120 research outputs found
Restoration of european habitats in mainland, Portugal, using commercial seed mixtures. Considerations for its management and conservation
Permanent mountain pastures include meadows and other perennial pastures of high ecological,
economic, cultural and scenic value. Increasing desertification limits the maintenance and conservation
of its biodiversity and the associated landscape mosaic. A restoration experiment in permanent high
altitude grasslands in Beira Alta (Centre East (CE) mainland Portugal) was made, by sowing adequate
cultivars of existing grass and legume species. The main objectives addressed were: (1) comparison of
floristic composition between reference communities included in the previous habitats and the improved
communities; (2) evaluation of the success of sowing adequate cultivars of autochthonous species; (3)
evaluation of the establishment of target species in terms of the maintenance of floristic composition of
reference. The experiment was carried out in 2014 on nine farms situated in Beira Alta (Guarda District)
and the phytosociological method was applied in the floristic surveys. The sown species with highest
percentage of soil cover were Trifolium subterraneum, Lolium multiflorum, Ornithopus sativus and Trifolium
vesiculosum. In the priority habitat 6220 it was observed a re-establishment of many species in their
original composition and a high cover of several cultivars of Trifolium subterraneum. These results highlight
the importance of using cultivars of autochthonous species in the improvement of altitude pasturesinfo:eu-repo/semantics/publishedVersio
The use and limits of ITS data in the analysis of intraspecific variation in Passiflora L. (Passifloraceae)
The discovery and characterization of informative intraspecific genetic markers is fundamental for evolutionary and conservation genetics studies. Here, we used nuclear ribosomal ITS sequences to access intraspecific genetic diversity in 23 species of the genus Passiflora L. Some degree of variation was detected in 21 of these. The Passiflora and Decaloba (DC.) Rchb. subgenera showed significant differences in the sizes of the two ITS regions and in GC content, which can be related to reproductive characteristics of species in these subgenera. Furthermore, clear geographical patterns in the spatial distribution of sequence types were identified in six species. The results indicate that ITS may be a useful tool for the evaluation of intraspecific genetic variation in Passiflora
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
Coalescent Simulations Reveal Hybridization and Incomplete Lineage Sorting in Mediterranean Linaria
We examined the phylogenetic history of Linaria with special emphasis on the Mediterranean sect. Supinae (44 species). We revealed extensive highly supported incongruence among two nuclear (ITS, AGT1) and two plastid regions (rpl32-trnLUAG, trnS-trnG). Coalescent simulations, a hybrid detection test and species tree inference in *BEAST revealed that incomplete lineage sorting and hybridization may both be responsible for the incongruent pattern observed. Additionally, we present a multilabelled *BEAST species tree as an alternative approach that allows the possibility of observing multiple placements in the species tree for the same taxa. That permitted the incorporation of processes such as hybridization within the tree while not violating the assumptions of the *BEAST model. This methodology is presented as a functional tool to disclose the evolutionary history of species complexes that have experienced both hybridization and incomplete lineage sorting. The drastic climatic events that have occurred in the Mediterranean since the late Miocene, including the Quaternary-type climatic oscillations, may have made both processes highly recurrent in the Mediterranean flora
Phylogenetic Reconstruction and DNA Barcoding for Closely Related Pine Moth Species (Dendrolimus) in China with Multiple Gene Markers
Unlike distinct species, closely related species offer a great challenge for phylogeny reconstruction and species identification with DNA barcoding due to their often overlapping genetic variation. We tested a sibling species group of pine moth pests in China with a standard cytochrome c oxidase subunit I (COI) gene and two alternative internal transcribed spacer (ITS) genes (ITS1 and ITS2). Five different phylogenetic/DNA barcoding analysis methods (Maximum likelihood (ML)/Neighbor-joining (NJ), “best close match” (BCM), Minimum distance (MD), and BP-based method (BP)), representing commonly used methodology (tree-based and non-tree based) in the field, were applied to both single-gene and multiple-gene analyses. Our results demonstrated clear reciprocal species monophyly for three relatively distant related species, Dendrolimus superans, D. houi, D. kikuchii, as recovered by both single and multiple genes while the phylogenetic relationship of three closely related species, D. punctatus, D. tabulaeformis, D. spectabilis, could not be resolved with the traditional tree-building methods. Additionally, we find the standard COI barcode outperforms two nuclear ITS genes, whatever the methods used. On average, the COI barcode achieved a success rate of 94.10–97.40%, while ITS1 and ITS2 obtained a success rate of 64.70–81.60%, indicating ITS genes are less suitable for species identification in this case. We propose the use of an overall success rate of species identification that takes both sequencing success and assignation success into account, since species identification success rates with multiple-gene barcoding system were generally overestimated, especially by tree-based methods, where only successfully sequenced DNA sequences were used to construct a phylogenetic tree. Non-tree based methods, such as MD, BCM, and BP approaches, presented advantages over tree-based methods by reporting the overall success rates with statistical significance. In addition, our results indicate that the most closely related species D. punctatus, D. tabulaeformis, and D. spectabilis, may be still in the process of incomplete lineage sorting, with occasional hybridizations occurring among them
Internal Transcribed Spacer 2 (nu ITS2 rRNA) Sequence-Structure Phylogenetics: Towards an Automated Reconstruction of the Green Algal Tree of Life
L). Some have advocated the use of the nuclear-encoded, internal transcribed spacer two (ITS2) as an alternative to the traditional chloroplast markers. However, the ITS2 is broadly perceived to be insufficiently conserved or to be confounded by introgression or biparental inheritance patterns, precluding its broad use in phylogenetic reconstruction or as a DNA barcode. A growing body of evidence has shown that simultaneous analysis of nucleotide data with secondary structure information can overcome at least some of the limitations of ITS2. The goal of this investigation was to assess the feasibility of an automated, sequence-structure approach for analysis of IT2 data from a large sampling of phylum Chlorophyta.Sequences and secondary structures from 591 chlorophycean, 741 trebouxiophycean and 938 ulvophycean algae, all obtained from the ITS2 Database, were aligned using a sequence structure-specific scoring matrix. Phylogenetic relationships were reconstructed by Profile Neighbor-Joining coupled with a sequence structure-specific, general time reversible substitution model. Results from analyses of the ITS2 data were robust at multiple nodes and showed considerable congruence with results from published phylogenetic analyses.Our observations on the power of automated, sequence-structure analyses of ITS2 to reconstruct phylum-level phylogenies of the green algae validate this approach to assessing diversity for large sets of chlorophytan taxa. Moreover, our results indicate that objections to the use of ITS2 for DNA barcoding should be weighed against the utility of an automated, data analysis approach with demonstrated power to reconstruct evolutionary patterns for highly divergent lineages
Flujo génico en Armeria (Plumbaginaceae) en la Península Ibérica: un esquema hipotético
Sobre un mapa de la Península Ibérica se simbolizan todos aquellos casos de flujo génico entre taxones del género Armeria que se han podido detectar por medio de datos morfológicos, ecológicos y biogeográficos. De acuerdo con la información disponible, la hibridación entendida en el sentido de STEBBINS da lugar a diferentes situaciones dependiendo, entre otros factores, de la persistencia del flujo y del valor adaptativo de los genotipos originados. Dichas situaciones van desde los casos en que el flujo es puramente esporádico hasta aquéllas en que tiene un claro significado adapiativo y ha conducido a la formación de razas hibridógenas.Al! cases of gene fiow within taxa of lberian Armeria detected by means morphological, ecological and biogeographical data, are symbolyzed on a map. According to the available information, hybridization in the sense of
STEBBINS leads to different situations depending, among other factors, on the persistence of gene flow and on the adaptive value of the genotypes originated. Such situations range from the cases in which the gene flow is sporadic to the ones in which it has a clear adaptive significance and has lead to the birth of new races
- …