population clusters, which showed strong geographical patterns. One cluster occupied United Kingdom and part of Northern Europe, and characterized populations with a single predominant genotype. The second mostly combined populations from Northern Europe, while the third cluster grouped populations particularly from Southern Europe. Kriging of gene diversity for L. serriola corroborated northwards and westwards spread from Central (Eastern) Europe. Significant lower genetic diversity characterized the newly colonized parts of the range compared to the historical ones, confirming the importance of founder effects. Stronger pattern of isolation by distance was assessed in the newly colonized areas than in the historical areas (Mantel’s r = 0.20). In the newly colonized areas, populations at short geographic distances were genetically more similar than those in the historical areas. Our results corroborate the species’ recent and rapid northward and westward colonization from Eastern Europe, as well as a decrease of genetic diversity in recently established populations

Evidence for the Emergence of New Rice Types of Interspecific Hybrid Origin in West African Farmers' Fields

In West Africa two rice species (Oryza glaberrima Steud. and Oryza sativa L.) co-exist. Although originally it was thought that interspecific hybridization is impossible without biotechnological methods, progenies of hybridization appear to occur in farmer fields

The significance of genetic erosion for the extinction of locally endangered plant populations

The research described in this thesis and a parallel thesis (Ouborg, 1993) addressed the question whether genetic processes are involved in the probability of population extinction for two endangered plant species in The Netherlands: Scabiosa columbaria and Salvia pratensis. A basic question is whether the level of genetic variation is already diminished in small populations. At the allozyme level, both the degree of polymorphism and the mean observed number of alleles were positively correlated with population size. Moreover, the allozyme data showed significant genetic differentiation between populations. ... Zie: Summary

Data from: Molecular biogeography of prickly lettuce (Lactuca serriola L.) shows traces of recent range expansion

Prickly lettuce (Lactuca serriola L., Asteraceae), a wild relative of cultivated lettuce, is an autogamous species which greatly expanded throughout Western and Northern Europe during the last two centuries. Here we present a large-scale biogeographic genetic analysis performed on a dataset represented by 2622 individuals from 110 wild European populations. Thirty-two maternally inherited chloroplast RFLP-markers and ten nuclear microsatellite loci were used. Microsatellites revealed low genetic variation and high inbreeding coefficients within populations, as well as strong genetic differentiation between populations, which was in accordance with the autogamous breeding system. AMOVA-based clustering indicated the presence of three populations clusters, which showed strong geographical patterns. One cluster occupied United Kingdom and part of Northern Europe, and characterized populations with a single predominant genotype. The second mostly combined populations from Northern Europe, while the third cluster grouped populations particularly from Southern Europe. Kriging of gene diversity for L. serriola corroborated northwards and westwards spread from Central (Eastern) Europe. Significant lower genetic diversity characterized the newly colonised parts of the range compared to the historical ones, confirming the importance of founder effects. Stronger pattern of isolation by distance was assessed in the newly colonised areas than in the historical areas (Mantel’s r=0.20). In the newly colonised areas, populations at short geographic distances were genetically more similar than those in the historical areas. Our results corroborate the species’ recent and rapid northward and westward colonisation from Eastern Europe, as well as a decrease of genetic diversity in recently established populations

Model-based populations in the cucumber mega-population.

<p>(A) Delta K values for different numbers of populations assumed (K) in the STRUCURE analysis. (B) Classification of 3,342 accessions into three populations using STRUCTURE 2.3.1. The distribution of the accessions to different populations is indicated by the color code (P1: red, P2: yellow, P3: blue). Numbers on the y-axis show the subgroup membership, and the x-axis shows the different accession. (C) Unrooted Neighbor-Joining (NJ) tree of the 3,342 accessions. Bootstrap values are indicated at the major branches. (D) Principal Component Analysis (PCA) of the 1,026 accessions without missing SSR fingerprinting data. Color codes for each population and admixture are consistent in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046919#pone-0046919-g002" target="_blank">Figure 2C, 2D</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046919#pone-0046919-g003" target="_blank">Figure 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046919#pone-0046919-g004" target="_blank">Figure 4C</a>.</p