Microsatellite loci in non-coding regions of nuclear DNA provide an important tool for genetic diversity research, particularly when comparing relatedness between individuals. While microsatellites have been developed for several species within the Blackbird family (Icteridae), no species-specific microsatellite primers for genetic analysis of Bobolinks (Dolichonyx oryzivorus) exist. Like many grassland songbirds, Bobolink populations are in decline, and accessible genetic analysis tools are therefore critical for understanding population dynamics. This paper introduces ten new, polymorphic microsatellite loci, at least eight of which should provide a reliable tool for the future study and monitoring of Bobolink genetics. These hypervariable and thus highly informative loci were amplified in 152 adult individuals from a well-studied population in Shelburne, Vermont, USA.

The intimate associations between plants and microbes that develop in rhizosphere soils may alter the sensitivity of bacterial communities to environmental filters during the process of community assembly. We compared the sensitivity of rhizosphere and bulk soil communities to ecological variables in several New England salt marshes dominated by Spartina alterniflora (Smooth Cordgrass), characterizing community variation based on linear combinations of 16S rDNA fragments representing bacterial taxonomic units. Rhizosphere microbes showed significantly greater sensitivity to plant biomass and pH, perhaps because of their relationships with the quality of plant exudates and availability of nutrients, respectively, while bulk microbes showed significantly greater sensitivity to elevation and redox potential, perhaps through waterlogging and an absence of plants oxygenating the soil.

The high elevation salt marsh plant Spartina patens can potentially cope with accelerated sea level rise by migrating inland, but the ability to do so may differ among plant ecotypes. We compared performance among ecotypes collected from three different sites within mesocosms in which we manipulated soil type, plant litter and salinity. Half of our treatment levels simulated conditions plants would encounter when expanding into terrestrial environments (i.e., upland soil, litter present and low salinity); the other half expansion into tidal creeks (i.e., marsh soil, litter absent, and high salinity). Plant litter and salinity did not significantly affect aboveground biomass or rhizome growth and only affected flowering in a three-way interaction with site. However, all three parameters were significantly affected by soil conditions and the site × soil interaction. Upland soil conditions reduced aboveground biomass, rhizome growth and flowering, as compared to marsh soil conditions, for ecotypes from some sites but not others. When just comparing plant performance in the upland soil treatment, ecotypes from some collection sites did better than others. One plausible explanation for this ecotypic variation is pre-adaptation to differences we found in organic matter content among our collection sites, with the ecotype collected from the site with the lowest organic matter content generally being least impacted by upland soil conditions. Our results indicate that S. patens ecotypes can vary in their capacity to successfully expand into uplands, and thus we suggest prioritizing conservation of such ecotypes, as well as their use in restoration efforts. Consideration of ecotypic variation might also prove useful in deciding where to focus conservation efforts for marsh migration.

Genotypic diversity has the potential to function in a similar manner to species diversity, particularly in ecosystems dominated by a single foundational plant, and may promote stability in the face of disturbance. However, it has primarily been documented only in terrestrial species or in seagrasses. We conducted three separate experiments in which we compared plant production between monocultures and polycultures of the widely distributed salt marsh macrophyte Spartina alterniflora, exposed to increased levels of stress from competition, herbivory, and tidal inundation (simulating the effects of sea-level rise). Increased levels of disturbance reduced aboveground growth of monocultures in all three experiments, but greater clonal diversity offset the negative effects of increased levels of all the stressors in polycultures. Our results contribute to a growing body of literature demonstrating that genotypic diversity of a foundational species can function analogously to species diversity. They also highlight the potential importance of high levels of genotypic diversity in this species in determining the response to anthropogenic disturbances and in management or restoration efforts.

To better understand the dynamics of avian populations and their role in population trends, we require an in-depth understanding of the factors influencing the survival of adults and juveniles. However, assessing survival in juveniles is often challenging, especially in small, migratory species where individuals typically disperse from the study area and are not available for recapture in subsequent years. Bobolinks (Dolichonyx oryzivorus) are a long-distance migrant that exhibits natal philopatry in at least one population, allowing for more comprehensive juvenile survival analyses than in many other long-distance avian migrants. Using a 17-yr dataset from two sites representing a Vermont population of Bobolinks, we used Program MARK to assess factors influencing apparent juvenile survival, including factors related to nesting timing, nest attempt number, the philopatric behaviors of relatives, body mass, brood size, and agricultural management scheme. Our top models indicated that nest attempt number and whether or not a nest mate also survived and returned to breed locally were important factors explaining variation in apparent survival in juvenile Bobolinks. Specifically, juveniles from first nest attempts that fledged earlier in the season, with siblings that did not survive and return to breed locally, showed higher apparent survival. Factors such as site and the philopatric behavior of females associated with nests also appeared in top-ranking models, while factors such as body mass and brood size did not. These results indicate the importance of providing high-quality breeding habitat to birds early in the season when juvenile survival is greatest and indicate that individuals may be utilizing inbreeding avoidance strategies. These results provide new insight into the ecological and agricultural management factors influencing survival in migratory species that use managed habitats and underscore the importance of integrating juvenile survival data into current management schemes to better support this and other declining species.

Atlantic white-sided dolphins (Lagenorhynchus acutus) are highly social odontocetes with a poorly understood tendency to mass strand. With limited capacity to study social ecology in the open ocean, mass strandings provide an opportunity to improve our understanding of group structure. Our study of 32 mass stranding events that occurred on Cape Cod, Massachusetts, between 1999 and 2009 identifies aspects of social ecology that vary across the year. A greater number of mass stranding events occurred outside of the breeding season and there was evidence of age-structuring during the breeding season. We find generally low average intragroup pairwise relatedness assessed across eight microsatellite loci in a subset of 16 mass stranding events. Mass stranded groups do not show higher than expected relatedness when compared to a baseline estimate derived from single-stranded individuals. Overall, our integration of genetic estimates of relatedness with data on sex and maturity-class from stranded specimens suggests that Atlantic white-sided dolphins fall near the more fluid end of the continuum from short-term, highly fluid social associations to long-term, stable groups represented among the odontocetes. Despite their tendency to mass strand, stable, kin-based associations are not a defining feature of social group structure in this species.

Since the mid-1980s, our understanding of avian reproductive strategies has shifted as new molecular technologies have revealed how common promiscuity is in many monogamous avian species. However, the prevalence and importance of extra-pair paternity in polygynous species is less well studied. We used microsatellite loci from related icterid species to identify the extra-pair paternity rate in a polygynous population of Bobolinks (Dolichonyx oryzivorus) that bred in the Champlain Valley of Vermont from 2002 to 2018. We assigned paternity for 120 nestlings and found that 42% of nestlings were sired by extra-pair males. These results highlight the importance of extra-pair paternity in the reproductive behavior of Bobolinks that breed in agricultural habitats.

The Prairie Pothole Region (PPR) of North America has experienced extreme changes in wetland habitat due to proliferation of invasive plants. Typha × glauca is a highly competitive hybrid between native T . latifolia and non-native T . angustifolia , and it is likely the predominant taxon in PPR wetlands. Genetics-based studies are limited, and distributions are poorly known for the first-generation (F 1 ) hybrid and advanced-generation hybrids from F 1 mating. Information pertaining to the distribution of T . × glauca could benefit efforts to understand the mechanisms of its spread and to develop management strategies to limit hybrid expansion and preserve progenitors. We used microsatellite markers of field-collected tissue samples from 131 wetlands spread over approximately 350,000 km 2 in the PPR to assess the distribution of hybrid T. × glauca relative to its parental species and to examine the prevalence of F 1 hybrids and advanced-generation hybrids. Typha × glauca was found in over 80% of wetlands throughout the PPR, compared to 26 and 18% of wetlands with T . latifolia and T . angustifolia , respectively. Advanced-generation hybrids were more common than F 1 hybrids, suggesting that hybridization is not a recent phenomenon. Hybrids were significantly taller than T . latifolia , indicating heterosis. Only 7% of sampled individual genets were pure T. latifolia . These results suggest that T. × glauca is pervasive throughout the PPR and may spread independently of both parents. In addition, limited prevalence of native T. latifolia indicates the need for active management to preserve the species.

Heritability and evolvability estimates of adult traits from free-living bird populations can be used to gauge the ability of populations to respond to selection, but are rare due to difficulties in gathering detailed pedigree information. The capacity to respond to selection is particularly important for species occupying managed habitats such as agricultural grasslands because of the potential for humans to accidentally influence traits. We calculated heritability and evolvability of six morphological traits in a population of Savannah Sparrows (Passerculus sandwichensis) breeding in a large agricultural landscape. We used microsatellite analysis to determine a genetic pedigree, revealing a high level of extra-pair paternity (63%) within a relatively philopatric population. For the entire population, heritabilities varied from low to high (bill width: 0.160±0.182 to tarsus length: 0.651±0.155), while evolvabilities were low across all traits (wing length: 0.035±0.013 to body mass: 0.066±0.106). Our results indicate that any directional selection from agricultural management practices will produce negligible changes in basic morphometrics of Savannah sparrow populations occupying the Champlain Valley of Vermont, USA.

Typha is an iconic wetland plant found worldwide. Hybridization and anthropogenic disturbances have resulted in large increases in Typha abundance in wetland ecosystems throughout North America at a cost to native floral and faunal biodiversity. As demonstrated by three regional case studies, Typha is capable of rapidly colonizing habitats and forming monodominant vegetation stands due to traits such as robust size, rapid growth rate, and rhizomatic expansion. Increased nutrient inputs into wetlands and altered hydrologic regimes are among the principal anthropogenic drivers of Typha invasion. Typha is associated with a wide range of negative ecological impacts to wetland and agricultural systems, but also is linked with a variety of ecosystem services such as bioremediation and provisioning of biomass, as well as an assortment of traditional cultural uses. Numerous physical, chemical, and hydrologic control methods are used to manage invasive Typha, but results are inconsistent and multiple methods and repeated treatments often are required. While this review focuses on invasive Typha in North America, the literature cited comes from research on Typha and other invasive species from around the world. As such, many of the underlying concepts in this review are relevant to invasive species in other wetland ecosystems worldwide.

The aim of this project was to compare the phenotypic responses of global populations of Lythrum salicaria in cold/dry and hot/humid environments to determine if phenotypic plasticity varied between the native and invasive ranges, and secondarily if this variation was linked to genetic diversity. Common garden studies were conducted in Třeboň, Czech Republic, and Lafayette, Louisiana, USA (cold/dry vs. hot/humid garden, respectively), using populations from latitudinal gradients in Eurasia and North America. Lythrum salicaria seeds collected from the same maternal plants across these latitudinal gradients were germinated and grown in Třeboň and Lafayette. Tissue masses (above-, below-ground, inflorescence and total) of these individuals were assessed at the end of each growing season (2006–2008). Worldwide field measurements of L. salicaria height were made by volunteers from 2004–2016. Biomass and height data were analyzed using the General Linear Model framework and multivariate techniques. Molecular markers (amplified fragment length polymorphisms) of individuals used in the common garden study were analyzed using traditional genetic diversity metrics and Bayesian clustering algorithms in STRUCTURE. Reaction norms were developed from differences in maternal plant responses in Třeboň versus Lafayette. In the common garden studies, stem/leaf, root and total biomass generally were highest for individuals grown from seeds collected in the southern part of the range in the cold garden, particularly by the third year of the study. In contrast, inflorescence biomass in the cold garden was higher by the third year in individuals from mid-latitude populations. As measured by volunteers, plants were taller in Eurasia than in North America moving from north to south with the pattern switching southward of 40°N latitude. Genetic diversity was similar between native and non-native invasive populations regardless of geographical origin of the seed and was not significantly different in the GLM Select model (p > 0.05). Reaction norm slopes showed that Eurasia had larger values than North America for reaction norms for above-ground and total biomass. Plants from the seeds of mother plants from Turkey had wide variation in total biomass when grown in Třeboň versus Lafayette; this variation in response within certain populations may have contributed to the lack of population-level differences in plasticity. These results indicate no loss of genetic diversity for L. salicaria during its North American invasion, nor reduction in plastic tissue allocation responses to a varying environment, which may help explain some of its invasive qualities and which could be of adaptive value under changing future environments.

Abstract Although microbial communities have been shown to vary among plant genotypes in a number of experiments in terrestrial ecosystems, relatively little is known about this relationship under natural conditions and outside of select model systems. We reasoned that a salt marsh ecosystem, which is characterized by twice‐daily flooding by tides, would serve as a particularly conservative test of the strength of plant–microbial associations, given the high degree of abiotic regulation of microbial community assembly resulting from alternating periods of inundation and exposure. Within a salt marsh in the northeastern United States, we characterized genotypes of the foundational plant Spartina alterniflora using microsatellite markers, and bacterial metagenomes within marsh soil based on pyrosequencing. We found significant differences in bacterial community composition and diversity between bulk and rhizosphere soil, and that the structure of rhizosphere communities varied depending on the growth form of, and genetic variation within, the foundational plant S. alterniflora. Our results indicate that there are strong plant–microbial associations within a natural salt marsh, thereby contributing to a growing body of evidence for a relationship between plant genotypes and microbial communities from terrestrial ecosystems and suggest that principles of community genetics apply to this wetland type.

We explored the nature and impact of competitive interactions between the salt marsh foundational plant Spartina alterniflora and invasive Phragmites australis in New England under varying levels of anthropogenic influence from nutrient loading and temperature warming. Plants were grown with and without competition in mesocosms over a four-month growing season. Mesocosms were split evenly among three levels of nutrient additions and two temperatures varying by an average of ~3° C, manipulated using small greenhouses. We measured aboveground productivity as total biomass, numbers of new stems, and mean stem height. Nutrient enrichment increased all growth parameters, while competition generally reduced aboveground biomass and the production of new stems in both species. Most importantly, smooth cordgrass suffered no negative consequences of competition when no nutrients were added and temperature was elevated. The results of this study suggest that minimizing nutrient loading into coastal marshes could be an important factor in slowing the spread of common reed into the low marsh zone of New England salt marshes as global temperatures continue to warm.

There is growing evidence for a tight linkage between the structure and function of microbial communities and for the importance of this relationship in ecosystem responses to disturbances such as sea-level rise (SLR). While the role of plants in determining the capacity of salt marshes to keep pace with SLR through sediment accretion has received considerable attention, the role of microbes in offsetting these gains via decomposition is less understood.

Knowledge of which cues attract birds back to natal areas is important for conservation because the cues could be manipulated to attract breeders to source habitat or discourage breeders from settling in sink habitat. We examined the influence of intrinsic and extrinsic variables on natal philopatry using two metrics, short-distance natal dispersal and the probability of philopatry to the natal field, in two obligate-grassland bird species breeding in an agricultural landscape: the bobolink, Dolichonyx oryzivorus, and the Savannah sparrow, Passerculus sandwichensis. During 2002-2014, we detected 90 locally hatched Savannah sparrows and 129 locally hatched bobolinks breeding as adults near their places of origin (mean +/- SD dispersal distances: Savannah sparrows: 917 +/- 851 m; bobolinks: 1251 +/- 839 m). For both species, the location of the field on which they bred relative to fields where annual productivity was greater than replacement best explained variation in natal dispersal distance. The probability a Savannah sparrow was philopatric to its natal field increased if it fledged later in the season, while this probability decreased if there was an opposite-sex parent or sibling present on the natal field, or the field was under a late-hay management scheme. None of the variables considered explained variation in bobolink natal philopatry. Natal philopatry and short-distance natal dispersal in these species appear to be influenced by factors that are difficult to manage; however, land managers should attempt to keep management consistent across time to reduce misinformation in dispersal cues. (C) 2016 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

We evaluated the importance of Allee effects, defined as declines in individual fitness with low population density or size, in the spread of invasive Phragmites australis occupying a small riverine system in Maine. We also investigated the potential of hydrodynamic drivers of propagule dispersal to alleviate Allee effects. We used molecular markers to assess genotypic richness and its relationship with patch vigor, modeled as patch expansion rate, stem density, and stem height. We hypothesized that an Allee effect would create a positive relationship between genotypic richness and patch vigor, which would be bolstered under specific environmental conditions, specifically shoreline development and nutrient enrichment. Contrary to predictions, genotypic richness and patch vigor were unrelated, as were genotypic richness and seed viability. Genotypic richness varied positively with increasing low-level (i.e., residential) development, but only in the presence of vacant substrate, specifically barren sand. Genotypic richness was also positively correlated with the proximity of open freshwater. Patch vigor was driven by a combination of distance to the river mouth and available ammonium in the soil. Overall, we found relatively high genotypic richness (mean = 0.464), which suggests that the Phragmites invasion of the Saco River estuary may have already advanced beyond any early Allee effects, if they occurred in this riverine system. (C) 2016 Elsevier B.V. All rights reserved.

Ecologists have a growing appreciation for the influence of intraspecific, or genotypic, diversity on ecosystem functioning in species depauperate systems such as salt marshes, with intraspecific interactions serving as one potential driver of such diversity. We examined the role of intraspecific interactions, both competitive and facilitative, in structuring populations of Spartina alterniflora, a foundational salt marsh plant known to influence community structure and function throughout its native distribution in eastern North America. We conducted a transplantation experiment at a created site in southwestern Louisiana, USA, by growing five S. alterniflora genotypes, or clones, for two years in all possible combinations, and monitored their interactions using morphological measurements and molecular marker genotyping. Using stem densities as a proxy for above-ground biomass, we found support for our hypothesis that interactions have a mutually limiting effect on growth, although we were unable to find statistical support for competitive asymmetries between specific clone pairs, which would have explained earlier observations of declining genotypic diversity in aging marshes. Using proportions of stems flowering as a proxy for reproductive effort, we also found support for our hypothesis that interactions can have a stimulatory effect on flowering, which could promote genotypic diversity through the recruitment of out crossed seedlings in a species known for severe inbreeding depression. Reproductive interactions were at times mutually inhibitory or stimulatory, as evidenced by positive correlations of flowering responses between clones. To our knowledge, ours is one of the first studies to evaluate the outcome of one-on-one interactions among genotypes of a foundational clonal plant. (C) 2016 Elsevier GmbH. All rights reserved.

Mangroves migrate northward in Florida and colonize marshes historically dominated by salt marsh species. In theory, this migration should be facilitated by greater numbers of propagules stemming from increased reproductive activity and greater genetic variability caused by outcrossing. We aimed to determine if stand reproduction and % outcrossing were affected by cold stress (stress increases with latitude), anthropogenic stress (human population density as a proxy), and years since a major hurricane. Further, we wished to determine if mutation rate varied with the stressors and if that affected stand reproduction. Both coasts of Florida from the southern Florida Keys to Tampa Bay on the Gulf of Mexico coast, and Merritt Island on the Atlantic coast. We conducted field surveys of frequency of reproducing trees (104,211 trees surveyed in 102 forested stands), incidence of trees showing albinism in propagules, and% outcrossing estimated from the ratio of albino:normal propagules. Structural equation modeling ( SEM ) was used to test a conceptual model that served as a multivariate hypothesis. Reproductive frequencies varied by site and increased with latitude although more strongly on the Gulf coast. Our SEM results indicate that outcrossing increases in this predominately selfing species under conditions of cold and anthropogenic stress, and that this increases reproductive output in the population. Further, we find that increased mutation rates suppress stand reproductive output but there is no significant relationship between outcrossing and mutation rate. Tree size responded to stressors but did not affect stand reproduction. Reproduction increased with years since major hurricane. Potential for colonization of northern Florida salt marshes by mangroves is enhanced by increased reproductive rates that provides more propagules and outcrossing that should enhance genetic variation thereby promoting adaptation to novel environmental conditions. Natural (cold) stress reduced mutation rate and increased stand reproductive output but anthropogenic stress did the opposite.

To maximize fitness, breeding adults may respond to environmental processes by adjusting their progeny's sex ratios. R. A. Fisher in 1930 hypothesized that frequency-dependent selection would result in equal investment in sons and daughters over the long term, yielding a balanced sex ratio if the costs of raising a son and daughter are equal. Diverse hypotheses have tried to explain population and brood-by-brood deviations from this mean as well as annual variation by focusing on adult sex ratios, resources, abiotic conditions, and female and male quality. We collected data in 20022010 to explore population-level variation in nestling sex ratios in 2 migratory grassland songbird species: the Bobolink (Dolichonyx oryzivorus) and Savannah Sparrow (Passerculus sandwichensis). These species differ in migratory strategy (long-distance vs. short-distance), and morphological dimorphism. Fisher's hypothesis was rejected for Savannah Sparrows (n = 684 nestlings; 39% male) but not rejected for Bobolinks (n=390 nestlings; 53.8% male). No relationship was found between nestling and adult sex ratios measured in the same year. In descriptive analyses at the brood level, male and female body size and age, and ecological conditions (temperature and precipitation) failed to predict nestling sex ratios. Although male nestlings were heavier than female nestlings and resource availability changed through the season, these factors did not influence sex ratios relative to female body size or seasonality. For Savannah Sparrows, larger broods tended to be male-biased. While we were otherwise not able to explain deviation in offspring sex ratio for Savannah Sparrows, our results suggest that the ecological and evolutionary pressures that affect sex ratios may be both species- and population-specific.

The effective control of invasive mammals, because of their potentially high dispersive capacity, demands an understanding of spatial patterns of gene flow leading to the designation of population units for systematic eradication. Nutria, or coypu (Myocastor coypus), are large, semi-aquatic rodents, originally exported from their native South America for the value of their fur, and are now considered pests on many continents due to overgrazing of wetlands. This study was aimed at assessing the potential for establishing eradication units for the control of nutria in a severely impacted region of the US, southern Louisiana, using nine microsatellite loci, and systematic sampling from each of eight major watershed basins. Unexpectedly high levels of genetic diversity were revealed in comparison to native populations both in terms of numbers of alleles and observed heterozygosities, suggesting that multiple source populations may have originally contributed to the establishment of the Louisiana fur trade, which have subsequently become intermingled. Genetic differentiation among watersheds was nearly undetectable, as evidenced by a very small, albeit significant overall F ST value of 0.0059. Interestingly, one of the Bayesian clustering algorithms used in this study identified 11 populations that may represent a fading remnant of the original source populations, although these clusters were not supported by a coherent pattern of geography. Unfortunately, these findings suggest that neither the establishment of locally manageable eradication units, nor the development of biological control agents known for their close association with a single source population will be effective in the control of Louisiana nutria.