Geographic variation among brown and grizzly bears (Ursus arctos) in North America / by E. Raymond Hall.

no.13 (1984)

Genome-wide patterns of latitudinal differentiation among populations of Drosophila melanogaster from North America.

Understanding the genetic underpinnings of adaptive change is a fundamental but largely unresolved problem in evolutionary biology. Drosophila melanogaster, an ancestrally tropical insect that has spread to temperate regions and become cosmopolitan, offers a powerful opportunity for identifying the molecular polymorphisms underlying clinal adaptation. Here, we use genome-wide next-generation sequencing of DNA pools ('pool-seq') from three populations collected along the North American east coast to examine patterns of latitudinal differentiation. Comparing the genomes of these populations is particularly interesting since they exhibit clinal variation in a number of important life history traits. We find extensive latitudinal differentiation, with many of the most strongly differentiated genes involved in major functional pathways such as the insulin/TOR, ecdysone, torso, EGFR, TGFβ/BMP, JAK/STAT, immunity and circadian rhythm pathways. We observe particularly strong differentiation on chromosome 3R, especially within the cosmopolitan inversion In(3R)Payne, which contains a large number of clinally varying genes. While much of the differentiation might be driven by clinal differences in the frequency of In(3R)P, we also identify genes that are likely independent of this inversion. Our results provide genome-wide evidence consistent with pervasive spatially variable selection acting on numerous loci and pathways along the well-known North American cline, with many candidates implicated in life history regulation and exhibiting parallel differentiation along the previously investigated Australian cline.

Impacte de la variabilitat climàtica ràpida de l'últim període glacial sobre la vegetació del sud-est de Nord Amèrica

Projecte de recerca elaborat a partir d’una estada a UMR-CNRS - Géologie et Océanographie, França, entre 2007 i 2009. Els canvis climàtics ràpids de l’últim període glacial (cicles Dansgaard/Oeschger i Heinrich Stadials-HS), han estat documentats en testimonis marins, de gel i dipòsits continentals, generalment de l’hemisferi nord. Mentre que la majoria dels estudis paleoclimàtics i paleoceanogràfics de l’Atlàntic Nord sobre l’últim període glacial s’han centrat en la part nord i est, les latituds mitjanes de la part occidental han estat menys estudiades. Particularment, els canvis de la vegetació de l’est de Nord Amèrica durant l’últim glacial es coneixen molt poc degut a la manca de seqüències pol.líniques llargues en aquesta regió. Només dues seqüències de pol.len del llac Tulane (Florida) mostren canvis de la vegetació significatius i interessants durant l’últim glacial, que suggereixen HS càlids i humits, que contrasta amb el que s’observa a l’altre costat de l’Atlàntic Nord. El treball realitzat al UMR-CNRS 5805 EPOC, Université Bordeaux 1, EPHE, des del 23 d’abril 2007 al 22 d’abril 2009, gràcies a la beca Beatriu de Pinós, implica una reconstrucció a alta resolució dels canvis de la vegetació a partir de l’anàlisi d’un testimoni marí, localitzat a l’oest de l’Atlàntic Nord subtropical (MD99-2203, 34º58’N, 75º12’W), durant l’Estadi Isotòpic Marí 3 (MIS 3). Les dades pal.linològiques del testimoni mostren una alternança entre Picea i Quercus. En general, les associacions pol.líniques indiquen que les variacions de la vegetació segueixen un patró bosc boreal/temperat durant l’últim glacial. El model d’edat preliminar basat en edats radiomètriques suggereix un augment del bosc temperat acompanyat d’una reducció del boreal entre el H4 i el H3. La comparació amb registres pol.línics marins d’alta resolució de la regió est subtropical, a latituds similars, mostren, per primer cop, que els canvis en les formacions forestals associats als canvis climàtics ràpids de l’últim glacial van ser menys intensos al sud-est de Nord Amèrica que a la Península Ibèrica.

The composition of mineral waters sourced from Europe and North America in respect to bone health: composition of mineral water optimal for bone.

The consumption of mineral waters is increasing in industrialised countries. High intakes of Ca and other alkalising cations as well as a low acid intake are beneficial to bone. We examined which components of mineral waters are conditioning their Ca content and their alkalinising power, in order to define the optimal profile. European mineral waters were randomly selected on the Internet: 100 waters with less than 200 mg Ca/l (9.98 mEq/l) and fifty with more than 200 mg/l, all with complete data for SO4, P, Cl, Na, K, Mg and Ca, and most also for HCO3. For comparison, forty North American mineral waters were randomly chosen. The potential renal acid load (PRAL) was calculated for each mineral water. North American waters did not reveal significant results because of their low mineralisation. We performed correlations between all eight components in order to explore the properties of the mineral waters. In the European waters, twenty-six out of twenty-eight correlations showed a P value of <or= 0.01. In waters with PRAL >0 (acidifying waters), PRAL was positively correlated with SO4, Ca, K and Mg (P < 0.001). In those with PRAL < 0 (alkalinising waters), PRAL was negatively correlated with HCO3, Na, Mg, Ca, K, Cl and SO4 (P < 0.001). SO4 and HCO3 were not found together in high quantities in the same water for geochemical reasons. A high Ca content is associated with either a high SO4 or a high HCO3 content. SO4 theoretically increases Ca excretion, while HCO3 and low PRAL values are associated with positive effects on bone. Therefore, the best waters for bone health are rich in both HCO3 and Ca, and by consequence low in SO4.

The Caribbean-North America-Cocos Triple Junction and the dynamics of the Polochic-Motagua fault systems: Pull-up and zipper models

The Polochic-Motagua fault systems (PMFS) are part of the sinistral transform boundary between the North American and Caribbean plates. To the west, these systems interact with the subduction zone of the Cocos plate, forming a subduction-subduction-transform triple junction. The North American plate moves westward relative to the Caribbean plate. This movement does not affect the geometry of the subducted Cocos plate, which implies that deformation is accommodated entirely in the two overriding plates. Structural data, fault kinematic analysis, and geomorphic observations provide new elements that help to understand the late Cenozoic evolution of this triple junction. In the Miocene, extension and shortening occurred south and north of the Motagua fault, respectively. This strain regime migrated northward to the Polochic fault after the late Miocene. This shift is interpreted as a ``pull-up'' of North American blocks into the Caribbean realm. To the west, the PMFS interact with a trench-parallel fault zone that links the Tonala fault to the Jalpatagua fault. These faults bound a fore-arc sliver that is shared by the two overriding plates. We propose that the dextral Jalpatagua fault merges with the sinistral PMFS, leaving behind a suturing structure, the Tonala fault. This tectonic ``zipper'' allows the migration of the triple junction. As a result, the fore-arc sliver comes into contact with the North American plate and helps to maintain a linear subduction zone along the trailing edge of the Caribbean plate. All these processes currently make the triple junction increasingly diffuse as it propagates eastward and inland within both overriding plates.

Smoking and life expectancy among HIV-infected individuals on antiretroviral therapy in Europe and North America.

BACKGROUND: Cardiovascular disease and non-AIDS malignancies have become major causes of death among HIV-infected individuals. The relative impact of lifestyle and HIV-related factors are debated. METHODS: We estimated associations of smoking with mortality more than 1 year after antiretroviral therapy (ART) initiation among HIV-infected individuals enrolled in European and North American cohorts. IDUs were excluded. Causes of death were assigned using standardized procedures. We used abridged life tables to estimate life expectancies. Life-years lost to HIV were estimated by comparison with the French background population. RESULTS: Among 17 995 HIV-infected individuals followed for 79 760 person-years, the proportion of smokers was 60%. The mortality rate ratio (MRR) comparing smokers with nonsmokers was 1.94 [95% confidence interval (95% CI) 1.56-2.41]. The MRRs comparing current and previous smokers with never smokers were 1.70 (95% CI 1.23-2.34) and 0.92 (95% CI 0.64-1.34), respectively. Smokers had substantially higher mortality from cardiovascular disease, non-AIDS malignancies than nonsmokers [MRR 6.28 (95% CI 2.19-18.0) and 2.67 (95% CI 1.60-4.46), respectively]. Among 35-year-old HIV-infected men, the loss of life-years associated with smoking and HIV was 7.9 (95% CI 7.1-8.7) and 5.9 (95% CI 4.9-6.9), respectively. The life expectancy of virally suppressed, never-smokers was 43.5 years (95% CI 41.7-45.3), compared with 44.4 years among 35-year-old men in the background population. Excess MRRs/1000 person-years associated with smoking increased from 0.6 (95% CI -1.3 to 2.6) at age 35 to 43.6 (95% CI 37.9-49.3) at age at least 65 years. CONCLUSION: Well treated HIV-infected individuals may lose more life years through smoking than through HIV. Excess mortality associated with smoking increases markedly with age. Therefore, increases in smoking-related mortality can be expected as the treated HIV-infected population ages. Interventions for smoking cessation should be prioritized.

Un nuevo problema en espacios verdes urbanos: el pulgón Myzocallis (Lineomyzocallis) walshii (Hemiptera: Aphididae) y el roble americano (Quercus rubra)

Myzocallis (Lineomyzocallis) walshii (Monell) es un pulgón nativo del este de Nor- teamérica que se detectó por primera vez en España en 1995 y cuyo principal huésped es el roble americano (Quercus rubra L.). Los robles americanos se emplean como árbol ornamental en ambientes urbanos en diversas ciudades españolas, donde las proliferaciones del pulgón generan gran cantidad de melaza provocando daños estéticos y de confort. Durante 2008 y 2009 se efectuó el seguimiento de la fenología y de la densidad de población de M. walshii y de otros pulgones en robles americanos plantados en alineación en la ciudad de Girona y se estimaron los daños producidos. Asimismo se valoró la relación entre la abundancia de pulgones y los daños ocasionados. Finalmente se identificaron los principales grupos de enemigos naturales, a la vez que se cuantificó su abundancia. M. walshii fue la única especie de pulgón que afectó a los robles americanos. Este pulgón pasa el invierno en forma de huevo, las primeras ninfas surgen a la salida de hojas y las distintas generaciones de individuos partenogenéticos se mantienen a niveles variables hasta mediados de otoño, cuando aparecen las formas sexuales. Existe una correlación positiva entre la abundancia del pulgón y los daños de confort, incluso cuando la densidad es baja. Parasitoides y coccinélidos fueron los enemigos naturales más frecuentemente registrados, aunque su abundancia fue relativamente escasa. Se discute el papel de las condiciones climáticas y de los enemigos naturales en la determinación de la abundancia de M. walshii.