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Avian species are in rapid decline worldwide, with 1 in 8 species facing extinction, and in North America shorebird species are declining at a higher proportion than other groups. The nearshore ecosystem in Maine (USA) supports several bird species that rely on intertidal and subtidal zones, including high densities of migratory shorebirds and wintering waterfowl. Additionally, Acadia National Park (ANP) includes some of the country's highest densities of declining populations of Purple Sandpipers (Calidris maritima) and state threatened Harlequin Ducks (Histrionicus histrionicus). We investigated whether the distribution of candidate umbrella species overlapped with the distribution of 5 waterfowl taxa (Common Eiders [Somateria mollissima], Long-tailed Ducks [Clangula hyemalis], Black Scoters [Melanitta americana], Bucephala spp., and Mallards [Anas platyrhynchos]), thereby examining whether conservation actions (e.g., conservation closures) taken to preserve these 2 species of high conservation concern might also benefit the larger taxonomic groups to which they belong, a concept known as umbrella species conservation. To answer this question, bird abundance surveys were conducted within ANP during 2021 and 2022, and detection and occupancy were compared among the focal groups using a hypothesis-driven model. The occupancy distributions of our 5 waterfowl taxa revealed that sites with the highest occupancy estimates for Common Eiders, Long-tailed Ducks, and Black Scoters included sites occupied by Purple Sandpipers and Harlequin Ducks. Bucephala spp. and Mallard occupancy, however, only weakly overlapped with our candidate umbrella detections, occurring in sites with the lowest and mid-range occupancy estimates. Thus, any positive effect of conservation closures based on these 2 species of concern might impact some, but not all, species we surveyed. Including more survey locations occupied by Purple Sandpipers and Harlequin Ducks would be necessary to see if this pattern is generalizable across the region. Our low sample size for umbrella species detections, however, also highlights the limited utility of using rare species as umbrellas. Received 12 August 2023. Accepted 2 March 2024. Key words: coastal ecosystem, Harlequin Duck, Purple Sandpiper, rockweed harvesting, single-species occupancy. (Spanish)-Las especies de aves estan en un declive rapido en todo el mundo, con 1 de cada 8 especies en riesgo de extincion y en Norteamerica las especies de aves costeras estan declinando a una mayor proporcion que otros grupos. El ecosistema litoral en Maine (EEUU) sostiene a varias especies de aves que dependen de zonas intermareal y submareales, incluyendo altas densidades de aves playeras migratorias y aves acuaticas invernales. Adicionalmente, Acadia National Park (ANP) incluye unas de las densidades mas altas del pais de las poblaciones en declive de correlimo Calidris maritima y de pato Histrionicus histrionicus, amenazados a nivel estatal. Estudiamos si la distribucion de especies sombrilla candidatas sobrelapaba con la distribucion de 5 taxa de aves acuaticas (eider Somateria mollissima, pato Clangula hyemalis, pato negro Melanitta americana, Bucephala spp. y pato Anas platyrhynchos), por tanto examinando si las acciones de conservacion (como cierres de conservacion) tomadas para preservar esas 2 especies en peligro critico tambien podrian beneficiar a los grupos taxonomicos mas amplios a los que pertenecen, un concepto conocido como conservacion de especies sombrilla. Para responder a esta pregunta, se realizaron reconocimientos de abundancia de aves en ANP durante el 2021 y el 2022, y se comparo la deteccion y la ocupacion entre grupos focales usando un modelo guiado por hipotesis. La distribucion de ocupacion de nuestras 5 taxa de aves acuaticas mostraron que los sitios con los mayores estimados de ocupacion para eider S. mollissima, pato C. hyemalis y pato negro Melanitta americana incluian sitios ocupados por correlimo C. maritima y pato H. histrionicus. Sin embargo, la ocupacion de Bucephala spp. y de pato A. platyrhynchos solo tuvo un debil sobrelapamiento con la deteccion de nuestras candidatas a especies sombrilla, en sitios con estimados de ocupacion de rango medio y bajo. Entonces, cualquier conclusion positiva del efecto de conservacion basada en estas 2 especies de interes puede tener algun impacto sobre algunas, pero no todas, las especies del reconocimiento. Seria necesario incluir mas localidades de reconocimiento ocupadas por correlimo Calidris maritima y pato H. histrionicus para ver si este patron es generalizable en toda la region. Nuestro bajo numero de reconocimientos para la deteccion de especies sombrilla, sin embargo, tambien recalca el uso limitado de usar especies raras como especies sombrilla. Palabras clave: correlimo Calidris maritima, cosecha de algas, ecosistemas costeros, ocupacion de una sola especie, pato Histrionicus histrionicus., During the Maine winter, the coastal areas of Acadia National Park (ANP) include some of the continental United States' highest densities of both Purple Sandpipers (Calidris maritima) and Harlequin Ducks [...]

Acid deposition from fossil fuel combustion caused calcium depletion in eastern North America during the 20th century, and calcium is a critical resource for birds during both the egg laying and nesting periods. The effects of acid deposition on animals have largely acted through trophic relationships, with reduced calcium availability in prey possibly being a limiting factor for forest songbirds. Following 21 years of experimental whole-watershed acidification at the Bear Brook Watershed in Maine, we investigated Ovenbird (Seiurus aurocapilla) territory size and potential prey (leaf litter arthropod) abundance, assemblage, and calcium concentration during one breeding season. We delineated and estimated the area of 8 Ovenbird territories in an acidified and a control watershed, but found that territory size did not differ between watersheds. However, while calcium concentrations of potential prey also did not differ between watersheds, territory size decreased as calcium concentrations of potential prey increased, regardless of watershed. Our results suggest that calcium limitation can be a determinant of territory size in some landscapes, and this provides further support to importance of the role of calcium in the lives of passerines. Received 17 June 2020. Accepted 1 October 2021. Key words: acid deposition, breeding ecology, calcium, nutrient limitation, trophic interactions. La deposicion de acido producto de la quema de combustibles fosiles causo perdidas dc calcio en el este de Norteamerica durante cl siglo veintc y el calcio es un recurso critico para las aves durante los periodos de puesta de huevos y anidacion. En su mayoria, los efectos de la deposicion de acido en animales han operado por medio de relaciones troficas, donde una reduccion en la disponibilidad de calcio en sus presas es posiblcmente un factor limitante para aves canoras de bosque. Siguiendo 21 afios de acidification experimental de toda la cuenca en la Bear Brook Watershed en Maine, investigamos el tamano del territorio y la abundancia, ensamble y concentracion de calcio de las presas potenciales (artropodos de la hojarasca) del chipe Seiurus aurocapilla durante una temporada reproductiva. Delineamos y estimamos el area de 8 territorios dc este chipe cn una cuenca acidificada y una cuenca control, pcro encontramos que el tamano del territorio no difiere entre estas. Sin embargo, aunque las concentraciones de calcio de sus presas potenciales tampoco difieren entre cuencas, el tamano de territorio decrccio mientras que la concentration de calcio de presas potenciales se incremento independientemente dc la cuenca. Nuestros resultados sugieren que la [imitation de calcio puede ser una determinantc de tamano de territorio en algunos paisajes y esto provee mayor soporte a la importancia del calcio en la vida de las paserinas. Palabras clave: calcio, deposition de acido. ecologia de la reproduccion. interacciones troficas. limitation de nutrientes., Effects of acid deposition from fossil fuel combustion on ecosystems came to the forefront of society's ecological consciousness in the latter half of the twentieth century (Lynch et al. 2000). [...]

Eco‐phylogeographic approaches to comparative population genetic analyses allow for the inclusion of intrinsic influences as drivers of intraspecific genetic structure. This insight into microevolutionary processes, including changes within a species or lineage, provides better mechanistic understanding of species‐specific interactions and enables predictions of evolutionary responses to environmental change. In this study, we used single nucleotide polymorphisms (SNPs) identified from reduced representation sequencing to compare neutral population structure, isolation by distance (IBD), genetic diversity and effective population size (Ne) across three closely related and co‐distributed saltmarsh sparrow species differing along a specialization gradient—Nelson's (Ammospiza nelsoni subvirgata), saltmarsh (A. caudacuta) and seaside sparrows (A. maritima maritima). Using an eco‐phylogeographic lens within a conservation management context, we tested predictions about species' degree of evolutionary history and ecological specialization to tidal marshes, habitat, current distribution and population status on population genetic metrics. Population structure differed among the species consistent with their current distribution and habitat factors, rather than degree of ecological specialization: seaside sparrows were panmictic, saltmarsh sparrows showed hierarchical structure and Nelson's sparrows were differentiated into multiple, genetically distinct populations. Neutral population genetic theory and demographic/evolutionary history predicted patterns of genetic diversity and Ne rather than degree of ecological specialization. Patterns of population variation and evolutionary distinctiveness (Shapely metric) suggest different conservation measures for long‐term persistence and evolutionary potential in each species. Our findings contribute to a broader understanding of the complex factors influencing genetic variation, beyond specialist‐generalist status and support the role of an eco‐phylogeographic approach in population and conservation genetics. [ABSTRACT FROM AUTHOR]

Organic acids produced by biota have been shown to accelerate the dissolution of minerals, possibly creating biosignatures in either reacting solutions or the solid materials. We tested aqueous alteration of serpentinite in three groups of solutions: inorganic acids, organic acids created through abiotic processes (termed "abiotic–organics"), and organic acids created through biotic processes (termed "biotic acids") over a range of temperatures relevant to conditions on Mars and Europa. A total of 48 batch reactor experiments were carried out at 0 °C, 22 °C, and 62 °C in 16 different acids at pH 2.6 over 28 days. Additional experiments were conducted in sulfuric acid solutions to assess aqueous alteration in sulfate-rich environments. These results show that biotic acids accelerate serpentinite dissolution compared to the control inorganic acid, whereas abiotic–organic acids have little or no effect. Sulfuric acid enhances serpentinite dissolution over nitric acid. Secondary precipitates found in the presence of biotic acids were consistently enhanced in Mn, Ti, and W. We propose that these preferentially released elements and secondary minerals may be potential biosignatures. We also show that the release of the rock-forming elements Mg and Si is correlated with stability constants for the metal–acid aqueous complex, providing a possible mechanistic interpretation of the observed results. [ABSTRACT FROM AUTHOR]

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 (Ammospiza caudacuta), 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 to 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 (A. nelsoni) 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. [ABSTRACT FROM AUTHOR]

The high attrition rate among science, technology, engineering, and mathematics (STEM) majors has long been an area of concern for institutions and educational researchers. The transition from introductory to advanced courses has been identified as a particularly "leaky" point along the STEM pipeline, and students who struggle early in an introductory STEM course are predominantly at risk. Peer-tutoring programs offered to all students in a course have been widely found to help STEM students during this critical transition, but hiring a sufficient number of tutors may not be an option for some institutions. As an alternative, this study examines the viability of an optional peer-tutoring program offered to students who are struggling in a large-enrollment, introductory biology course. Struggling students who regularly attended peer tutoring increased exam performance, expert-like perceptions of biology, and course persistence relative to their struggling peers who were not attending the peer-tutoring sessions. The results of this study provide information to instructors who want to design targeted academic assistance for students who are struggling in introductory courses.

Copyright of Ornithology (Oxford University Press) is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) breeds in coastal marshes of the mid-Atlantic United States. During the nonbreeding season, these marshes are occupied by this subspecies and the two interior-breeding subspecies M. g. georgiana and M. g. ericrypta (collectively, interior Swamp Sparrows). From September to May, 2005-2006 and 2007-2008, we surveyed marshes in which nigrescens breeds; >90% of these birds had been color-banded by the end of the previous breeding season. This allowed us to determine the nonbreeding occupancy of the breeding site by individuals that bred locally, Coastal Plain Swamp Sparrows that did not breed there, and interior Swamp Sparrows. Locally breeding birds disappeared from the breeding site by mid-October, although nonlocal nigrescens occupied it from October to late November. Locally breeding birds reappeared in April without any pulse of migration of nigrescens. Interior-breeding sparrows were abundant in the autumn and appeared in smaller numbers later in the nonbreeding season. The seasonal pattern of nigrescens was similar in both years, and its departure and arrival dates appear to coincide with changes in the frequency of freezing temperatures. The temporal pattern of interior Swamp Sparrows in the two years was more varied. Finally, during the autumn peak of Swamp Sparrow migration, the subspecies tended strongly to segregate in subspecies-specific flocks, suggesting that Swamp Sparrows preferentially interact with morphologically similar birds, a behavior which may have implications for divergence in species recognition mechanisms and speciation. Key words: migration, subspecies, Melospiza georgiana, tidal marsh, social segregation, geographic variation, species recognition, Swamp Sparrow. Melospiza georgiana nigrescens se reproduce en marismas de los estados localizados en la costa central del Atlantico de Norteamerica. Durante el periodo no reproductivo, estas marismas son ocupadas por esta subespecie y por otras dos subespecies del interior, M. g. georgiana y M. g. ericrypta. Desde septiembre a mayo de 2005-2006 y 2007-2008, realizamos conteos en marismas en que se reproduce la subespecie nigrescens. Hasta el fin del periodo reproductivo anterior, mas del 90% de estas aves habian sido marcadas con anillos de colores. Esto nos permitio determinar la ocupacion durante el periodo no reproductivo del sitio de cria por parte de individuos que se reproducen localmente, de individuos de M. g. nigrescens que no se reproducen en esa localidad y por parte de las otras dos subespecies del interior. Los individuos que se reproducen localmente desaparecieron del sitio de cria a mediados de octubre, a pesar de que individuos no locales de la subespecie nigrescens ocuparon el sitio desde octubre hasta fines de noviembre. Los individuos que se reproducen en la localidad reaparecieron en abril, sin un pulso migratorio de la subespecie nigrescens. Las subespecies que se reproducen en el interior fueron abundantes durante el otono y aparecieron en numeros menores durante las etapas mas tardias de la epoca de cria. El patron estacional de la subespecie nigrescens fue similar en ambos anos, y sus fechas de partida y llegada parecieron coincidir con cambios en la frecuencia con que se registran temperaturas bajo cero. El patron temporal de las subespecies del interior durante los dos anos fue mas variado. Finalmente, durante el periodo de mayor actividad migratoria del otono, las subespecies tendieron a agruparse en bandadas especificas para cada subespecie, lo que sugiere que estas especies de pinzones prefieren interactuar con individuos morfologicamente mas similares entre si que con individuos de otras subespecies, un comportamiento que puede tener implicaciones importantes para la divergencia y mecanismos de reconocimiento entre especies y para los procesos de especiacion. DOI: 10.1525/cond.2010.080060

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 (R2 = 0.39) relationship between genomic differentiation (FST) and phenotypic differentiation (PST) for loci and traits putatively under selection. This quantitative relationship between PST and FST 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 PST and FST 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. [ABSTRACT FROM AUTHOR]

Humans are dominant global drivers of ecological and evolutionary change, rearranging ecosystems and natural selection. In the present article, we show increasing evidence that human activity also plays a disproportionate role in shaping the eco-evolutionary potential of systems—the likelihood of ecological change generating evolutionary change and vice versa. We suggest that the net outcome of human influences on trait change, ecology, and the feedback loops that link them will often (but not always) be to increase eco-evolutionary potential, with important consequences for stability and resilience of populations, communities, and ecosystems. We also integrate existing ecological and evolutionary metrics to predict and manage the eco-evolutionary dynamics of human-affected systems. To support this framework, we use a simple eco–evo feedback model to show that factors affecting eco-evolutionary potential are major determinants of eco-evolutionary dynamics. Our framework suggests that proper management of anthropogenic effects requires a science of human effects on eco-evolutionary potential. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Salt marshes of the northeastern United States are dynamic landscapes where the tidal flooding regime creates patterns of plant zonation based on differences in elevation, salinity, and local hydrology. These patterns of zonation can change quickly due to both natural and anthropogenic stressors, making tidal marshes vulnerable to degradation and loss. We compared several remote sensing techniques to develop a tool that accurately maps high- and low-marsh zonation to use in management and conservation planning for this ecosystem in the northeast USA. We found that random forests (RF) outperformed other classifier tools when applied to the most recent National Agricultural Imagery Program (NAIP) imagery, NAIP derivatives, and elevation data between coastal Maine and Virginia, USA. We then used RF methods to classify plant zonation within a 500-m buffer around coastal marsh delineated in the National Wetland Inventory. We found mean classification accuracies of 94% for high marsh, 76% for low marsh zones, and 90% overall map accuracy. The detailed output is a 3-m resolution continuous map of tidal marsh vegetation communities and cover classes that can be used in habitat modeling of marsh-obligate species or to monitor changes in marsh plant communities over time. [ABSTRACT FROM AUTHOR]