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19,493 results for “Populism”
Sources of coaster brook trout (Salvelinus fontinalis) revealed by genomic analysis of brook trout populations along Minnesota's shoreline with Lake Superior
<p>Knowledge of population-level relationships and how these relationships pertain to different life history forms is critical to developing effective management plans for native trout, char, and salmon. In the Lake Superior basin, identifying effective restoration strategies for coaster brook trout (<em>Salvelinus</em> <em>fontinalis</em>), a lake-inhabiting form of brook trout, is hampered by limited information on genetic connectivity and source-sink dynamics among brook trout populations. Here, we infer these relationships by surveying 8,178 single nucleotide polymorphisms in 234 brook trout from seven rivers along the Minnesota shoreline with Lake Superior, including from reaches above and below natural waterfalls that prevent upstream movement. We identified well-differentiated above-barrier populations that supply brook trout to below-barrier reaches. We also compared within-river brook trout to 26 coaster brook trout from Lake Superior. We identified at least four source populations for these coaster brook trout, three of which were located within rivers. Additionally, we estimated N<sub>E</sub> for within-river populations and detected a decline across recent generations, with the most recent estimates approaching critical thresholds. Finally, comparisons with 94 domestic brook trout representing nine hatchery strains revealed a lack of domestic introgression into wild populations, demonstrating the importance of natural reproduction to population persistence. Our results offer novel insights into sources of coaster brook trout and highlight the role of within-river populations in supporting the coaster life history. Management efforts focused on instream restoration may be more important to rehabilitating coaster brook trout than previously thought, and are urgently needed given the population-level conservation status reported here.</p>
Rice phenotypic data – CNA6 population and advanced lines
<p>One of the main challenges of breeding programs is to identify superior genotypes from a large number of candidates. By gradually increasing the frequency of favorable alleles in the breeding population, recurrent selection improves the population mean for target traits, increasing the chance to identify promising genotypes. In rice, population improvement through recurrent selection has been used very little to date, except in Latin America. At Embrapa (Brazilian Agricultural Research Corporation), the upland rice breeding program is conducted in two phases: population improvement followed by product development. In this study, the CNA6 population, evaluated over five cycles (3 to 7) of selection, including 20 field trials, was used to assess the realized genetic gain. A high rate of genetic gain was observed for grain yield, at 215 kg.ha<sup>-1</sup> per cycle or 67.8 kg.ha<sup>-1</sup> per year (3.08%). The CNA6 population outperformed the controls only for the last cycle, with a yield difference of 1,128 kg.ha<sup>-1</sup>. An analysis of the product development pipeline, based on 29 advanced yield trials with lines derived from cycles 3 to 6, showed that lines derived from the CNA6 population had high grain yield, but did not outperform the controls. These results demonstrate that the application of recurrent selection to a breeding population with sufficient genetic variability can result in significant genetic gains for quantitative traits, such as grain yield. The integration of this strategy into a two-phase breeding program also makes it possible to increase quantitative traits while selecting for other traits of interest.</p>
Data for: Population structure of a grassland songbird (Dolichonyx oryzivorus) to inform conservation units
<p>Understanding the patterns and processes driving population structure is crucial for conservation planning. Spatial conservation units (CUs) for one or more species have been defined using similarities in communities, habitats, and resource management concerns. Additionally, CU boundaries can be informed by population genetic structure. Here, we determined the population structure of the Bobolink (<em>Dolichonyx</em> <em>oryzivorus</em>), a migratory grassland bird. Its breeding range spans longitudinally across most of North America in the northern U.S. and southern Canada, and its population has declined by 59% from 1971 to 2014. We sampled blood from Bobolinks at seven breeding sites and used a ddRAD sequencing approach to identify 3236 SNPs for population genetic analyses. Using the Bayesian clustering approach, STRUCTURE, we found low levels of genetic differentiation across the breeding range. F st values ranged from 0.002 to 0.036 among all population pairs, and genetic structure followed an isolation-by-distance model. Despite low levels of genetic differentiation, we found evidence for four genetic groupings— breeding populations in Oregon and British Columbia were distinct from each other as well as from Central and eastern North American breeding populations. Investigating the demographic history of the populations using approximate Bayesian computation, we found evidence that western Bobolink populations are not relict populations but instead were founded during a recent westward range expansion, possibly enabled by agricultural expansion. We identify four genetics-based CUs that may serve as a complementary spatial framework, broader in scale compared to the commonly-used Bird Conservation Regions, for defining and achieving population objectives.</p>
Data for: Surrounding landscape, habitat and hybridization dynamics drive population structure and genetic diversity in the Saltmarsh Sparrow (Ammospiza caudacuta)
<p class="MsoNormal">Determining factors that shape a species' population genetic structure is beneficial for identifying effective conservation practices. We assessed population structure and genetic diversity for Saltmarsh Sparrow (<em>Ammospiza caudacuta</em>), an imperiled tidal marsh specialist, using 13 microsatellite markers and 964 individuals sampled from 24 marshes across the breeding range. We show that Saltmarsh Sparrow populations are structured regionally by isolation-by-distance, with gene flow occurring among marshes within ~110-135 km of one another. Isolation-by-resistance and isolation-by-environment also shape genetic variation; several habitat and landscape features are associated with genetic diversity and genetic divergence among populations. Human development in the surrounding landscape isolates breeding marshes, reducing genetic diversity and increasing population genetic divergence, while surrounding marshland and patch habitat quality (proportion high marsh and sea-level-rise trend) have the opposite effect. The distance of the breeding marsh to the Atlantic Ocean also influences genetic variation, with marshes farther inland being more divergent than coastal marshes. In northern marshes, hybridization with Nelson's Sparrow (<em>A. nelsoni</em>) strongly influences Saltmarsh Sparrow genetic variation, by increasing genetic diversity in the population; this has a concomitant effect of increasing genetic differentiation of marshes with high levels of introgression. From a conservation perspective, we found that the majority of population clusters have low effective population sizes, suggesting a lack of resiliency. To conserve the representative breadth of genetic and ecological diversity and to ensure redundancy of populations, it will be important to protect a diversity of marsh types across the latitudinal gradient of the species range, including multiple inland, coastal and urban populations, which we have shown to exhibit signals of genetic differentiation. It will also require maintaining connectivity at a regional level, by promoting high marsh habitat at the scale of gene flow (~130 km), while also ensuring "stepping stone" populations across the range. </p>
Morphological variability decreases in populations living in less suitable environments and close to the range edges
<p><strong>Aim:</strong> Geographic range expansion depends on ecological and evolutionary processes that may hamper local adaptations in populations living at range edges by constraining phenotypic variability. This study investigates the spatial patterns of the intraspecific variability of skull traits throughout the geographic range of a marsupial from the Brazilian Atlantic Forest. We aimed to answer whether the distance from the range edge and the environmental suitability explain the geographic variation of morphological variability of the species.</p> <p><strong>Location:</strong> Atlantic Forest, Brazil.</p> <p><strong>Taxon:</strong> <em>Marmosops incanus</em> (Didelphimorphia, Didelphidae).</p> <p><strong>Methods:</strong> We analysed adult specimens deposited in the main biological collections in southeastern Brazil. The morphological variability extent and integration within populations were characterised by 13 linear measures of the skull, using a multivariate approach. Environmental suitability for the species' occurrence was estimated by Ecological Niche Models, using climatic and vegetation productivity as predictors and three different modelling methods. Distance from the range edge was calculated based on the minimum linear distance between populations and the closest range limit. We fitted linear regressions and selected the best models that explained the spatial variation of morphological variability based on the Akaike information criterion.</p> <p><strong>Results:</strong> The extent of morphological variability of <em>M. incanus</em> is positively correlated with morphological integration and increases with local environmental suitability and distance from the range edges. However, the relationship between morphological variability and environmental suitability depends on the niche modelling method.</p> <p><strong>Main conclusions: </strong>Unfavourable environmental conditions constrain morphological variability within populations of the Gray slender opossum and may hamper local adaptation in peripheral populations living in less suitable environments. In addition to environmental conditions, geographic location of populations also plays an important role in phenotypic variability among populations. We stress the boundary effect of the species range on the local adaptation of peripheral populations and its possible consequences for the range expansion dynamics.</p>
Low genetic diversity and shallow population structure in the broom hare, Lepus castroviejoi (Lagomorpha:Leporidae)
<p><span class="TextRun SCXW115721130 BCX4"><span class="NormalTextRun SCXW115721130 BCX4">Microsatellite dataset of 322 hare samples from five species: 76 samples from the broom hare (</span></span><em><span class="TextRun SCXW115721130 BCX4"><span class="NormalTextRun SCXW115721130 BCX4">Lepus </span><span class="NormalTextRun SCXW115721130 BCX4">castroviejoi</span></span></em><span class="TextRun SCXW115721130 BCX4"><span class="NormalTextRun SCXW115721130 BCX4">); 81 for the European hare (<em>L. europaeus</em>); 68 for the Iberian hare (<em>L. granatensis</em>); 77 for the mountain hare (<em>L. timidus</em>); and 20 for the Italian hare (<em>L. corsicanus</em>).</span></span></p>
Data from: Mother knows best: Nest-site choice homogenizes embryo thermal environments among populations in a widespread ectotherm
<p><span>Species with large geographic ranges provide an excellent model of how different populations respond to dissimilar local conditions, particularly variation in climate. Maternal effects, such as oviposition-site choice greatly affect offspring phenotypes and survival. Thus, maternal behavior has the potential to mitigate the effects of divergent climatic conditions across a species' range. We delineated natural nesting areas of six populations of painted turtles (<em>Chrysemys picta</em>) that span a broad latitudinal range and quantified spatial and temporal variation in nest characteristics. To quantify microhabitats available for females to choose, we also identified sites within the nesting area of each location that were representative of available thermal microhabitats. Across the range females nested non-randomly and targeted microhabitats that generally had less canopy cover and thus higher nest temperatures. Nest microhabitats differed among locations but did not predictably vary with latitude or historic mean air temperature during embryonic development. In conjunction with other studies of these populations, nest-site choice appears to be homogenizing nest environments, buffering embryos from thermally-induced selection, which could stymie evolution of embryonic traits. Thus, although effective at a macroclimatic scale, nest-site choice may be unable to compensate for novel stressors that rapidly increase local temperatures.</span></p>
Investigating the Lower Mass Gap with Low Mass X-ray Binary Population Synthesis
<p>Title: Investigating the Lower Mass Gap with Low Mass X-ray Binary Population Synthesis </p> <p>Authors: Jared C. Siegel, Ilia Kiato, Vicky Kalogera, Christopher P. L. Berry,<br> Thomas J. Maccarone, Katelyn Breivik, Jeff J. Andrews, Simone S. Bavera,<br> Aaron Dotter, Tassos Fragos, Konstantinos Kovlakas, Devina Misra,<br> Kyle A. Rocha, Philipp M. Srivastava, Meng Sun, Zepei Xing,<br> and Emmanouil Zapartas<br> <br> Table: Summary of Population Synthesis Models</p> <p>Columns:<br> Population parameters:<br> CE: efficiency of common envelope unbinding, either:<br> * 1 or 5<br> CE merge: stars without a distinct core-envelope boundary that instigate a CE <br> event are either assumed to survive the CE (Optimistic) or are <br> assumed to merge (Pessimistic).<br> QMIN: minimum ZAMS ratio, either:<br> * 0.01<br> * Lifetime limited (pre-main-sequence lifetime of the secondary is shorter<br> than the main-sequence lifetime of the primary)<br> BRK: prescription for magnetic braking of a tidally coupled magnetic wind, either:<br> * H02: Hurley et al. 2002<br> * IT03: Ivanova & Taam 2003<br> ACC: amount of mass accreted during Roche-lobe overflow, either:<br> * 50% efficiency<br> * State dependent: (i) limited to ten-times the thermal rate if the accretor is a main-sequence, <br> Hertzsprung gap or core helium burning star, or (ii) unlimited if the accretor is a giant branch, <br> early asymptotic giant branch or asymptotic giant branch star. <br> Compact objects also experience conservative mass transfer, provided the <br> mass-transfer rate is sub-Eddington.<br> <br> Selection effect parameters:<br> weighting: logs what selection effects were considered for the detection weighted results, either:<br> *prob_occ: the probability that an outburst occurs and turns off during the survey<br> *prob_see: the probability that the outburst is bright enough to be detected<br> *prob: the product of prob_occ and prob_see<br> <br> RIA_nu: determines when the transition to radiatively inefficient accretion occurs, either:<br> *0 (no transition) or 0.05<br> <br> Results:<br> f_gap_N: fraction of LMXB systems with a mass gap BH (M<4.5Msol)<br> f_AIC_N: fraction of LMXB systems where the BH formed through accretion induced collapse of a NS<br> f_AIC_gap_N: fraction of LMXB systems where the BH formed through accretion induced collapse of a NS and<br> the BH is in the mass gap<br> fw_X_N: detection weighted fraction of X (e.g., gap, AIC, AIC_gap)<br> <br> Notes:<br> Each quantity is calculated for 5000 snapshots of the evolution tracks. <br> Here we report the Nth percentiles (e.g., 16, 50, 84) of each quantity.</p>
Data from: Remotely sensed environmental measurements detect decoupled processes driving population dynamics at contrasting scales
<p class="MsoNormal">The increasing availability of satellite imagery has supported a rapid expansion in forward-looking studies seeking to track and predict how climate change will influence wild population dynamics. However, these data can also be used in retrospect to provide additional context for historical data in the absence of contemporaneous environmental measurements. We used 167 Landsat-5 Thematic Mapper (TM) images spanning 13 years to identify environmental drivers of fitness and population size in a well-characterized population of banner-tailed kangaroo rats (<em>Dipodomys spectabilis</em>) in the southwestern United States. We found evidence of two decoupled processes that may be driving population dynamics in opposing directions over distinct time frames. Specifically, increasing mean surface temperature corresponded to increased individual fitness, where fitness is defined as the number of offspring produced by a single individual. This result contrasts with our findings for population size, where increasing surface temperature led to decreased numbers of active mounds. These relationships between surface temperature and (i) individual fitness and (ii) population size would not have been identified in the absence of remotely sensed data, indicating that such information can be used to test existing hypotheses and generate new ecological predictions regarding fitness at multiple spatial scales and degrees of sampling effort. To our knowledge, this study is the first to directly link remotely sensed environmental data to individual fitness in a nearly exhaustively sampled population, opening a new avenue for incorporating remote sensing data into eco-evolutionary studies.</p>
Data from: Multi-locus genomic signatures of local adaptation to snow across the landscape in California populations of a willow leaf beetle
<p>Organisms living in mountains contend with extreme climatic conditions, including short growing seasons and long winters with extensive snow cover. Anthropogenic climate change is driving unprecedented, rapid warming of montane regions across the globe, resulting in reduced winter snowpack. Loss of snow as a thermal buffer may have serious consequences for animals overwintering in soil, yet little is known about how variability in snowpack acts as a selective agent in montane ecosystems. Here we examine genomic variation in California populations of the leaf beetle <em>Chrysomela aeneicollis</em>, an emerging natural model system for understanding how organisms respond to climate change. We used a genotype-environment association approach to identify genomic signatures of local adaptation to microclimate in populations from three montane regions with variable snowpack and a coastal region with no snow. We found that both winter-associated environmental variation and geographic distance contribute to overall genomic variation across the landscape. We identified non-synonymous variation in novel candidate loci associated with cytoskeletal function, ion transport and membrane stability, cellular processes associated with cold tolerance in other insects. These findings provide intriguing evidence that variation in snowpack imposes selective gradients in montane ecosystems.</p>
Data from: Populating a continent: Phylogenomics reveal the timing of Australian frog diversification
<p><span>The Australian continent's size and isolation make it an ideal place for studying the accumulation and evolution of biodiversity. Long separated from the ancient supercontinent Gondwana, most of Australia's plants and animals are unique and endemic, including the continent's frogs. Australian frogs comprise a remarkable ecological and morphological diversity categorized into a small number of distantly related radiations. We present a phylogenomic hypothesis based on an exon-capture dataset that spans the main clades of Australian myobatrachoid, pelodryadid hyloid, and microhylid frogs. Our time-calibrated phylogenomic-scale phylogeny identifies great disparity in the relative ages of these groups which vary from Gondwanan relics to recent immigrants from Asia and include arguably the continent's oldest living vertebrate radiation. This age stratification provides insight into the colonization of</span><span></span><span>, </span><span>and diversification on, the Australian continent through deep time, during periods of dramatic climatic and community changes. Contemporary Australian frog diversity highlights the adaptive capacity of anurans, particularly in response to heat and aridity, and explains why they are one of the continent's most visible faunas.</span></p>
Germination of range-wide Quercus suber L. populations
<p>This database contains the individual germination times and rates of cork oak acorns under controlled conditions. Acorns were collected in 2021 from 9 natural populations comprising 10 mother trees per population in France, Italy, Portugal and Spain. The acorns were weighed per mother tree before being sown under controlled conditions at 15, 20 and 25°C. The final size of this database is 718 individual entries which include seed mass, germination rates and timing, and the emergence of the first leaf. The populations from which the acorns were collected are geo-referenced and the mother trees are identified by their circumference and dbh.</p>
Population genomic analysis of an emerging pathogen Lonsdalea quercina affecting various species of oaks in western North America
<p>Previously unrecognized diseases continue to threaten the health of forest ecosystems globally. Understanding processes leading to disease emergence is important for effective disease management and prevention of future epidemics. Utilizing whole genome sequencing, we studied the phylogenetic relationship and within diversity of two populations of the bacterial oak pathogen <em>Lonsdalea</em> <em>quercina</em> from western North America (Colorado and California) and compared these populations to other <em>Lonsdalea</em> species found worldwide. Phylogenetic analysis separated Colorado and California populations into two well-supported clades within the genus <em>Lonsdalea</em>, with an average nucleotide identity between them near species boundaries (95.31%) for bacteria, suggesting long isolation. Populations comprise distinct patterns in genetic structure and distribution. Genotypes collected from different host species and habitats were randomly distributed within the California cluster, while most Colorado isolates from introduced planted trees were distinct from isolates collected from a natural stand of CO native <em>Q. gambelii,</em> indicating the presence of cryptic population structure. The distribution of clones in California varied, while Colorado clones were always collected from neighboring trees. Despite its recent emergence, the Colorado population had higher nucleotide diversity, possibly due to migrants moving with nursery stock. Overall results suggest independent pathogen emergence in two states likely driven by changes in host-microbe interactions due to ecosystem conditions changing. To our knowledge, this is the first study on <em>L. quercina</em> population structure. Further studies are warranted to understand evolutionary relationships among <em>L. quercina</em> populations from different areas, including the native habitat of red oak in northeastern USA.</p>
Data from: The costs of living on the coast: reduction in body size and size-specific reproductive output in coastal populations of a widespread amphibian
<ol> <li>Body size is a critical component of organismal biology. Body size is known to be influenced by a plethora of environmental conditions, among which exposure to large-scale variations of salinity has been comparatively overlooked. Yet, exposure to salinity is known to affect energetic allocation toward growth and reproduction.</li> <li>In this study, we investigated the morphological differences between inland and coastal individuals of spined toads (<em>Bufo</em> <em>spinosus</em>) in Western France. </li> <li>We measured adult morphology both outside and during the reproductive season on 190 individuals, and assessed reproduction in pairs originating from inland (N=20) and coastal (N=30) environments.</li> <li>Overall, we found that adult coastal toads were smaller and lighter than inland individuals. Reproductive correlates of these differences included lower fecundity and smaller egg size (but higher egg density) in coastal females. Interestingly, these differences were not allometric correlates of body size, as coastal females invested proportionally less in all components of reproduction (fecundity, egg size and egg protection).</li> <li>These results suggest altered resource allocation to growth and reproduction in coastal amphibians, which may be related to the marked spatial gradient of salinity (measured in reproductive ponds) and the associated costs of osmoregulation (higher osmolality in coastal individuals), for which local adaptation and higher tolerance to salinity remains to be tested.</li> </ol>
Data for: Responses to saltwater exposure vary across species, populations, and life-stages in anuran amphibians
<p><span>To predict the impacts of environmental change on species, we must first understand the factors that limit the present-day ranges of species. Most anuran amphibians cannot survive at elevated salinities, which may drive their distribution in coastal locations. Previous research showed that coastal <em>Hyla cinerea</em> are locally adapted to brackish habitats in North Carolina (USA). Although <em>Hyla squirella</em> and <em>Hyla chrysoscelis </em>both inhabit coastal wetlands nearby, they have not been observed in saline habitats. We take advantage of naturally occurring microgeographic variation in coastal wetland occupancy exhibited by these congeneric treefrog species to explore how salt exposure affects oviposition site choice, hatching success, early tadpole survival, plasma osmolality, and tadpole body condition across coastal and inland locations. We observed higher survival among coastal</span><span> <em>H. cinerea</em> tadpoles than inland <em>H. cinerea</em>, which corroborates previous findings. But contrary to expectations, coastal <em>H. cinerea</em> had lower survival than <em>H. squirella</em> and <em>H. chrysoscelis</em>, indicating that all three species may be able to persist in saline wetlands. We also observed differences in tadpole plasma osmolality across species, locations, and salinities, but these differences were not associated with survival rates in saltwater. Instead, coastal occupancy may be affected by stage-specific processes like higher probability of total clutch loss as shown by inland <em>H. chrysoscelis</em> or maladaptive egg deposition patterns as shown by inland <em>H. squirella</em>. </span><span>Although we expected saltwater to be the primary filter driving species distributions along a coastal salinity gradient, it is likely that the factors dictating anuran ranges along the coast involve stage-, species-, and location specific processes that are mediated by ecological processes and life history traits.</span></p>
Sample extraction and SNP sequencing data for: Identification of sex-linked SNP markers in wild populations of monomorphic birds
<p><span>Single-nucleotide polymorphism (SNP) analyses are a powerful tool for population genetics, pedigree reconstruction and phenotypic trait mapping. However, the untapped potential of SNP markers to discriminate the sex of individuals in species with reduced sexual dimorphism or of individuals during immature stages remains a largely unexplored avenue. Here, we develop a novel protocol for molecular sexing of birds based on the detection of unique Z- and W-linked SNP markers. Our method is based on the identification of two unique loci, one in each sexual chromosome. Individuals are considered males when they show no calls for the W-linked SNP and are heterozygotic or homozygotic for the Z-linked SNP, while females show both Z- and W-linked SNP calls. We validated the method in the Jackdaw (<em>Corvus</em> <em>monedula</em>). The reduced sexual dimorphism in this species makes it difficult to sex individuals in the wild. We assessed the reliability of the method using 36 individuals of known sex and found that their sex was correctly assigned in 100% of cases. The sex-linked markers also proved to be widely applicable to discriminate males and females from a sample of 927 genotyped individuals of different maturity stages with an accuracy of 99.5%. Given that SNP markers are increasingly used in quantitative genetic analyses of wild populations, the approach we propose has a great potential to be integrated into broader genetic research programmes without the need for additional sexing techniques.</span></p>
Dataset for density estimation for an island population of raccoon dogs in Japan
<p><span>Estimation of the population</span><span> size</span><span> is essential for understanding population dynamics</span><span>. Estimating animal density using multiple methods and/or multiple attempts is required for accurate estimations. Raccoon dog (<em>Nyctereutes</em> <em>procyonoides</em>) is native to East Asia, including Japan, and has become an invasive species in Europe. Information on raccoon dog density in their native range is important to understand their invasion; however, relatively few studies have been conducted on raccoon dog density in their native range. In this study, we extracted DNA from fecal samples of raccoon dogs inhabiting a small island in Japan and conducted density estimation over two periods using DNA capture-recapture methods: CAPWIRE and SECR. We also investigated sex ratio</span> <span>using genetic sex identification. Density estimates using SECR were approximately threefold different between the two study periods: </span><span>17.2</span><span> individuals per km<sup>2</sup> in 2018 and </span><span>49.0 </span><span>individuals per km<sup>2</sup> in 2020. In contrast, estimates using CAPWIRE were relatively stable: </span><span>21.7</span><span> individuals per km<sup>2</sup> in 2018 and </span><span>24.3</span><span> individuals per km<sup>2</sup> in 2020. A drastic increase or decrease is not expected during the study period, and thus</span><span>, density estimates using CAPWIRE are more reasonable than </span><span>those using SECR. The small number of samples per individual might result in low accuracy of density estimates by SECR. The density estimated by CAPWIRE was similar to that in the main island in Japan</span> <span>and higher than that in Europe. Feeding competition with other omnivorous carnivores and/or predation risk by wolves might maintain the low density in Europe. The sex ratio of raccoon dogs was 1:1, which was similar to </span><span>the values in invasive raccoon dogs and </span><span>other canids. Further genetic census</span><span>, including sex identification in various landscapes in their native and invasive range, will enable us to understand not only the ecology of raccoon dogs but also their adaptations to </span><span>their invading areas.</span></p>
Variation among strains of Borrelia burgdorferi in host tissue abundance and lifetime transmission determine the population strain structure in nature
<p class="MsoNormal">Pathogen life history theory assumes a positive relationship between pathogen load in host tissues and pathogen transmission. Empirical evidence for this relationship is surprisingly rare due to the difficulty of measuring transmission for many pathogens. The comparative method, where a common host is experimentally infected with a set of pathogen strains, is a powerful approach for investigating the relationships between pathogen load and transmission. The validity of such experimental estimates of strain-specific transmission is greatly enhanced if they can predict the pathogen population strain structure in nature.</p> <p class="MsoNormal"><em>Borrelia burgdorferi</em> is a multi-strain, tick-borne spirochete that causes Lyme disease in North America. This study used 11 field-collected strains of <em>B. burgdorferi</em>, a rodent host (<em>Mus musculus, </em>C3H/HeJ) and its tick vector (<em>Ixodes scapularis</em>) to determine the relationship between pathogen load in host tissues and lifetime host-to-tick transmission (HTT). Mice were experimentally infected via tick bite with 1 of 11 strains. Lifetime HTT was measured by infesting mice with <em>I. scapularis </em>larval ticks on 3 separate occasions. The prevalence and abundance of the strains in the mouse tissues and the ticks were determined by qPCR. We used published databases to obtain estimates of the frequencies of these strains in wild <em>I. scapularis</em> populations.</p> <p>Spirochete loads in ticks and lifetime HTT varied significantly among the 11 strains of <em>B. burgdorferi</em>. Strains with higher spirochete loads in the host tissues were more likely to infect feeding larvae, which molted into nymphs with a higher probability of <em>B. burgdorferi</em> infection (<em>i.e.</em>, higher HTT). Our laboratory-based estimates of lifetime HTT were predictive of the frequencies of these strains in wild <em>I. scapularis</em> populations. For <em>B. burgdorferi</em>, the strains that establish high abundance in host tissues and that have high lifetime transmission are the strains that are most common in nature.</p>
A major myna problem; invasive predator removal benefits female survival and population growth of a translocated island endemic
<p>Invasive predators are a major driver of extinctions and continue to threaten native populations worldwide. Island eradications of (mostly mammalian) invasive predators have facilitated the reestablishment of numerous island-endemic populations. Other invasive taxa, such as some predatory birds, could pose a more persistent threat due to their ability to fly and actively re-invade even remote and isolated islands. However, the impact of invasive predatory birds has been largely overlooked. We report on a novel sex-specific impact of an invasive-nest predator, the common myna (<span><em>Acridotheres</em> <em>tristis</em></span>), on a reintroduced population of Seychelles warblers (<span><em>Acrocephalus</em> <em>sechellensis</em></span>); translocated from Cousin Island to Denis Island in 2004. Regular post-translocation monitoring revealed that female mortality was 20 % higher than males, leading to a 60<span>–</span>70 % male-biased population sex-ratio between 2005 and 2015. This was attributed to common mynas inflicting severe injuries to incubating female Seychelles warblers while attempting to prey upon eggs in their nests. These effects likely contributed to the slower-than-expected population growth observed (relative to previous translocations of Seychelles warblers to other islands) over the same period. An eradication programme beginning in 2011 removed all common mynas from Denis by 2015. Subsequently, we observed a balancing of sex-specific survival and the population sex-ratio of Seychelles warblers and, consequently, accelerated population growth. This study demonstrates the importance of assessing the threat posed by all invasive taxa (not just mammals) to island conservation. Furthermore, we show how extended monitoring is needed to identify problems and develop solutions, post-translocation.</p>
Is my model fit for purpose? Validating a population model for predicting freshwater fish responses to flow management
<p>Models based on ecological processes ("process-explicit models") are often used to predict ecosystem responses to environmental changes or management scenarios. However, models are imperfect and need to be validated, ideally by testing their assumptions and outputs against independent empirical data sets. Examples of validation of process-explicit models are rare. Recently, stochastic population models have been developed to predict the likely responses (over 10-120 years) of a riverine fish (golden perch, Macquaria ambigua) to flow management in the Murray-Darling Basin (MDB) in eastern Australia, one of the world's most regulated river basins. Declines of golden perch (and other species) are a direct consequence of altered hydrology, and managers require information to predict how fish will respond to possible future hydrological conditions to guide the substantial investments in flow management. Here, we use two independent field data sets to validate our population model. We compared model predictions to observed trends to ask: (1) how do predicted population sizes and growth rates compare to observed data? (2) does the correlation between predicted and observed population sizes and growth rates vary among populations? (3) does the correlation between predicted and observed population sizes and growth rates vary across observed hydrological conditions? and (4) how do modelled and observed fish movement rates compare? We found reasonable correlations between fish population sizes and growth rates as predicted by the model and observed in independent data sets for several populations (Aim 1) but the strength of these correlations varied among populations (Aim 2) and hydrological conditions (Aim 3). Predicted and observed fish movement rates were strongly correlated (Aim 4). Population models are frequently used in conservation decision-making but are rarely validated. We demonstrate that: (1) validation can identify model strengths and weaknesses; (2) observed data sets often have inherent limitations that can preclude robust validations; (3) validation is likely be more common if appropriate observed data sets are available; and (4) validation should consider the purpose of modelling. Wider consideration of these messages would contribute to more critical examinations of models so they can be most appropriately used in conservation decision-making.</p>
ScienceDex guides
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.