164 research outputs found

    Aster Models with Random Effects via Penalized Likelihood

    Get PDF
    1 online resource (PDF, 61 pages

    Natural variation and the capacity to adapt to ocean acidification in the keystone sea urchin Strongylocentrotus purpuratus

    Get PDF
    A rapidly growing body of literature documents the potential negative effects of CO2-driven ocean acidification (OA) on marine organisms. However, nearly all this work has focused on the effects of future conditions on modern populations, neglecting the role of adaptation. Rapid evolution can alter demographic responses to environmental change, ultimately affecting the likelihood of population persistence, but the capacity for adaptation will differ among populations and species. Here, we measure the capacity of the ecologically important purple sea urchin Strongylocentrotus purpuratus to adapt to OA, using a breeding experiment to estimate additive genetic variance for larval size (an important component of fitness) under future high-pCO2/low-pH conditions. Although larvae reared under future conditions were smaller than those reared under present-day conditions, we show that there is also abundant genetic variation for body size under elevated pCO2, indicating that this trait can evolve. The observed heritability of size was 0.40 ± 0.32 (95% CI) under low pCO2, and 0.50 ± 0.30 under high-pCO2 conditions. Accounting for the observed genetic variation in models of future larval size and demographic rates substantially alters projections of performance for this species in the future ocean. Importantly, our model shows that after incorporating the effects of adaptation, the OA-driven decrease in population growth rate is up to 50% smaller, than that predicted by the \u27no-adaptation\u27 scenario. Adults used in the experiment were collected from two sites on the coast of the Northeast Pacific that are characterized by different pH regimes, as measured by autonomous sensors. Comparing results between sites, we also found subtle differences in larval size under high-pCO2 rearing conditions, consistent with local adaptation to carbonate chemistry in the field. These results suggest that spatially varying selection may help to maintain genetic variation necessary for adaptation to future OA. © 2013 John Wiley & Sons Ltd

    Does country of origin affect brand associations? The case of Italian brands in China

    Get PDF
    none3noFindings related to how country of origin affects consumers’ product evaluations are still not consistent. Previous studies are mainly based on experiments and the results related to consumer judgements come from the elaboration of scores given to semantic scale items. Considering that brand image consists of a network of associations, the aim of this research is to evaluate how country of origin affects this entire network. An experiment was conducted involving 301 Chinese subjects to test the hypothesis that country stereotypes can be transferred to brands.noneFrancesca Checchinato, Marta Disegna, Tiziano VescoviChecchinato, Francesca; Disegna, Marta; Vescovi, Tizian

    Quantifying Rates of Evolutionary Adaptation in Response to Ocean Acidification

    Get PDF
    The global acidification of the earth's oceans is predicted to impact biodiversity via physiological effects impacting growth, survival, reproduction, and immunology, leading to changes in species abundances and global distributions. However, the degree to which these changes will play out critically depends on the evolutionary rate at which populations will respond to natural selection imposed by ocean acidification, which remains largely unquantified. Here we measure the potential for an evolutionary response to ocean acidification in larval development rate in two coastal invertebrates using a full-factorial breeding design. We show that the sea urchin species Strongylocentrotus franciscanus has vastly greater levels of phenotypic and genetic variation for larval size in future CO2 conditions compared to the mussel species Mytilus trossulus. Using these measures we demonstrate that S. franciscanus may have faster evolutionary responses within 50 years of the onset of predicted year-2100 CO2 conditions despite having lower population turnover rates. Our comparisons suggest that information on genetic variation, phenotypic variation, and key demographic parameters, may lend valuable insight into relative evolutionary potentials across a large number of species

    Climate Change and the Future of California's Endemic Flora

    Get PDF
    The flora of California, a global biodiversity hotspot, includes 2387 endemic plant taxa. With anticipated climate change, we project that up to 66% will experience >80% reductions in range size within a century. These results are comparable with other studies of fewer species or just samples of a region's endemics. Projected reductions depend on the magnitude of future emissions and on the ability of species to disperse from their current locations. California's varied terrain could cause species to move in very different directions, breaking up present-day floras. However, our projections also identify regions where species undergoing severe range reductions may persist. Protecting these potential future refugia and facilitating species dispersal will be essential to maintain biodiversity in the face of climate change

    Invasive Plants and Enemy Release: Evolution of Trait Means and Trait Correlations in Ulex europaeus

    Get PDF
    Several hypotheses that attempt to explain invasive processes are based on the fact that plants have been introduced without their natural enemies. Among them, the EICA (Evolution of Increased Competitive Ability) hypothesis is the most influential. It states that, due to enemy release, exotic plants evolve a shift in resource allocation from defence to reproduction or growth. In the native range of the invasive species Ulex europaeus, traits involved in reproduction and growth have been shown to be highly variable and genetically correlated. Thus, in order to explore the joint evolution of life history traits and susceptibility to seed predation in this species, we investigated changes in both trait means and trait correlations. To do so, we compared plants from native and invaded regions grown in a common garden. According to the expectations of the EICA hypothesis, we observed an increase in seedling height. However, there was little change in other trait means. By contrast, correlations exhibited a clear pattern: the correlations between life history traits and infestation rate by seed predators were always weaker in the invaded range than in the native range. In U. europaeus, the role of enemy release in shaping life history traits thus appeared to imply trait correlations rather than trait means. In the invaded regions studied, the correlations involving infestation rates and key life history traits such as flowering phenology, growth and pod density were reduced, enabling more independent evolution of these key traits and potentially facilitating local adaptation to a wide range of environments. These results led us to hypothesise that a relaxation of genetic correlations may be implied in the expansion of invasive species
    corecore