The role of parasites in the invasion success of the exotic brine shrimp Artemia Franciscana in the Meditarranean region

Trabajo presentado en el Symposium for European Freshwater Science, celebardo en Girona del 27 de junio al 1 de julio de 2011.Biological invasions are main threats to biodiversity at global scale and increasing numbers of studies suggest that parasites may have a role. However, the mechanism through which parasites may influence the outcome of the invasion is poorly understood. Here we provide evidence supporting the role of parasites as potential agents mediating the competitive exclusion of Mediterranean brine shrimps Artemia (A. parthenogenetica and A. salina) by the exotic American A. franciscana, using different native and invasive populations from South Spain and South France. Our results revealed high rates of infection by cestodes in native brine shrimps, sometimes with extreme prevalences of up to 100%. In contrast, A. franciscana populations showed very low diversity, prevalence and burden of cestodes. The effect of parasites in native populations was multiple, ranging from reproduction and survival, to life history traits, microhabitat selection and diet. Infection strongly reduced host fitness by both, reducing fecundity (parasite castration) and indirectly increasing predation by birds final hosts as revealed by prey choice experiments. We found evidence that high rate of parasitism (particularly the castrating parasite Flamingolepis liguloides, the most prevalent cestode in natives but nearly absent in the exotic Artemia), indirectly affected the life-history strategy of non infected individuals, inducing for example earlier maturation. Moreover cestodes influenced spatial (vertical and horizontal) distribution of the host, altering the diet as revealed by isotopic analysis. Contrasting with the strong impact of parasites in native populations, we have never observed any pathology (castration, behavioural alteration, etc) associated with infection in the exotic species. Overall, the results of this study suggest that the large impact of cestode on the native, but not the invading species, is likely to confer a decisive competitive advantage to the invader, contributing to explain the demographic success of A. franciscana in the Mediterranean region.Peer reviewe

Diverse values of nature for sustainability

Twenty-five years since foundational publications on valuing ecosystem services for human well-being(1,2), addressing the global biodiversity crisis(3) still implies confronting barriers to incorporating nature's diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever(4). Notwithstanding agreements to incorporate nature's values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)(5) and the UN Sustainable Development Goals(6), predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature(7). Arguably, a 'values crisis' underpins the intertwined crises of biodiversity loss and climate change(8), pandemic emergence(9) and socio-environmental injustices(10). On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature's diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions(7,11). Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures

Diverse values of nature for sustainability

Twenty-five years since foundational publications on valuing ecosystem services for human well-being1,2, addressing the global biodiversity crisis3 still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever4. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)5 and the UN Sustainable Development Goals6, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature7. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change8, pandemic emergence9 and socio-environmental injustices10. On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions7,11. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures

ϒ production in p–Pb collisions at √sNN=8.16 TeV

ϒ production in p–Pb interactions is studied at the centre-of-mass energy per nucleon–nucleon collision √sNN = 8.16 TeV with the ALICE detector at the CERN LHC. The measurement is performed reconstructing bottomonium resonances via their dimuon decay channel, in the centre-of-mass rapidity intervals 2.03 < ycms < 3.53 and −4.46 < ycms < −2.96, down to zero transverse momentum. In this work, results on the ϒ(1S) production cross section as a function of rapidity and transverse momentum are presented. The corresponding nuclear modification factor shows a suppression of the ϒ(1S) yields with respect to pp collisions, both at forward and backward rapidity. This suppression is stronger in the low transverse momentum region and shows no significant dependence on the centrality of the interactions. Furthermore, the ϒ(2S) nuclear modification factor is evaluated, suggesting a suppression similar to that of the ϒ(1S). A first measurement of the ϒ(3S) has also been performed. Finally, results are compared with previous ALICE measurements in p–Pb collisions at √sNN = 5.02 TeV and with theoretical calculations.publishedVersio

Diverse values of nature for sustainability

Twenty-five years since foundational publications on valuing ecosystem services for human well-being, addressing the global biodiversity crisis still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF) and the UN Sustainable Development Goals, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change, pandemic emergence and socio-environmental injustices. On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures

An examination of genetic variation and selection on condition in Drosophila melanogaster males

According to the genic capture hypothesis, the maintenance of additive genetic variation in fitness-related traits is due to both condition-dependence of these traits and high genetic variation for condition. Evidence supporting this latter assumption is scarce. In this study, we investigated, using hemiclonal analysis, standing genetic variation for condition and relative adult fitness in male Drosophila melanogaster (Meigen) (Diptera: Drosophilidae). The absolute fat and the relative fat content were used as indices of body condition and were measured along with adult relative fitness from males reared in high or low larval densities. The results did not demonstrate genetic variation for condition or adult relative fitness. However, the larval density encountered during development had a strong and significant effect on all traits. Surprisingly, although not significant, negative selection gradients acting on absolute fat and relative fat content were also found in both treatments. These findings challenge one of the main assumptions of the genic capture hypothesis and the use of fat content as an ideal index of condition

Air-borne genotype by genotype indirect genetic effects are substantial in the filamentous fungus Aspergillus nidulans

AGAP : équipe GE2popGenotype by genotype indirect genetic effects (G x G IGEs) occur when the phenotype of an individual is influenced by an interaction between its own genotype and those of neighbour individuals. Little is known regarding the relative importance of G x G IGEs compared with other forms of direct and indirect genetic effects. We quantified the relative importance of IGEs in the filamentous fungus Aspergillus nidulans, a species in which IGEs are likely to be important as air-borne social interactions are known to affect growth. We used a collection of distantly related wild isolates, lab strains and a set of closely related mutation accumulation lines to estimate the contribution of direct and indirect genetic effects on mycelium growth rate, a key fitness component. We found that indirect genetic effects were dominated by G x G IGEs that occurred primarily between a focal genotype and its immediate neighbour within a vertical stack, and these accounted for 11% of phenotypic variation. These results indicate that G x G IGEs may be substantial, at least in some systems, and that the evolutionary importance of these interactions may be underappreciated, especially in microbes. We advocate for a wider use of the IGE framework in both applied (for example, choice of varietal mixtures in plant breeding) and evolutionary genetics (kin selection/kin competition studies)

Population management using gene drive: molecular design, models of spread dynamics and assessment of ecological risks

International audienceCRISPR gene drive has recently been proposed as a promising technology for population management, including in conservation genetics. The technique would consist in releasing genetically engineered individuals that are designed to rapidly propagate a desired mutation or transgene into wild populations. Potential applications in conservation biology include the control of invasive pest populations that threaten biodiversity (eradication and suppression drives), or the introduction of beneficial mutations in endangered populations (rescue drives). The propagation of a gene drive is affected by different factors that depend on the drive construct (e.g. its fitness effect and timing of expression) or on the target species (e.g. its mating system and population structure). We review potential applications of the different types of gene drives for conservation. We examine the challenges posed by the evolution of resistance to gene drives and review the various molecular and environmental risks associated with gene drives (e.g. propagation to non target populations or species and unintended detrimental ecosystem impacts). We provide some guidelines for future gene drive research and discuss ethical, biosafety and regulation issue

Influence of Floods and Growth Duration on the Productivity of Wet Grasslands of Echinochloa stagnina (Retz) P. Beauv. in an East African Floodplain

International audienceEchinochloa stagnina (Retz) P. Beauv., a widespread semi-aquatic perennial grass, is a key species for the sustainability of many African wetlands. In an effort to assess interactions between hydrological regimes and management strategies targeting conservation, this study focuses on characterizing the growth of a typical East African wet grassland and describing the relative influence of floods and management practices on its growth rates. Naturally flooded grassland, subjected to a factorial design protocol with different levels of irrigation and cutting frequencies, was sampled during 15 months in the Tana River Delta, Kenya. Statistical analyses of the data, using linear mixed models accounting for temporal auto-correlation, were undertaken. Reduced cutting frequencies slightly increased growth rates, except under water-limited conditions. Increased water supply had a positive effect on growth rates, the latter noting a five- and ten-fold increase from water-limited to water non-limited to flooded conditions. Floods impacted grasslands by increasing growth rates, which attained very high values of 225 kgDM ha−1 day−1, extending growth period and limiting the negative effect of severe phytomass removal through clipping. These results support the view that rangeland and water management for the Tana River Delta, and more widely for tropical floodplain grasslands, should be jointly undertaken

Development time mediates the effect of larval diet on ageing and mating success of male antler flies in the wild

International audienceHigh-quality developmental environments often improve individual performance into adulthood, but allocating toward early-life traits, such as growth, development rate, and reproduction, may lead to trade-offs with late life performance. It is therefore uncertain how a rich developmental environment will affect the ageing process (senescence), particularly in wild insects. To investigate the effects of early-life environmental quality on insect life-history traits, including senescence, we reared larval antler flies (Protopiophila litigata) on four diets of varying nutrient concentration, then recorded survival and mating success of adult males released in the wild. Declining diet quality was associated with slower development, but had no effect on other life-history traits once development time was accounted for. Fast developing males were larger and lived longer, but experienced more rapid senescence in survival and lower average mating rate compared to slow developers. Ultimately, larval diet, development time, and body size did not predict lifetime mating success. Thus, a rich environmentled to a mixture of apparent benefits and costs, mediated by development time. Our results indicate that“silver spoon” effects can be complex and that development time mediates the response of adult life-history traits to early-life environmental quality