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The biogeochemistry of tidal marsh sediments facilitates the transformation of mercury (Hg) into the biologically available form methylmercury (MeHg), resulting in elevated Hg exposures to tidal marsh wildlife. Saltmarsh and Acadian Nelson’s sparrows (Ammospiza caudacutua and A. nelsoni subvirgatus, respectively) exclusively inhabit tidal marshes, potentially experiencing elevated risk to Hg exposure, and have experienced range-wide population declines. To characterize spatial and temporal variation of Hg exposure in these species, we sampled total mercury (THg) in blood collected from 9 populations spanning 560 km of coastline, including individuals resampled within and among years. Using concurrent nesting studies, we tested whether THg was correlated with nest survival probabilities, an index of fecundity. Blood THg ranged from 0.074–3.373 µg/g ww across 170 samples from 127 individuals. We detected high spatial variability in Hg exposure, observing differences of more than 45-fold across all individuals and 8-fold in mean blood THg among all study plots, including 4-fold between study plots within 4 km. Intraindividual changes in blood Hg exposure did not vary systematically in time but were considerable, varying by up to 2-fold within and among years. Controlling for both species differences and maximum water level, the dominant driver of fecundity in this system, nest survival probability decreased by 10% across the full range of female blood THg concentrations observed. We conclude that Hg has the potential to impair songbird reproduction, potentially exacerbating known climate-change driven population declines from sea-level rise in saltmarsh and Acadian Nelson’s sparrows.

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 (Dolichonyx oryzivorus), 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. Fst 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.

Oroanthral fistula (anastomosis) is an element preventing the restoration of homeostasis in the maxillary sinus due to the constant flow of microbes from the oral cavity. It is also contributes to frequent exacerbations of maxillary sinusitis. Saprophytic gram-positive cocci and fungi of the oral cavity are dominating representatives of the microbial flora in the maxillary sinus. As the result of research, we found that in the case of maxillary sinusitis with oroantral fistula fungi made up 25.0% of microbiota, gram-positive bacteria – 41.7%, gram-negative bacteria – 33.3%. Gram-positive cocci from the Staphy­lococcus genus (Staphylococcus aureus and Staphylococcus epidermidis) and fungi (Candida albicans) comprised the biggest proportion of microbial flora that 33.3% and 16.7%, respectively. Slightly decreased levels of monocytes in venous blood was noted in 69.2% of patients. The average value of total serum IgE in group with oroantal fistula was 226.2 (70.4) IU/ml, the result exceeded normal limits almost in 2.26 times. Large circulating immune complexes (CICs) were normal in all patients in the group with iatrogenic maxillary sinusitis. The average lavels of small size CICs was 170.2 (4.23)ОU, which is in 1.06 times higher the upper limit of the norm (160ОU). Elevated levels of total Ig E in serum of patients with oroanthral fistula indicates allergic sensitization. The detection of increased levels of CICs with small and medium sizes in serum may indicate a susceptibility of this category of patients to the development of immunopathological reactions.

Linking genotype to phenotype is a primary goal for understanding the genomic underpinnings of evolution. However, little work has explored whether patterns of linked genomic and phenotypic differentiation are congruent across natural study systems and traits. Here, we investigate such patterns with a meta‐analysis of studies examining population‐level differentiation at subsets of loci and traits putatively responding to divergent selection. We show that across the 31 studies (88 natural population‐level comparisons) we examined, there was a moderate (R 2 = 0.39) relationship between genomic differentiation (F ST) and phenotypic differentiation (PST ) for loci and traits putatively under selection. This quantitative relationship between P ST and F ST for loci under selection in diverse taxa provides broad context and cross‐system predictions for genomic and phenotypic adaptation by natural selection in natural populations. This context may eventually allow for more precise ideas of what constitutes “strong” differentiation, predictions about the effect size of loci, comparisons of taxa evolving in nonparallel ways, and more. On the other hand, links between P ST and F ST within studies were very weak, suggesting that much work remains in linking genomic differentiation to phenotypic differentiation at specific phenotypes. We suggest that linking genotypes to specific phenotypes can be improved by correlating genomic and phenotypic differentiation across a spectrum of diverging populations within a taxon and including wide coverage of both genomes and phenomes.

The saltmarsh sparrow Ammospiza caudacuta and Nelson's sparrow A. nelsoni differ in ecological niche, mating behavior, and plumage, but they hybridize where their breeding distributions overlap. In this advanced hybrid zone, past interbreeding and current backcrossing result in substantial genomic introgression in both directions, although few hybrids are currently produced in most locations. However, because both species are nonterritorial and have only brief male–female interactions, it is difficult to determine to what extent assortative mating explains the low frequency of hybrid offspring. Since females often copulate with multiple males, a role of sperm as a postcopulatory prezygotic barrier appears plausible. Here, we show that sperm length differs between the two species in the hybrid zone, with low among‐male variation consistent with strong postcopulatory sexual selection on sperm cells. We hypothesize that divergence in sperm length may constitute a reproductive barrier between species, as sperm length co‐evolves with the size of specialized female sperm storage tubules. Sperm does not appear to act as a postzygotic barrier, as sperm from hybrids was unexceptional., Sperm length differs between saltmarsh and Nelson's sparrows, two species that hybridize, and length correlates with both hybrid index (based on 135 SNPs) and plumage index. This divergence in sperm phenotype may act as a reproductive barrier between species.

BackgroundExploring hybrid zone dynamics at different spatial scales allows for better understanding of local factors that influence hybrid zone structure. In this study, we tested hypotheses about drivers of introgression at two spatial scales within the Saltmarsh Sparrow (Ammospiza caudacuta) and Nelson’s Sparrow (A. nelsoni) hybrid zone. Specifically, we evaluated the influence of neutral demographic processes (relative species abundance), natural selection (exogenous environmental factors and genetic incompatibilities), and sexual selection (assortative mating) in this mosaic hybrid zone. By intensively sampling adults (n = 218) and chicks (n = 326) at two geographically proximate locations in the center of the hybrid zone, we determined patterns of introgression on a fine scale across sites of differing habitat. We made broadscale comparisons of patterns from the center with those of prior studies in the southern edge of the hybrid zone.ResultsA panel of fixed SNPs (135) identified from ddRAD sequencing was used to calculate a hybrid index and determine genotypic composition/admixture level of the populations. Another panel of polymorphic SNPs (589) was used to assign paternity and reconstruct mating pairs to test for sexual selection. On a broad-scale, patterns of introgression were not explained by random mating within marshes. We found high rates of back-crossing and similarly low rates of recent-generation (F1/F2) hybrids in the center and south of the zone. Offspring genotypic proportions did not meet those expected from random mating within the parental genotypic distribution. Additionally, we observed half as many F1/F2 hybrid female adults than nestlings, while respective male groups showed no difference, in support of Haldane’s Rule. The observed proportion of interspecific mating was lower than expected when accounting for mate availability, indicating assortative mating was limiting widespread hybridization. On a fine spatial scale, we found variation in the relative influence of neutral and selective forces between inland and coastal habitats, with the smaller, inland marsh influenced primarily by neutral demographic processes, and the expansive, coastal marsh experiencing higher selective pressures in the form of natural (exogenous and endogenous) and sexual selection.ConclusionsMultiple drivers of introgression, including neutral and selective pressures (exogenous, endogenous, and sexual selection), are structuring this hybrid zone, and their relative influence is site and context-dependent.

The biogeochemistry of tidal marsh sediments facilitates the transformation of mercury (Hg) into the biologically available form methylmercury (MeHg), resulting in elevated Hg exposures to tidal marsh wildlife. Saltmarsh and Acadian Nelson's sparrows (Ammospiza caudacutua and A. nelsoni subvirgatus, respectively) exclusively inhabit tidal marshes, potentially experiencing elevated risk to Hg exposure, and have experienced range-wide population declines. To characterize spatial and temporal variation of Hg exposure in these species, we sampled total mercury (THg) in blood collected from 9 populations spanning 560 km of coastline, including individuals resampled within and among years. Using concurrent nesting studies, we tested whether THg was correlated with nest survival probabilities, an index of fecundity. Blood THg ranged from 0.074-3.373 µg/g ww across 170 samples from 127 individuals. We detected high spatial variability in Hg exposure, observing differences of more than 45-fold across all individuals and 8-fold in mean blood THg among all study plots, including 4-fold between study plots within 4 km. Intraindividual changes in blood Hg exposure did not vary systematically in time but were considerable, varying by up to 2-fold within and among years. Controlling for both species differences and maximum water level, the dominant driver of fecundity in this system, nest survival probability decreased by 10% across the full range of female blood THg concentrations observed. We conclude that Hg has the potential to impair songbird reproduction, potentially exacerbating known climate-change driven population declines from sea-level rise in saltmarsh and Acadian Nelson's sparrows.

The role of species divergence due to ecologically based divergent selection—or ecological speciation—in generating and maintaining biodiversity is a central question in evolutionary biology. Comparison of the genomes of phylogenetically related taxa spanning a selective habitat gradient enables discovery of divergent signatures of selection and thereby provides valuable insight into the role of divergent ecological selection in speciation. Tidal marsh ecosystems provide tractable opportunities for studying organisms' adaptations to selective pressures that underlie ecological divergence. Sharp environmental gradients across the saline–freshwater ecotone within tidal marshes present extreme adaptive challenges to terrestrial vertebrates. Here, we sequence 20 whole genomes of two avian sister species endemic to tidal marshes—the saltmarsh sparrow (Ammospiza caudacutus) and Nelson's sparrow (A. nelsoni)—to evaluate the influence of selective and demographic processes in shaping genome‐wide patterns of divergence. Genome‐wide divergence between these two recently diverged sister species was notably high (genome‐wide F ST = 0.32). Against a background of high genome‐wide divergence, regions of elevated divergence were widespread throughout the genome, as opposed to focused within islands of differentiation. These patterns may be the result of genetic drift resulting from past tidal march colonization events in conjunction with divergent selection to different environments. We identified several candidate genes that exhibited elevated divergence between saltmarsh and Nelson's sparrows, including genes linked to osmotic regulation, circadian rhythm, and plumage melanism—all putative candidates linked to adaptation to tidal marsh environments. These findings provide new insights into the roles of divergent selection and genetic drift in generating and maintaining biodiversity., Whole‐genome comparisons of two congeneric sparrows with different levels of specialization to tidal marsh environments revealed that both genetic drift and divergent ecological selection influenced the speciation process. Against a background of high genome‐wide divergence brought about by drift, regions of elevated divergence were widespread throughout the genome. These regions contained genes relating to tidal marsh adaptations, including those putatively functioning in osmotic regulation, circadian rhythm, and plumage melanism, and suggests a role for ecological speciation in the divergence of the saltmarsh and Nelson's sparrow.

Changes in the frequency and severity of extreme weather may introduce new threats to species that are already under stress from gradual habitat loss and climate change. We provide a probabilistic framework that quantifies potential threats by applying concepts from ecological resilience to single populations. Our approach uses computation to compare disturbance-impacted projections to a population's normal range of variation, quantifying the full range of potential impacts. We illustrate this framework with projection models for coastal birds, which are commonly depicted as vulnerable to disturbances, especially hurricanes and oil spills. We found that populations of coastal specialists are resilient to extreme disturbances, with high resistance to the effects of short-term reductions in vital rates and recovery within 20 years. Applying the general framework presented here across disturbance-prone species and ecosystems would improve understanding of population resilience and generate specific projections of resilience that are needed for effective conservation planning.

Theory suggests that different taxa having colonized a similar, challenging environment will show parallel or lineage-specific adaptations to shared selection pressures, but empirical examples of parallel evolution in independent taxa are exceedingly rare. We employed comparative genomics to identify parallel and lineage-specific responses to selection within and among four species of North American sparrows that represent four independent, post-Pleistocene colonization events by an ancestral, upland subspecies and a derived salt marsh specialist. We identified multiple cases of parallel adaptation in these independent comparisons following salt marsh colonization, including selection of 12 candidate genes linked to osmoregulation. In addition to detecting shared genetic targets of selection across multiple comparisons, we found many novel, species-specific signatures of selection, including evidence of selection of loci associated with both physiological and behavioral mechanisms of osmoregulation. Demographic reconstructions of all four species highlighted their recent divergence and small effective population sizes, as expected given their rapid radiation into saline environments. Our results highlight the interplay of both shared and lineage-specific selection pressures in the colonization of a biotically and abiotically challenging habitat and confirm theoretical expectations that steep environmental clines can drive repeated and rapid evolutionary diversification in birds.

An understanding of genetic diversity and population structure is important to the conservation of declining species within fragmented habitats. These issues become critical for small, isolated populations, in which stochasticity is a main driver of genetic change and possibly of population extinction. In eastern New York and New England the endemic New England cottontail has declined due to habitat loss and fragmentation. As a species that exhibits metapopulation dynamics, habitat fragmentation can have profound implications for its persistence. We examined genetic diversity, population structure, and effective population size (Ne) of New England cottontails in New York, a purported remnant stronghold for the species. We amplified ten microsatellite loci from tissues collected from live-captures and from fecal pellets. We investigated potential hierarchical population structuring using programs STRUCTURE and BAPS. STRUCTURE identified four hierarchical tiers consisting of nine clusters, and BAPS clustering was highly consistent with that given by STRUCTURE. Most populations displayed significant genetic differentiation (FST = 0.04–0.34) and little to no evidence of ongoing connectivity. Low genetic diversity was observed based on allelic richness (2.2–3.0), and all populations had critically low effective population sizes (Ne; 2.7–57.1). Observed trends in population subdivision, genetic diversity, and Ne were consistent with reported trends in the state-endangered Maine-New Hampshire populations, and not indicative of a genetic stronghold within New York. Instead, the small and isolated populations observed here imply a breakdown in metapopulation functionality indicative of conditions faced by the species range-wide and an immediate need for human intervention to restore connectivity and rebuild populations.

The implementation of the fundamentals and principles of the formation of integrated reporting, embodied in the International Framework for Integrated Reporting, requires the development of its proper structure. The need for a generally accepted structure of integrated reporting is conditioned by the lack of relevant information both in normative acts and in the scientific and practical comments. It updates the issue of streamlining the information of the entity, disclosed in the integrated reporting, and the development of an appropriate structure of the integrated reporting for its disclosure. The purpose of the study is to improve the structure of integrated reporting by disclosing the composition of elements of such a structure. To achieve this goal, such scientific methods as analysis, synthesis, induction, deduction, abstraction, idealization, generalization and modeling will be used. The proposed list of elements of the structure of integrated reporting can not be considered comprehensive, since the specificity of each enterprise’s activity requires either additional disclosure of the required information in such elements of the integrated reporting structure or the exclusion of individual elements of its structure, if they are not specific to a particular activity. In the comparative structure of the elements of integrated reporting under the International Fundamentals of Integrated Reporting and authors’ approaches, the most significant elements of them are systematized that expand the information capabilities of such reporting, and their unfounded neglect reduces the completeness of disclosure in integrated reporting. According to the results of the study, proposals were made to improve the structure of integrated reporting, by disclosing information for each element of integrated reporting, which will provide a sufficient level of detail information for the purpose of making economic decisions by relevant groups of interested users.

The Saltmarsh Sparrow (Ammospiza caudacuta) is a tidal marsh bird facing rapid population decline throughout its range, largely caused by degradation and loss of breeding habitat. Thus, there is a need to preserve tidal marshes in the northeastern United States, but to do so requires an understanding of the habitat features that support robust populations. Previous studies have shown Saltmarsh Sparrow abundance increases with marsh size, but in similar bird species, area sensitivity is more directly linked to edge avoidance. Whether additional landscape features affect the abundance of Saltmarsh Sparrows is unknown. We explored how the height of objects on the horizon, an index of habitat openness, affected the abundance of Saltmarsh Sparrows. Our primary goal was to determine whether the angle to the highest point on the horizon (“angle to maximum horizon”) predicted abundance better than marsh area or distance to the marsh edge. We used N-mixture models to evaluate the combination of spatial factors that best predicted Saltmarsh Sparrow abundance while also accounting for survey-level variables that could influence detection probability. We found that the interaction between distance to edge and angle to maximum horizon best predicted abundance. Taller objects on the horizon were negatively correlated with bird abundance, and this effect was strongest within 50 m of the marsh edge. When we considered the predictive powers of patch area, distance to edge, and angle to maximum horizon individually, angle to maximum horizon was the best single predictor. We found the highest abundance of Saltmarsh Sparrows at point locations where the angle to maximum horizon was 0.0°, and at angles greater than 12° the predicted abundance fell below 1 bird per survey point. We propose that managers should prioritize marsh openness and experimentally test the effect of marsh edge manipulations when making conservation decisions for this rapidly declining species.

There was con­ducted study of dynamics of findings of non-specific resistance in the mouth cavity in children with lesions of the mucous membrane epithelium of the mouth cavity against acute lymphoblastic leukemia in the treatment process by authors-developed methods. It is known that in children with leukemia immunodeficiency states develop immunological disorders resulted from treatment with cytotoxic drugs. Moreover, not only general, but also the local immunity of the mouth cavity suffers, which is accompanied by development of infectious processes in the tissues that perform the barrier function, which include mucous membrane epithelium of the mouth cavity. A key role in the system of antimicrobial protection of the mouth cavity is performed by mucolytic enzyme lisocyme and α-defensins (HNP 1-3). 76 children with acute lymphoblastic leukemia aged from 2 to 18 years suffering from such dental diseases as generalized chronic catarrhal gingivitis, erosive-ulcerative and candidal stomatitis took part in the clinical study. All children under clinical study were divided into 2 groups - the main and comparison. Standard protocol treatment was used in the comparison group. Developed treatment-and-prophylactic complex was used in the main group. The children of the main group were prescribed developed treatment-and-prophylactic complex depending on the period of the disease: the first version of local treatment was used in the acute period and the relapse of the disease, the second - in the period of remission. The results of research have shown a stimulating effect of therapeutic and prophylactic measures on the natural antimicrobial system of mouth cavity protection, both in children of the main groups under study and in the comparison groups. Such a phenomenon should be considered as a positive process that contributes to the increase of resistance in periodontal tissues and mucous membrane epithelium of the mouth cavity.

Insufficient time and funding remain obstacles to collecting data across broad spatial scales on the fine-scale distribution of multiple species, their life histories, and interactions with other species and the environment. This often necessitates the use of focal species to inform conservation and management decisions. We used the systematic conservation-planning software Marxan to assess quantitatively whether a focal species can aid in conservation and management of tidal marsh birds. Using a metric of relative cost in the region and current protected areas, we identified priority areas for conservation of 5 specialist taxa—Clapper Rail (Rallus crepitans), Eastern Willet (Tringa semipalmata semipalmata), Acadian Nelson's Sparrow (Ammospiza nelsoni subvirgatus), Saltmarsh Sparrow (A. caudacuta), and Seaside Sparrow (A. maritima)—that nest primarily in tidal marshes in the northeastern United States. We compared the spatial prioritization of sites and cost-effectiveness of alternative protectio...

The subject of the study is represented by errors which were made in financial statements of prior periods and order of adjusting them according to International Financial Reporting Standards (IFRS). The objective of the research was set to study out the materiality of errors made in financial statements of prior periods, determination of classification and order of adjusting the errors in accordance with IFRS. Different methods were used for achieving set up goals: induction and deduction, analysis, synthesis, causal relationships, abstractly logical, comparison, studying monographs and other generally accepted methods. According to IFRS errors might be made while recognizing, measuring, submitting and disclosing information about elements of financial statements. IFRS 8 divides such errors to errors of current period and prior reporting periods. Errors of prior reporting periods may influence or not influence the amount of undivided profit, material or not material, also intentional or not intentional. IFRS/IAS do not set up any recommendations about quantity or quality criteria or characteristics of materiality of errors. Every business entity preparing financial reports sets up materiality of errors based on their own criteria of materiality of errors. According to IRFS 8 paragraph 42 business entities adjust material mistakes of the prior period retrospectively in the first set of financial statements confirmed before its disclosing after their revealing. There are two ways to adjust these kind of errors: by transferring comparable sums for prior period (periods) presented when the mistake was made. Also by transferring the residue of assets, liabilities and equity in the beginning of the period for the earliest of the prior period presented, if the errors were made before the earliest of the prior period presented. Information about errors of prior period must be disclosed. Practical use of the research consists in bringing its main ideas to life through methodical innovations and recommendations which may be applied while adjusting errors, by business entities preparing financial statements according to IFRS.

If individuals can perceive and manage risks, they may alter their behaviors based on prior experience. This expectation may apply to nest site selection of breeding birds, for which adaptive behavioral responses may enhance fitness. Birds that nest in tidal marshes have adapted to the challenges posed primarily by periodic, monthly tidal flooding and secondarily by predation. We investigated adaptive responses in nesting behavior of the saltmarsh sparrow (Ammospiza caudacutus), an obligate tidal‐marsh‐breeding bird, using 536 nests monitored across 5 years. Using linear mixed effects models, we tested whether nest characteristics differed among nests that were successful, depredated, or flooded, and we investigated whether females made changes in nest structure and placement according to outcome of their previous nesting attempt. Nest characteristics differed among females with different nest fates. Fledged and depredated nests were built higher in the vegetation and in higher elevation areas of the marsh than those that flooded. Successful nests had more canopy cover and were comprised of a lower proportion of high marsh vegetation (Spartina patens) than those that were flooded or depredated. Females with nests that failed due to flooding constructed subsequent nests higher in the vegetation and at higher elevation than those that were successful in their prior attempt, consistent with a response to previous experience. Eighty‐five percent of females renested within the average home range core area distance (77 m), indicating a high degree of nest placement fidelity. Females for which nests were depredated in their prior nesting attempt renested at a greater distance than females for which the previous nesting attempts were successful. Our findings suggest saltmarsh sparrows exhibit plasticity in nesting behavior, which may be important for balancing selective pressures in a dynamic environment. This plasticity, however, is insufficient to enable them to adapt to the increased flooding predicted with sea‐level rise.

Striped bass (Morone saxatilis) and their hybrids have been well studied and are widely cultured in freshwater ponds as food and gamefish. Recent industry expansion has generated an interest in strain-specific broodstock development for marine netpen and pond culture. In this effort, Atlantic and Gulf coast striped bass strains were cultured in recirculating aquaculture systems (RAS) at different salinities for up to two years and production and morphometric parameters (specific growth, feed conversion, fillet yield, condition factor and stripe patterns) were compared. Striped bass juveniles produced from wild-caught broodstock from rivers in Nova Scotia, Delaware, Virginia, North and South Carolina, Florida, Texas and a selected, domesticated strain were reared in triplicate fresh (0 ppt), brackish (5 ppt) and saltwater recirculating (30 ppt) systems. After one year of age, a subset of fish were implanted with passive integrated transponder (PIT) tags, combined into a larger, “common-garden”, saltwater, recirculating system and monitored over an additional year. Parental broodstock and cultured offspring were fin-clipped and genotyped to identify juvenile family origin. Final weights of fish after one and two years averaged approximately 0.5 and 2.5 kg, respectively and did not differ by water salinity. Growth rates and condition factors differed by strain, but condition factor was not correlated with fillet yield. Consistent with other studies, juvenile fish from South Carolina and Nova Scotia were found to be slow growing compared to migratory Atlantic and Gulf strains. Mixed model analyses showed that family, and family by strain interactions were significant, but accounted for less growth variance than strain alone. These results indicate that family-based selection by strain may be useful in striped bass broodstock development programs.

Understanding inter- and intra-specific variation in mate compatibility and reproductive success can offer insight into the factors driving sexual selection, behavioral dynamics, and isolating mechanisms across natural populations. This information is particularly relevant when trying to understand the patterns that shape the causes and outcomes of hybridization in natural systems. We evaluated mating patterns and male reproductive success in a hybrid zone between the Saltmarsh (Ammodramus caudacutus) and Nelson's sparrow (A. nelsoni). Specifically, we investigated variation in male reproductive success between pure Saltmarsh and pure Nelson's sparrows and between pure and hybrid males, while testing for assortative vs. random mating. DNA samples were collected from adults (n = 342) and nestlings (n = 348), and paternity analyses and assignment of individuals to pure and hybrid classes were conducted using 11 microsatellite loci. We documented high promiscuity and reproductive skew in Saltmarsh a...

Evolutionary theory suggests that natural selection should favor the ability of animals to modify their offspring sex ratios when the fitness benefits of producing one sex over the other vary in relation to environmental conditions. The Saltmarsh Sparrow (Ammodramus caudacutus) is an extreme habitat specialist, with breeding behavior influenced by the tidal cycle. The challenges of nesting in the harsh environment of salt marshes and the unique promiscuous mating system of the Saltmarsh Sparrow provide a context for offspring sex ratio manipulation. We investigated adaptive sex ratio manipulation in this system across multiple sites and years using a mixed modeling approach. We collected data on nest initiation and nestling survival from 370 nests of 210 females during 2011–2015 in 4 marshes in the northeastern United States. Using molecular techniques, we determined the sex of 990 offspring and characterized variation in site- and population-level sex ratios. Using binomial linear mixed-effects ...

Demographic rates are rarely estimated over an entire species range, limiting empirical tests of ecological patterns and theories, and raising questions about the representativeness of studies that use data from a small part of a range. The uncertainty that results from using demographic rates from just a few sites is especially pervasive in population projections, which are critical for a wide range of questions in ecology and conservation. We developed a simple simulation to quantify how this lack of geographic representativeness can affect inferences about the global mean and variance of growth rates, which has implications for the robust design of a wide range of population studies. Using a coastal songbird, saltmarsh sparrow (Ammodramus caudacutus), as a case study, we first estimated survival, fecundity, and population growth rates at 21 sites distributed across much of their breeding range. We then subsampled this large, representative dataset according to five sampling scenarios in order to simulate a variety of geographic biases in study design. We found spatial variation in demographic rates, but no large systematic patterns. Estimating the global mean and variance of growth rates using subsets of the data suggested that at least 10-15 sites were required for reasonably unbiased estimates, highlighting how relying on demographic data from just a few sites can lead to biased results when extrapolating across a species range. Sampling at the full 21 sites, however, offered diminishing returns, raising the possibility that for some species accepting some geographical bias in sampling can still allow for robust range-wide inferences. The sub-sampling approach presented here, while conceptually simple, could be used with both new and existing data to encourage efficiency in the design of long-term or large-scale ecological studies. This article is protected by copyright. All rights reserved.

The balance of abiotic and biotic stressors experienced by a species likely varies across its range, resulting in spatially heterogeneous limitations on the species' demographic rates. Support for spatial variation in stressors (often latitudinal gradients) has been found in many species, usually with physiological or correlative occupancy data, but it has rarely been estimated directly with demographic data. We collected demographic data from 23 sites spanning the majority of the Saltmarsh Sparrow (Ammodramus caudacutus) breeding range. Using data from 837 nests, we quantified the abiotic and biotic variables most important to nest survival, which is the dominant driver of both fecundity and population growth rate in this species. We separately estimated daily nest failure probability due to nest depredation (biotic stressor) and nest flooding (abiotic stressor), which collectively account for almost all nest failure in the species. Nest depredation decreased with latitude, whereas nest flooding...

Conservation of threatened or endangered species in a hybrid zone requires a comprehensive understanding of interspecific dynamics over time and space. We evaluated changes in location and composition of a hybrid zone over a 15-year period (with replicated sampling in 1997–2000 and 2011–2013) for saltmarsh (Ammodramus caudacutus) and Nelson’s (A. nelsoni) sparrows, two tidal marsh specialists of high conservation priority in the northeastern United States. We combined genetic analyses using microsatellite and mitochondrial markers with species distribution patterns. In both time periods, replicate genetic sampling (n = 85; five sites) and field population surveys (93 sites) were conducted. We compared the distribution of parental species and hybrids and estimates for hybrid zone width and center between the two time periods. An increase in the relative proportion of Nelson’s sparrows in sympatric marshes and an approximate doubling of hybrid zone width provides evidence for expansion. Introgression rates increased over time for neutral loci but declined for a mitochondrial gene and two gene-associated loci under the influence of selection, as expected under a speciation model with barriers to gene flow. On average, the center of the hybrid zone shifted 60 km southward over the 15 years. We placed our findings within a policy framework to evaluate management options for hybrids. We conclude that despite increasing rates of introgression, hybridization poses a substantially lesser threat to parental populations than the imminent consequences of sea-level rise and habitat degradation. Based on our current knowledge of hybrid zone dynamics in this system, we conclude that the conservation of hybrids is warranted along with parental species at this time.

A body of research by Russell Greenberg, Glenn Tattersall and their colleagues has proposed a corollary of Allen's Rule: that in freshwater‐limited environments, bill surface area increases with temperature. Increases in both population density and sexual dimorphism, however, could also explain increases in bill surface area. After controlling for the effects of a hybrid zone, we tested whether temperature or population density in the saltmarsh sparrow Ammospiza caudacuta, a sexually monomorphic estuarine specialist, explained greater variance in bill surface area. This allowed us to examine multiple potential selective mechanisms underlying the Greenberg–Tattersall corollary. We found that saltmarsh sparrows follow the general pattern of the corollary (larger bills in warmer summer climates) but only after controlling for population density. The relationship between bill surface area and temperature varied inversely with population density. We discuss the relative abilities of sexual selection and ecological competition to explain these results.

Atlantic cod (Gadus morhua) populations in the Gulf of Maine (GoM) are at a fraction of their historical abundance, creating economic hardships for fishermen and putting at risk the genetic diversity of the remaining populations. An understanding of the biocomplexity among GoM populations will allow for adaptive genetic diversity to be conserved to maximize the evolutionary potential and resilience of the fishery in a rapidly changing environment. We used restriction-site-associated DNA sequencing (RADseq) to characterize the population structure and adaptive genetic diversity of five spawning aggregations from the western GoM and Georges Bank. We also analyzed cod caught in the eastern GoM, an under-sampled area where spawning aggregations have been extirpated. Using 3,128 single nucleotide polymorphisms (SNPs), we confirmed the existence of three genetically separable spawning groups: (1) winter spawning cod from the western GoM, (2) spring spawning cod, also from the western GoM, and (3) Georges Bank cod. Non-spawning cod from the eastern GoM could not be decisively linked to either of the three spawning groups and may represent a unique component of the resource, a mixed sample, or cod from other unsampled source populations. The genetic differentiation among the three major spawning groups was primarily driven by loci putatively under selection, particularly loci in regions known to contain genomic inversions on linkage groups (LG) 7 and 12. These LGs have been found to be linked to thermal regime in cod across the Atlantic, and so it is possible that variation in timing of spawning in western GoM cod has resulted in temperature-driven adaptive divergence. This complex population structure and adaptive genetic differentiation could be crucial to ensuring the long-term productivity and resilience of the cod fishery, and so it should be considered in future management plans.

Seventy-one tank spawning trials were conducted to evaluate the efficacy of exogenous hormone compounds and a novel “pace-set” strategy for inducing volitional tank spawning behavior in 5th generation domestic striped bass. Female fish (4.74 ± 0.73 kg; mean ± standard deviation) were treated with human chorionic gonadotropin (hCG; 29 trials), gonadotropin releasing hormone analog (GnRHa; 39 trials) or received no hormone treatment (control; 3 trials). Spawning trials were conducted using single females placed in spawning tanks with two (12 trials) or three (38 trials) males or with paired females placed in spawning tanks with three (4 trials) males. Significant differences in egg production, fry production, hatching rate, and fry/kg female body weight were generally not observed between exogenous hormone treatment groups (alpha = 0.05), with the exception of egg production differing between paired females spawning with three males (Student's t-test, p = 0.0255). However, a trend suggesting that increasing the number of males or females within the tanks improves yield of larvae (fry/kg female body weight) was observed. The untreated control females failed to spawn within 7 days. The pace-set spawning was conducted whereby one female treated with either hCG (7 trials) or GnRHa (7 trials) was placed in a spawning tank with one untreated female and multiple males. The results of these trials show for the first time that a hormone-induced female striped bass can be used to stimulate successful volitional spawning of an untreated female in the same tank with fry/kg female body weight production similar to that of hormone-treated fish. Microsatellite-based parentage of select tank spawns and four additional trials conducted with an increased number of males (19 trials total) showed that female striped bass typically spawn with at least two males; a single pair mating was only observed for one spawning trial. These data allowed for the determination of effective broodstock size (Nb) of each tank spawning trial at between 2.00 and 5.60 when considering all male contributions. The Nb generally increased as the number of males and female fish in the tank increased (from 2.53 for one female and two males to 5.52 for two females and six males). These results indicate that domestic striped bass are promiscuous and will generally reproduce in captivity using tank spawning procedures that allow for a high level of genetic diversity to be retained among the offspring. The pace-set method reduces hormone use and may be applied to commercial striped bass production as well as captive spawning of other fish species.

The range of a species is determined by the balance of its demographic rates across space. Population growth rates are widely hypothesized to be greatest at the geographic center of the species range, but indirect empirical support for this pattern using abundance as a proxy has been mixed, and demographic rates are rarely quantified on a large spatial scale. Therefore, the texture of how demographic rates of a species vary over its range remains an open question. We quantified seasonal fecundity of populations spanning the majority of the global range of a single species, the saltmarsh sparrow (Ammodramus caudacutus), which demonstrates a peak of abundance at the geographic center of its range. We used a novel, population projection method to estimate seasonal fecundity inclusive of seasonal and spatial variation in life history traits that contribute to seasonal fecundity. We replicated our study over 3 years, and compared seasonal fecundity to latitude and distance among plots. We observed large-scale patterns in some life history traits that contribute to seasonal fecundity, such as an increase in clutch size with latitude. However, we observed no relationship between latitude and seasonal fecundity. Instead, fecundity varied greatly among plots separated by as little as 1 km. Our results do not support the hypothesis that demographic rates are highest at the geographic and abundance center of a species range, but rather they suggest that local drivers strongly influence saltmarsh sparrow fecundity across their global range.

The effects of hybridization on evolutionary processes are primarily determined by the differential between hybrid and parental species fitness. Assessing the impacts of hybridization can be challenging, however, as determining the relationship between individual fitness and the extent of introgression in wild populations is difficult. We evaluated the fitness consequences of hybridization for pure and hybrid females in a hybrid zone between two tidal marsh birds, the saltmarsh sparrow (Ammodramus caudacutus), a salt marsh obligate, and Nelson's sparrow (A. nelsoni), which has a broader ecological niche and a much younger evolutionary association with salt marshes. Biotic stressors associated with nesting in tidal environments suggest an important role for differential adaptation in shaping hybrid zone dynamics, with saltmarsh sparrows predicted to be better adapted to nesting in salt marshes. We collected DNA samples from adults (n = 394) and nestlings (n = 431) to determine the extent of introgression using 12 microsatellite loci and tested for the influence of extrinsic (nest placement) and intrinsic (genotype) factors on female reproductive success. We monitored nests (n = 228), collected data on reproductive output, and estimated daily nest survival rates using female genotype and nest characteristics as covariates. To test for reduced survival of hybrid females, we also used capture data to assess the distribution of admixed male and female individuals across age classes. Reproductive success of females varied by genotypic class, but hybrids did not have intermediate success as predicted. Instead, we found that pure Nelson's sparrows had, on average, 33% lower hatching success than any other genotype, whereas F1/F2 hybrids, backcrossed Nelson's sparrows, and backcrossed and pure saltmarsh sparrows all had similar hatching success. We found no effect of genotype or nest placement on daily nest survival probabilities. However, hybrid individuals with a higher proportion of saltmarsh sparrow alleles exhibit nesting behaviours better suited to nesting successfully in tidal marshes. Further, while the proportion of F1/F2 individuals was similar between nestling and adult males, we found that the proportion of F1/F2 individuals was 2.3 times greater in nestling females compared with adult females, indicating reduced survival of F1 females. We conclude that differences in reproductive success among pure and admixed individuals coupled with intrinsic mechanisms (reduced survival in F1 females) shape hybrid zone dynamics in this system.

Selection can create complex patterns of adaptive differentiation among populations in the wild that may be relevant to management. Atlantic cod in the Northwest Atlantic are at a fraction of their historical abundance and a lack of recovery within the Gulf of Maine has created concern regarding the misalignment of fisheries management structures with biological population structure. To address this and investigate genome‐wide patterns of variation, we used low‐coverage sequencing to perform a region‐wide, whole‐genome analysis of fine‐scale population structure. We sequenced 306 individuals from 20 sampling locations in U.S. and Canadian waters, including the major spawning aggregations in the Gulf of Maine in addition to spawning aggregations from Georges Bank, southern New England, the eastern Scotian Shelf, and St. Pierre Bank. With genotype likelihoods estimated at almost 11 million loci, we found large differences in haplotype frequencies of previously described chromosomal inversions between Canadian and U.S. sampling locations and also among U.S. sampling locations. Our whole‐genome resolution also revealed novel outlier peaks, some of which showed significant genetic differentiation among sampling locations. Comparisons between allochronic winter‐ and spring‐spawning populations revealed highly elevated relative (FST) and absolute (dxy) genetic differentiation near genes involved in reproduction, particularly genes associated with the brain‐pituitary‐gonadal axis, which likely control timing of spawning, contributing to prezygotic isolation. We also found genetic differentiation associated with heat shock proteins and other genes of functional relevance, with complex patterns that may point to multifaceted selection pressures and local adaptation among spawning populations. We provide a high‐resolution picture of U.S. Atlantic cod population structure, revealing greater complexity than is currently recognized in management. Our genome‐scan approach likely underestimates the full suite of adaptive differentiation among sampling locations. Nevertheless, it should inform the revision of stock boundaries to preserve adaptive genetic diversity and evolutionary potential of cod populations.