36 research outputs found
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
On the origin of the invasive olives (Olea europaea L., Oleaceae).
The olive tree (Olea europaea) has successfully invaded several regions in Australia and Pacific islands. Two olive subspecies (subspp. europaea and cuspidata) were first introduced in these areas during the nineteenth century. In the present study, we determine the origin of invasive olives and investigate the importance of historical effects on the genetic diversity of populations. Four invasive populations from Australia and Hawaii were characterized using eight nuclear DNA microsatellites, plastid DNA markers as well as ITS-1 sequences. Based on these data, their genetic similarity with native populations was investigated, and it was determined that East Australian and Hawaiian populations (subsp. cuspidata) have originated from southern Africa while South Australian populations (subsp. europaea) have mostly derived from western or central Mediterranean cultivars. Invasive populations of subsp. cuspidata showed significant loss of genetic diversity in comparison to a putative source population, and a recent bottleneck was evidenced in Hawaii. Conversely, invasive populations of subsp. europaea did not display significant loss of genetic diversity in comparison to a native Mediterranean population. Different histories of invasion were inferred for these two taxa with multiple cultivars introduced restoring gene diversity for europaea and a single successful founder event and sequential introductions to East Australia and then Hawaii for cuspidata. Furthermore, one hybrid (cuspidata x europaea) was identified in East Australia. The importance of hybridizations in the future evolution of the olive invasiveness remains to be investigated
Comparative genomics of the major parasitic worms
Parasitic nematodes (roundworms) and platyhelminths (flatworms) cause debilitating chronic infections of humans and animals, decimate crop production and are a major impediment to socioeconomic development. Here we report a broad comparative study of 81 genomes of parasitic and non-parasitic worms. We have identified gene family births and hundreds of expanded gene families at key nodes in the phylogeny that are relevant to parasitism. Examples include gene families that modulate host immune responses, enable parasite migration though host tissues or allow the parasite to feed. We reveal extensive lineage-specific differences in core metabolism and protein families historically targeted for drug development. From an in silico screen, we have identified and prioritized new potential drug targets and compounds for testing. This comparative genomics resource provides a much-needed boost for the research community to understand and combat parasitic worms
Life history, climate and biogeography interactively affect worldwide genetic diversity of plant and animal populations.
Understanding how biological and environmental factors interactively shape the global distribution of plant and animal genetic diversity is fundamental to biodiversity conservation. Genetic diversity measured in local populations (GDP) is correspondingly assumed representative for population fitness and eco-evolutionary dynamics. For 8356 populations across the globe, we report that plants systematically display much lower GDP than animals, and that life history traits shape GDP patterns both directly (animal longevity and size), and indirectly by mediating core-periphery patterns (animal fecundity and plant dispersal). Particularly in some plant groups, peripheral populations can sustain similar GDP as core populations, emphasizing their potential conservation value. We further find surprisingly weak support for general latitudinal GDP trends. Finally, contemporary rather than past climate contributes to the spatial distribution of GDP, suggesting that contemporary environmental changes affect global patterns of GDP. Our findings generate new perspectives for the conservation of genetic resources at worldwide and taxonomic-wide scales
Substituição isolada da valva aórtica em pacientes com função ventricular deprimida Aortic valve replacement in patients with depressed left ventricular ejection fraction
Para avaliar o valor prognóstico da fração de ejeção do ventrículo esquerdo, entre 210 pacientes com lesões da valva aórtica operados, consecutivamente, entre maio de 1981 e outubro de 1988 e que receberam as próteses Omniscience e Meditronic-Hall, foram selecionados 112 e divididos, de acordo com a fração de ejeção do ventrículo esquerdo, em dois grupos: o G1 = FE > 40%, ficou com 52 pacientes com médias de idade 39 ± 12 anos, FE = 58 ± 10% e classe funcional (NYHA) = 2,8; o GE = FE < 40% ficou com 60 pacientes com médias de idade 48 ± 17 anos, FE = 27 ± 13% e (NYHA) = 3,6. Nas cirurgias, foram utilizados hipotermia e hemodiluição moderadas, oxigenador de bolhas, infusão cardioplégica St. Thomas. As médias dos tempos de circulação extracorpórea e parada cardíaca foram: no G1 =8 2 ± 18 e 49 ±7 minutos, e 96 ± 11 e 55 ± 6 minutos, no Grupo 2; o tamanho das próteses foi 25,2 ± 1,8 milímetros. No Grupo 1, a mortalidade imediata foi 3,8% no G1 e 5,8 no G2, e a tardia 4% no G1, e no G2 foi 8,7%. No G1 houve significante associação entre a mortalidade e a função ventricular sistólica. Clínicamente, no G1, 65% dos pacientes estão na (NYHA) I, 28% na II, 5% na III e 2% na IV. No G2, 46% estão na (NYHA) I, 25% na II, 13% na III, e 16% na IV. A sobrevida atuarial em sete anos foi 88 ± 2% no G1 e 76 ± 4% no G2. Portanto, os pacientes com FE < 40% apresentaram mortalidade mais elevada, menor sobrevida a curto e longo prazo e resultados clínicos menos satisfatórios. Para obtermos melhores resultados, devemos operar antes que a FE em repouso e exercício se torne deprimida, ou que apareça intolerância ao exercício moderado.<br>To evaluate the prognostic value of resting left ventricular ejection fraction (LVEF) a series of 210 consecutive patients with aortic valve disease operated upon between May 1981 and October 1988 was studied retrospectively. All patients had their aortic valve replaced by Omniscience or Meditronic prosthesis; 112 formed the study group because they have complete follow up and cineangiocardiographic data. Based on pre-operatory left ventricular ejection fraction the patients were divided in two groups: Group 1 = 52 patients with LVEF > 40%, 39 ± 12 years, NYHA functional class 2.8, and EF 58 ± 10%. Group 2 = 60 patients with LVEF < 40, 48 ± 17 years, NYHA functional class 3.6, and LVEF of 27 ± 12%. During surgery moderate hypothermia and hemodilution were utilized, with dubble oxygenator and cardioplegia With St. Thomas cardioplegic solution. Mean extracorporeal circulation and cardiac arrest time were respectively 82 ± 18 and 49 ± 7 minutes in Group 1 and 96 ± 11 and 55 ± 6 minutes in Group 2. The size of the prosthesis were 25.2 ± 1.8 mm in Group 1. The short term mortality was 3.8% in Group 1 and 5.8 in Group 2. The long-term mortality was 4.0% in Group 1 and 8.7% in Group 2. In Group 1 there was a significant association between mortality and left ventricular systolic function. In the follow-up evaluation, among patients in Group 1, 65% were in class I, 28% were in functional class II, 5% in class III, and 2% in class IV. Among patients in group II 46% were in class I, 25% in class II, 13% in class III, and 16% in class IV. The 7 year survival rate was 88 ± 2% in Group 1 and 76 ± 4% in Group 2. Thus, patients with LVEF less than 40% had higher short and longterm mortality and worse clinical course. For better surgical results patients with aortic valve disease should be operated upon before the reduction of left ventricular systolic function
Adding a third dimension to the edge of a species’ range: altitude and genetic structuring in mountainous landscapes
In addition to the topographical and ecological barriers, other landscape features may also subtly influence the patterns of gene flow and spatial genetic structuring at species’ borders. This paper focuses on the role played by altitudinal gradients that characterize mountainous landscapes. We formulate and test the hypothesis that when the distribution boundaries of plant species intersect mountainous landscapes, altitudinal gradients in ecological conditions may considerably enhance population subdivision and genetic structuring at the regional level. Using amplified fragment length polymorphism markers, we studied genetic diversity and differentiation in a set of 21 peripheral populations of the evergreen shrub Lavandula latifolia Med. (Labiatae) at its southernmost distribution limit in the Betic mountain ranges of southern Spain. Population size and abundance, and within-population genetic diversity, varied predictably with altitude, being highest at middle elevations
and declining steadily towards both the upper and lower altitudinal distribution margins. Genetic differentiation tended to follow the opposite trend. These altitudinal patterns result from variation with elevation in the relative influence of gene flow and drift on the distribution of genetic variation. Genetic drift prevails around the upper and lower altitudinal limits, whereas a situation closer to a drift-gene flow equilibrium exists at the center of the altitudinal distribution. Altitudinal variation in the relative influences of gene flow and drift appears as an essential element in the interpretation of regional genetic structuring of L. latifolia at its mountainous distribution edge, and a factor which may influence the evolutionary potential of peripheral populations and the likelihood of local adaptation.Peer reviewe