Optimal methods for fitting probability distributions to propagule retention time in studies of zoochorous dispersal

Background: Propagule retention time is a key factor in determining propagule dispersal distance and the shape of “seed shadows”. Propagules dispersed by animal vectors are either ingested and retained in the gut until defecation or attached externally to the body until detachment. Retention time is a continuous variable, but it is commonly measured at discrete time points, according to pre-established sampling time-intervals. Although parametric continuous distributions have been widely fitted to these interval-censored data, the performance of different fitting methods has not been evaluated. To investigate the performance of five different fitting methods, we fitted parametric probability distributions to typical discretized retention-time data with known distribution using as data-points either the lower, mid or upper bounds of sampling intervals, as well as the cumulative distribution of observed values (using either maximum likelihood or non-linear least squares for parameter estimation); then compared the estimated and original distributions to assess the accuracy of each method. We also assessed the robustness of these methods to variations in the sampling procedure (sample size and length of sampling time-intervals). Results: Fittings to the cumulative distribution performed better for all types of parametric distributions (lognormal, gamma and Weibull distributions) and were more robust to variations in sample size and sampling time-intervals. These estimated distributions had negligible deviations of up to 0.045 in cumulative probability of retention times (according to the Kolmogorov–Smirnov statistic) in relation to original distributions from which propagule retention time was simulated, supporting the overall accuracy of this fitting method. In contrast, fitting the sampling-interval bounds resulted in greater deviations that ranged from 0.058 to 0.273 in cumulative probability of retention times, which may introduce considerable biases in parameter estimates. Conclusions: We recommend the use of cumulative probability to fit parametric probability distributions to propagule retention time, specifically using maximum likelihood for parameter estimation. Furthermore, the experimental design for an optimal characterization of unimodal propagule retention time should contemplate at least 500 recovered propagules and sampling time-intervals not larger than the time peak of propagule retrieval, except in the tail of the distribution where broader sampling time-intervals may also produce accurate fitsPeer reviewe

A synthesis of Eurasian Curlew (Numenius arquata arquata) demography and population viability to inform its management

The European population of Eurasian Curlew Numenius arquata arquata, a nearthreatened wader subspecies, has undergone pronounced population declines over the past 30 years. To assess the demography and viability of its global population, we surveyed studies quantifying demographic rates (productivity and survival) and complemented this review with new estimates of survival probability at the flyway scale. Then, using a demographic model, we estimated population growth rates while accounting for the range of variation of demographic parameters, and compared these estimates (expected based on demographic rates) with those observed based on population censuses. Both observed and expected average growth rates were negative but the observed rates were higher than estimates from demographic models (λ = 0.98–0.99 compared with 0.85–0.95). This discrepancy implies that there is geographical variation in the demography of different populations that is not fully covered by current demographic data, namely unstudied regions with higher productivity. According to our calculations, at the flyway scale, productivity is currently c. 0.57 fledglings per pair per year, higher than the average reported productivity of 0.29, but lower than the 0.68 needed to achieve a stable global population size (λ = 1). Adult survival, estimated at 0.90, was the most sensitive parameter determining population growth rates, but the low productivity levels over the last few decades seems to be the most probable cause of population declines. The negative population growth rates require immediate conservation actions to preserve adult survival and increase the extremely low productivity in western and northern European populations to values above 0.68 fledglings per pair per year. We hope our synthesis on the demographic status of Curlew in Europe will encourage the collection of more demographic data and allow concrete management goals at the flyway scale to be established in order to recover the global population of this iconic species.Fédération Nationale des Chasseurs (Grant/Award Number: "FNC-PSN-PR11B-2013")

Trail cameras are a key monitoring tool for determining target and non-target bait-take during rodent removal operations: evidence from Desecheo Island rat eradication

Efforts to remove invasive rodents (e.g. Rattus spp. and Mus musculus) from islands often use toxicant-laced baits containing the anticoagulants brodifacoum or diphacinone. Rodenticide baits are generally delivered through aerialor hand-broadcast, or in bait stations. These baits are not rodent-specific and are subject to non-target consumption or secondary exposure (e.g. an individual preying upon another individual that has consumed bait). During rodenticide applications, it is generally unknown which animals are visiting and consuming bait; and to quantify this, we recommend using trail cameras (e.g. Reconyxtm motion-activated infra-red) positioned to monitor individual bait pellets. To demonstrate the importance and effectiveness of using trail cameras during such operations, we report results of target (Rattus rattus, black rat) and non-target (native land crab, lizard, insect) bait-interactions after an aerial-broadcast of (Rattus rattus, black rat) and non-target (native land crab, lizard, insect) bait-interactions after an aerial-broadcast of Brodifacoum-25D Conservation to eradicate rats from Desecheo Island, Puerto Rico. During the first five days following bait application, trail cameras (n = 15) revealed that there were 40 incidences of animals contacting bait pellets: 50% rat, 32% hermit crab, 13% Ameiva lizard, and 5% insect. Trail cameras provide temporal and spatial information regarding the eff ectiveness of rodent removal, and the last rat pictured by trail cameras on Desecheo was six days after bait application began. Trail cameras revealed 30 incidences of animals contacting bait pellets 6–20 days after bait application began: 47% hermit crab, 37% Ameiva lizard, 13% insect, and 3% black crab. Despite viewing ~69,000 images from trail cameras, lizards were never pictured consuming bait on Desecheo; therefore, any brodifacoum exposure to Desecheo lizards likely occurred via secondary pathways (e.g. consumption of contaminated insects). Scaling up, we estimate that \u3e 75% of the total bait distributed on Desecheo was not consumed by rats. Trail cameras help inform the hazards of rodenticide use and can be easily incorporated into rodent removal operations

Feeding Patterns of Potential West Nile Virus Vectors in South-West Spain

Background: Mosquito feeding behaviour determines the degree of vector–host contact and may have a serious impact on the risk of West Nile virus (WNV) epidemics. Feeding behaviour also interacts with other biotic and abiotic factors that affect virus amplification and transmission. Methodology/Principal Findings: We identified the origin of blood meals in five mosquito species from three different wetlands in SW Spain. All mosquito species analysed fed with different frequencies on birds, mammals and reptiles. Both ‘mosquito species’ and ‘locality’ explained a similar amount of variance in the occurrence of avian blood meals. However, ‘season of year’ was the main factor explaining the presence of human blood meals. The differences in diet resulted in a marked spatial heterogeneity in the estimated WNV transmission risk. Culex perexiguus, Cx. modestus and Cx. pipiens were the main mosquito species involved in WNV enzootic circulation since they feed mainly on birds, were abundant in a number of localities and had high vector competence. Cx. perexiguus may also be important for WNV transmission to horses, as are Cx. pipiens and Cx. theileri in transmission to humans. Estimates of the WNV transmission risk based on mosquito diet, abundance and vector competence matched the results of previous WNV monitoring programs in the area. Our sensitivity analyses suggested that mosquito diet, followed by mosquito abundance and vector competence, are all relevant factors in understanding virus amplification and transmission risk in the studied wild ecosystems. At some of the studied localities, the risk of enzootic circulation of WNV was relatively high, even if the risk of transmission to humans and horses was less. Conclusions/Significance: Our results describe for first time the role of five WNV candidate vectors in SW Spain. Interspecific and local differences in mosquito diet composition has an important effect on the potential transmission risk of WNV to birds, horses and humansPeer reviewe

The challenge of west nile virus in Europe: Knowledge gaps and research priorities

West Nile virus (WNV) is continuously spreading across Europe, and other continents, i.e. North and South America and many other regions of the world. Despite the overall sporadic nature of outbreaks with cases of West Nile neuroinvasive disease (WNND) in Europe, the spillover events have increased and the virus has been introduced into new areas. The high genetic diversity of the virus, with remarkable phenotypic variation, and its endemic circulation in several countries, require an intensification of the integrated and multidisciplinary research efforts built under the 7th Framework Programme of the European Union (FP7). It is important to better clarify several aspects of WNV circulation in Europe, including its ecology, genomic diversity, pathogenicity, transmissibility, diagnosis and control options, under different environmental and socio-economic scenarios. Identifying WNV endemic as well as infection-free areas is becoming a need for the development of human vaccines and therapeutics and the application of blood and organs safety regulations. This review, produced as a joint initiative among European experts and based on analysis of 118 scientific papers published between 2004 and 2014, provides the state of knowledge on WNV and highlights the existing knowledge and research gaps that need to be addressed with high priority in Europe and neighbouring countries

Regional Genetic Structure in the Aquatic Macrophyte Ruppia cirrhosa Suggests Dispersal by Waterbirds

The evolutionary history of the genus Ruppia has been shaped by hybridization, polyploidisation and vicariance that have resulted in a problematic taxonomy. Recent studies provided insight into species circumscription, organelle takeover by hybridization, and revealed the importance of verifying species identification to avoid distorting effects of mixing different species, when estimating population connectivity. In the present study, we use microsatellite markers to determine population diversity and connectivity patterns in Ruppia cirrhosa including two spatial scales: (1) from the Atlantic Iberian coastline in Portugal to the Siculo-Tunisian Strait in Sicily and (2) within the Iberian Peninsula comprising the Atlantic-Mediterranean transition. The higher diversity in the Mediterranean Sea suggests that populations have had longer persistence there, suggesting a possible origin and/or refugial area for the species. The high genotypic diversities highlight the importance of sexual reproduction for survival and maintenance of populations. Results revealed a regional population structure matching a continent-island model, with strong genetic isolation and low gene flow between populations. This population structure could be maintained by waterbirds, acting as occasional dispersal vectors. This information elucidates ecological strategies of brackish plant species in coastal lagoons, suggesting mechanisms used by this species to colonize new isolated habitats and dominate brackish aquatic macrophyte systems, yet maintaining strong genetic structure suggestive of very low dispersal.Fundacao para a Cincia e Tecnologia (FCT, Portugal) [PTDC/MAR/119363/2010, BIODIVERSA/0004/2015, UID/Multi/04326/2013]Pew FoundationSENECA FoundationMurcia Government, Spain [11881/PI/09]FCT Investigator Programme-Career Development [IF/00998/2014]Spanish Ministry of Education [AP2008-01209]European Community [00399/2012]info:eu-repo/semantics/publishedVersio

Thienopyrimidine Derivatives as GPR55 Receptor Antagonists: Insight into Structure-Activity Relationship

GPR55 is an orphan G-protein coupled receptor involved in various pathophysiological conditions. However, there are only a few noncannabinoid GPR55 ligands reported so far. The lack of potent and selective GPR55 ligands precludes a deep exploration of this receptor. The studies presented here focused on a thienopyrimidine scaffold based on the GPR55 antagonist ML192, previously discovered by high-throughput screening. The GPR55 activities of the new synthesized compounds were assessed using β-arrestin recruitment assays in Chinese hamster ovary cells overexpressing human GPR55. Some derivatives were identified as GPR55 antagonists with functional efficacy and selectivity versus CB1 and CB2 cannabinoid receptors.M.E.A., P.H.R., and N.J. are supported by National Institutes of Health grant R01 DA0455698. M.E.A. and P.Z. thank the financial support NIH P30 DA013429. P.M. and N.J. are supported by the Ministry of Science, Innovation, and Universities, Spain (MCIU)/FEDER grant RTI2018-095544-B-I00 and the Spanish National Research Council (CSIC) grant PIE-201580E033. P.M. acknowledges the Comunidad de Madrid (CM) programme “Atraccion de Talento” number 2018-T2/BMD-10819 and “Juan de la Cierva Incorporación Programme-MICIU” (IJC 2019-042182-I

Responses of Southern Ocean seafloor habitats and communities to global and local drivers of change

Knowledge of life on the Southern Ocean seafloor has substantially grown since the beginning of this century with increasing ship-based surveys and regular monitoring sites, new technologies and greatly enhanced data sharing. However, seafloor habitats and their communities exhibit high spatial variability and heterogeneity that challenges the way in which we assess the state of the Southern Ocean benthos on larger scales. The Antarctic shelf is rich in diversity compared with deeper water areas, important for storing carbon (“blue carbon”) and provides habitat for commercial fish species. In this paper, we focus on the seafloor habitats of the Antarctic shelf, which are vulnerable to drivers of change including increasing ocean temperatures, iceberg scour, sea ice melt, ocean acidification, fishing pressures, pollution and non-indigenous species. Some of the most vulnerable areas include the West Antarctic Peninsula, which is experiencing rapid regional warming and increased iceberg-scouring, subantarctic islands and tourist destinations where human activities and environmental conditions increase the potential for the establishment of non-indigenous species and active fishing areas around South Georgia, Heard and MacDonald Islands. Vulnerable species include those in areas of regional warming with low thermal tolerance, calcifying species susceptible to increasing ocean acidity as well as slow-growing habitat-forming species that can be damaged by fishing gears e.g., sponges, bryozoan, and coral species. Management regimes can protect seafloor habitats and key species from fishing activities; some areas will need more protection than others, accounting for specific traits that make species vulnerable, slow growing and long-lived species, restricted locations with optimum physiological conditions and available food, and restricted distributions of rare species. Ecosystem-based management practices and long-term, highly protected areas may be the most effective tools in the preservation of vulnerable seafloor habitats. Here, we focus on outlining seafloor responses to drivers of change observed to date and projections for the future. We discuss the need for action to preserve seafloor habitats under climate change, fishing pressures and other anthropogenic impacts