Increased genetic divergence between two closely related fir species in areas of range overlap

Because of introgressive hybridization, closely related species can be more similar to each other in areas of range overlap (parapatry or sympatry) than inareas where they are geographically isolated from each other (allopatry). Here,we report the reverse situation based on nuclear genetic divergence betweentwo fir species, Abies chensiensis and Abies fargesii, in China, at sites where they are parapatric relative to where they are allopatric. We examined genetic divergence across 126 amplified fragment length polymorphism (AFLP) markers in a set of 172 individuals sampled from both allopatric and parapatric populations of the two species. Our analyses demonstrated that AFLP divergence was much greater between the species when comparisons were made between parapatric populations than between allopatric populations. We suggest that selection in parapatry may have largely contributed to this increased divergenc

Natural Selection and Recombination Rate Variation Shape Nucleotide Polymorphism Across the Genomes of Three Related Populus Species

A central aim of evolutionary genomics is to identify the relative roles that various evolutionary forces have played in generating and shaping genetic variation within and among species. Here we use whole-genome resequencing data to characterize and compare genome-wide patterns of nucleotide polymorphism, site frequency spectrum, and population-scaled recombination rates in three species of Populus: Populus tremula, P. tremuloides, and P. trichocarpa. We find that P. tremuloides has the highest level of genome-wide variation, skewed allele frequencies, and population-scaled recombination rates, whereas P. trichocarpa harbors the lowest. Our findings highlight multiple lines of evidence suggesting that natural selection, due to both purifying and positive selection, has widely shaped patterns of nucleotide polymorphism at linked neutral sites in all three species. Differences in effective population sizes and rates of recombination largely explain the disparate magnitudes and signatures of linked selection that we observe among species. The present work provides the first phylogenetic comparative study on a genome-wide scale in forest trees. This information will also improve our ability to understand how various evolutionary forces have interacted to influence genome evolution among related species

QTL mapping of the narrow-branch "Pendula" phenotype in Norway spruce (Picea abies L. Karst.)

Pendula-phenotyped Norway spruce has a potential forestry interest for high-density plantations. This phenotype is believed to be caused by a dominant single mutation. Despite the availability of RAPD markers linked to the trait, the nature of the mutation is yet unknown. We performed a quantitative trait loci (QTL) mapping based on two different progenies of F1 crosses between pendula and normal crowned trees using NGS technologies. Approximately 25% of all gene bearing scaffolds of Picea abies genome assembly v1.0 were mapped to 12 linkage groups and a single QTL, positioned near the center of LG VI, was found in both crosses. The closest probe markers placed on the maps were positioned 0.82 cm and 0.48 cm away from the Pendula marker in two independent pendula-crowned x normal-crowned wild-type crosses, respectively. We have identified genes close to the QTL region with differential mutations on coding regions and discussed their potential role in changing branch architecture

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El artículo forma parte de una sección de la revista dedicada al intercambio de experiencias. - Resumen basado en el de la revista.Propuesta educativa que refleja la doble función que se pretende conferir al teléfono móvil en el contexto educacional: ser un dispositivo portátil y su posibilidad de comunicación inalámbrica para descubrir elementos del paisaje autóctono. Estamos ante una experiencia de aprendizaje cooperativo promovida en un instituto de Burgos que pretende estimular el espíritu investigador del alumno, así como potenciar la adquisición de la competencia social y ciudadana, con valores morales y solidarios, intrínsecos a la faceta cultural del entorno del discente. Se ha desarrollado en el marco de una yincana cultural, en la que el teléfono móvil sirve como medio de comunicación, obtención de información y documentación..CataluñaConsejería de Educación, Formación y Empleo. Servicio de Publicaciones y Estadística; Avda. de la Fama, 15 - 1ª Planta; 30006 Murcia; Tel. +34968279685; Fax +34968279835; [email protected]

Whole-genome resequencing facilitates the development of a 50K single nucleotide polymorphism genotyping array for Scots pine (Pinus sylvestris L.) and its transferability to other pine species

Scots pine (Pinus sylvestris L.) is one of the most widespread and economically important conifer species in the world. Applications like genomic selection and association studies, which could help accelerate breeding cycles, are challenging in Scots pine because of its large and repetitive genome. For this reason, genotyping tools for conifer species, and in particular for Scots pine, are commonly based on transcribed regions of the genome. In this article, we present the Axiom Psyl50K array, the first single nucleotide polymorphism (SNP) genotyping array for Scots pine based on whole-genome resequencing, that represents both genic and intergenic regions. This array was designed following a two-step procedure: first, 192 trees were sequenced, and a 430K SNP screening array was constructed. Then, 480 samples, including haploid megagametophytes, full-sib family trios, breeding population, and range-wide individuals from across Eurasia were genotyped with the screening array. The best 50K SNPs were selected based on quality, replicability, distribution across the draft genome assembly, balance between genic and intergenic regions, and genotype-environment and genotype-phenotype associations. Of the final 49 877 probes tiled in the array, 20 372 (40.84%) occur inside gene models, while the rest lie in intergenic regions. We also show that the Psyl50K array can yield enough high-confidence SNPs for genetic studies in pine species from North America and Eurasia. This new genotyping tool will be a valuable resource for high-throughput fundamental and applied research of Scots pine and other pine species

The Norway spruce genome sequence and conifer genome evolution

Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinus sylvestris, Abies sibirica, Juniperus communis, Taxus baccata and Gnetum gnemon reveals that the transposable element diversity is shared among extant conifers. Expression of 24-nucleotide small RNAs, previously implicated in transposable element silencing, is tissue-specific and much lower than in other plants. We further identify numerous long (>10,000 base pairs) introns, gene-like fragments, uncharacterized long non-coding RNAs and short RNAs. This opens up new genomic avenues for conifer forestry and breeding