bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of microbial mats on travertine precipitation in active hydrothermal systems (Central Italy)
Authors: Della Porta Giovanna , Hoppert Michael , Hallmann Christine , Schneider Dominik , Reitner Joachim 
Published: May 2021

AbstractThe study of hydrothermal travertines contributes to the understanding of the interaction between physico‐chemical processes and microbial mats in carbonate precipitation. Three active travertine sites were investigated in Central Italy to characterise the types of carbonate precipitates and the associated microbial mats at varying physico‐chemical parameters. Carbonate precipitated fabrics at the decimetre to millimetre‐scale and microbial mat composition vary with decreasing water temperature: (a) at relatively higher temperature (55–44°C) calcite and aragonite crystals precipitate on microbial mats of Chloroflexi and sulphur‐oxidizing microbes forming filamentous streamer fabrics with sparse cyanobacteria, (b) at intermediate temperature (44–40°C), rafts, coated gas bubbles and dendrites are associated with Spirulina cyanobacteria and other filamentous and rod‐shaped cyanobacteria, (c) low temperature (34–33°C) laminated crusts and oncoids forming in a terraced slope system are associated with diverse Oscillatoriales and Nostocales filamentous cyanobacteria, Spirulina and diatoms. At the microscale, carbonate precipitates are similar in the three sites consisting of prismatic calcite crystals organised in radial rosettes or fibrous aragonite spherulites (40–300 µm in diameter), overlying or embedded in Extracellular Polymeric Substances. Clotted peloidal micrite dominates at temperatures <40°C, also encrusting filamentous microbes. Carbonates are associated with gypsum crystals; extracellular polymeric substances are enriched in silicon, aluminium, magnesium, calcium, phosphorous and sulphur; authigenic aluminium‐silicates form aggregates on Extracellular Polymeric Substances. This study confirms that microbial communities in hydrothermal settings vary as a function of water temperature. Carbonate precipitates at the microscale are similar in the three settings, despite different microbial communities, suggesting that travertine precipitation, driven by carbon dioxide degassing, is influenced by biofilm extracellular polymeric substances acting as a substrate for crystal nucleation (Extracellular Polymeric Substances‐mediated mineralization) and affecting the resultant fabric types, independently from specific microbial community composition and metabolism.
Understanding evolutionary and ecological dynamics using a continuum limit
Authors: Czuppon Peter , Traulsen Arne 
Published: May 2021

AbstractContinuum limits in the form of stochastic differential equations are typically used in theoretical population genetics to account for genetic drift or more generally, inherent randomness of the model. In evolutionary game theory and theoretical ecology, however, this method is used less frequently to study demographic stochasticity. Here, we review the use of continuum limits in ecology and evolution. Starting with an individual‐based model, we derive a large population size limit, a (stochastic) differential equation which is called continuum limit. By example of the Wright–Fisher diffusion, we outline how to compute the stationary distribution, the fixation probability of a certain type, and the mean extinction time using the continuum limit. In the context of the logistic growth equation, we approximate the quasi‐stationary distribution in a finite population.
Adaptive population structure shifts in invasive parasitic mites, Varroa destructor
Authors: Moro Arrigo , Blacquière Tjeerd , Dahle Bjørn , Dietemann Vincent , Le Conte Yves , Locke Barbara , Neumann Peter , Beaurepaire Alexis 
Published: May 2021

AbstractComparative studies of genetic diversity and population structure can shed light on the ecological and evolutionary factors governing host–parasite interactions. Even though invasive parasites are considered of major biological importance, little is known about their adaptative potential when infesting the new hosts. Here, the genetic diversification of Varroa destructor, a novel parasite of Apis mellifera originating from Asia, was investigated using population genetics to determine how the genetic structure of the parasite changed in distinct European populations of its new host. To do so, mites infesting two categories of hosts in four European regions were compared: (a) adapted hosts surviving through means of natural selection, thereby expected to impose strong selective pressure on the mites, and (b) treated host populations, surviving mite infestations because acaricides are applied, therefore characterized by a relaxed selection imposed by the host on the mites. Significant genetic divergence was found across regions, partially reflecting the invasion pattern of V. destructor throughout Europe and indicating local adaptation of the mite to the host populations. Additionally, varying degrees of genotypic changes were found between mites from adapted and treated colonies. Altogether, these results indicate that V. destructor managed to overcome the genetic bottlenecks following its introduction in Europe and that host‐mediated selection fostered changes in the genetic structure of this mite at diverse geographic scales. These findings highlight the potential of parasites to adapt to their local host populations and confirm that adaptations developed within coevolutionary dynamics are a major determinant of population genetic changes.
Understanding the impact of correlation within pair‐bonds on Cormack–Jolly–Seber models
Authors: Draghici Alexandru M. , Challenger Wendell O. , Bonner Simon J. 
Published: May 2021

Abstract

The Cormack–Jolly–Seber (CJS) model and its extensions have been widely applied to the study of animal survival rates in open populations. The model assumes that individuals within the population of interest have independent fates. It is, however, highly unlikely that a pair of animals which have formed a long‐term pairing have dissociated fates.

We examine a model extension which allows animals who have formed a pair‐bond to have correlated survival and recapture fates. Using the proposed extension to generate data, we conduct a simulation study exploring the impact that correlated fate data has on inference from the CJS model. We compute Monte Carlo estimates for the bias, range, and standard errors of the parameters of the CJS model for data with varying degrees of survival correlation between mates. Furthermore, we study the likelihood ratio test of sex effects within the CJS model by simulating densities of the deviance. Finally, we estimate the variance inflation factor for CJS models that incorporate sex‐specific heterogeneity.

Our study shows that correlated fates between mated animals may result in underestimated standard errors for parsimonious models, significantly deflated likelihood ratio test statistics, and underestimated values of for models taking sex‐specific effects into account.

Underestimated standard errors can result in lowered coverage of confidence intervals. Moreover, deflated test statistics will provide overly conservative test results. Finally, underestimated variance inflation factors can lead researchers to make incorrect conclusions about the level of extra‐binomial variation present in their data.
Head and mandible shapes are highly integrated yet represent two distinct modules within and among worker subcastes of the ant genus Pheidole
Authors: Casadei‐Ferreira Alexandre , Friedman Nicholas R. , Economo Evan P. , Pie Marcio R. , Feitosa Rodrigo M. 
Published: May 2021

AbstractAnts use their mandibles for a wide variety of tasks related to substrate manipulation, brood transport, food processing, and colony defense. Due to constraints involved in colony upkeep, ants evolved a remarkable diversity of mandibular forms, often related to specific roles such as specialized hunting and seed milling. Considering these varied functional demands, we focused on understanding how the mandible and head shape vary within and between Pheidole subcastes. Using x‐ray microtomography and 3D geometric morphometrics, we tested whether these structures are integrated and modular, and how ecological predictors influenced these features. Our results showed that mandible and head shape of majors and minor workers tend to vary from robust to slender, with some more complex changes related to the mandibular base. Additionally, we found that head and mandible shapes are characterized by a high degree of integration, but with little correlation with feeding and nesting habits. Our results suggest that a combination of structural (allometric) constraints and the behavioral flexibility conferred by subcaste dimorphism might largely buffer selective pressures that would otherwise lead to a fine‐tuning between ecological conditions and morphological adaptation.
Rivers, not refugia, drove diversification in arboreal, sub‐Saharan African snakes
Authors: Allen Kaitlin E. , Greenbaum Eli , Hime Paul M. , Tapondjou N. Walter P. , Sterkhova Viktoria V. , Kusamba Chifundera , Rödel Mark‐Oliver , Penner Johannes , Peterson A. Townsend , Brown Rafe M. 
Published: May 2021

AbstractThe relative roles of rivers versus refugia in shaping the high levels of species diversity in tropical rainforests have been widely debated for decades. Only recently has it become possible to take an integrative approach to test predictions derived from these hypotheses using genomic sequencing and paleo‐species distribution modeling. Herein, we tested the predictions of the classic river, refuge, and river‐refuge hypotheses on diversification in the arboreal sub‐Saharan African snake genus Toxicodryas. We used dated phylogeographic inferences, population clustering analyses, demographic model selection, and paleo‐distribution modeling to conduct a phylogenomic and historical demographic analysis of this genus. Our results revealed significant population genetic structure within both Toxicodryas species, corresponding geographically to river barriers and divergence times from the mid‐Miocene to Pliocene. Our demographic analyses supported the interpretation that rivers are indications of strong barriers to gene flow among populations since their divergence. Additionally, we found no support for a major contraction of suitable habitat during the last glacial maximum, allowing us to reject both the refuge and river‐refuge hypotheses in favor of the river‐barrier hypothesis. Based on conservative interpretations of our species delimitation analyses with the Sanger and ddRAD data sets, two new cryptic species are identified from east‐central Africa. This study highlights the complexity of diversification dynamics in the African tropics and the advantages of integrative approaches to studying speciation in tropical regions.
Niche partitioning of avian predators in northern grasslands amended by biosolids
Authors: Ormrod Arianna E. C. , Doyle Francis I. , Lawson Kirstie J. , Hodges Karen E. 
Published: May 2021

AbstractMany food webs are affected by bottom‐up nutrient addition, as additional biomass or productivity at a given trophic level can support more consumers. In turn, when prey are abundant, predators may converge on the same diets rather than partitioning food resources. Here, we examine the diets and habitat use of predatory and omnivorous birds in response to biosolids amendment of northern grasslands used as grazing range for cattle in British Columbia, Canada. From an ecosystem management perspective, we test whether dietary convergence occurred and whether birds preferentially used the pastures with biosolids. Biosolids treatments increased Orthoptera densities and our work occurred during a vole (Microtus spp.) population peak, so both types of prey were abundant. American Kestrels (Falco sparverius) consumed both small mammals and Orthoptera. Short‐eared Owls (Asio flammeus) and Long‐eared owls (Asio otus) primarily ate voles (>97% of biomass consumed) as did Northern Harriers (Circus hudsonius, 88% vole biomass). Despite high dietary overlap, these species had minimal spatial overlap, and Short‐eared Owls strongly preferred pastures amended with biosolids. Common Ravens (Corvus corax), Black‐billed Magpies (Pica hudsonia), and American Crows (Corvus brachyrhynchos) consumed Orthoptera, Coleoptera, vegetation, and only a few small mammals; crows avoided pastures with biosolids. Thus, when both insect and mammalian prey were abundant, corvids maintained omnivorous diets, whereas owls and Harriers specialized on voles. Spatial patterns were more complex, as birds were likely responding to prey abundance, vegetation structure, and other birds in this consumer guild.
Genetic signature of the natural gene pool ofTilia cordataMill. in Lithuania: Compound evolutionary and anthropogenic effects
Authors: Danusevičius Darius , Kembrytė Rūta , Buchovska Jurata , Baliuckas Virgilijus , Kavaliauskas Darius 
Published: May 2021

AbstractTilia cordataMill. is a valuable tree species enriching the ecological values of the coniferous‐dominated boreal forests in Europe. Following the historical decline, spreading ofTiliasp. is challenged by the elevated inbreeding and habitat fragmentation. We studied the geographical distribution of genetic diversity ofTilia cordatapopulations in Lithuania. We used 14 genomic microsatellite markers to genotype 543 individuals from 23 wild‐growing populations. We found thatTilia cordataretained high levels of genetic diversity (populationFIS = 0–0.15,Ho = 0.53–0.69,He = 0.56–0.75). AMOVA, Bayesian clustering, and Monmonier's barrier detection indicate weak but significant differentiation among the populations (FST = 0.037***) into geographically interpretable clusters of (a) western Lithuania with high genetic heterogeneity but low genetic diversity, bottleneck effects, (b) relatively higher genetic diversity ofTilia cordataon rich and most soils of midland lowland, and (c) the most differentiated populations on poor soils of the coolest northeastern highland possessing the highest rare allele frequency but elevated inbreeding and bottleneck effects. Weak genetic differentiation among theTilia cordatapopulations in Lithuania implies common ancestry, absence of strong adaptive gradients, and effective genetic exchange possible mediated via the riparian networks. A hypothesis on riparian networks as gene flow mediators inTilia cordatawas raised based on results of this study.
The effect of sampling density and study area size on landscape genetics inferences for the Mississippi slimy salamander (Plethodon mississippi)
Authors: Burgess Stephanie M. , Garrick Ryan C. 
Published: May 2021

AbstractIn landscape genetics, it is largely unknown how choices regarding sampling density and study area size impact inferences upon which habitat features impede vs. facilitate gene flow. While it is recommended that sampling locations be spaced no further apart than the average individual's dispersal distance, for low‐mobility species, this could lead to a challenging number of sampling locations, or an unrepresentative study area. We assessed the effects of sampling density and study area size on landscape genetic inferences for a dispersal‐limited amphibian, Plethodon mississippi, via analysis of nested datasets. Microsatellite‐based genetic distances among individuals were divided into three datasets representing sparse sampling across a large study area, dense sampling across a small study area, or sparse sampling across the same small study area. These datasets were a proxy for gene flow (i.e., the response variable) in maximum‐likelihood population effects models that assessed the nature and strength of their relationship with each of five land‐use classes (i.e., potential predictor variables). Comparisons of outcomes were based on the rank order of effect, sign of effect (i.e., gene flow resistance vs. facilitation), spatial scale of effect, and functional relationship with gene flow. The best‐fit model for each dataset had the same sign of effect for hardwood forests, manmade structures, and pine forests, indicating the impacts of these land‐use classes on dispersal and gene flow in P. mississippi are robust to sampling scheme. Contrasting sampling densities led to a different inferred functional relationship between agricultural areas and gene flow. Study area size appeared to influence the scale of effect of manmade structures and the sign of effect of pine forests. Our findings provided evidence for an influence of sampling density, study area size, and sampling effort upon inferences. Accordingly, we recommend iterative subsampling of empirical datasets and continued investigation into the sensitivities of landscape genetic analyses using simulations.
Drivers of diversity and community structure of bees in an agroecological region of Zimbabwe
Authors: Tarakini Gugulethu , Chemura Abel , Tarakini Tawanda , Musundire Robert 
Published: May 2021

Abstract

Worldwide bees provide an important ecosystem service of plant pollination. Climate change and land‐use changes are among drivers threatening bee survival with mounting evidence of species decline and extinction. In developing countries, rural areas constitute a significant proportion of the country's land, but information is lacking on how different habitat types and weather patterns in these areas influence bee populations.

This study investigated how weather variables and habitat‐related factors influence the abundance, diversity, and distribution of bees across seasons in a farming rural area of Zimbabwe. Bees were systematically sampled in five habitat types (natural woodlots, pastures, homesteads, fields, and gardens) recording ground cover, grass height, flower abundance and types, tree abundance and recorded elevation, temperature, light intensity, wind speed, wind direction, and humidity. Zero‐inflated models, censored regression models, and PCAs were used to understand the influence of explanatory variables on bee community composition, abundance, and diversity.

Bee abundance was positively influenced by the number of plant species in flower (p < .0001). Bee abundance increased with increasing temperatures up to 28.5°C, but beyond this, temperature was negatively associated with bee abundance. Increasing wind speeds marginally decreased probability of finding bees.

Bee diversity was highest in fields, homesteads, and natural woodlots compared with other habitats, and the contributions of the genus Apis were disproportionately high across all habitats. The genus Megachile was mostly associated with homesteads, while Nomia was associated with grasslands.

Synthesis and applications. Our study suggests that some bee species could become more proliferous in certain habitats, thus compromising diversity and consequently ecosystem services. These results highlight the importance of setting aside bee‐friendly habitats that can be refuge sites for species susceptible to land‐use changes.
Relaxation of putative plant defenses in a tropical agroecosystem
Authors: Carley Lauren N. , Letcher Susan G. 
Published: May 2021

AbstractEvidence of the effects of agriculture on natural systems is widespread, but potential evolutionary responses in nontarget species are largely uncharacterized. To explore whether exposure to agrochemicals may influence selective pressures and phenotypic expression in nonagricultural plant populations, we characterized the expression of putative antiherbivore defense phenotypes in three nonagricultural species found upstream and downstream of irrigated rice fields in Guanacaste Province, Costa Rica. We found that plants downstream of chemically intensive agriculture showed shifts toward reduced expression of putative antiherbivore defenses relative to upstream counterparts. In two of three tested species, leaf extracts from downstream plants were more palatable to a generalist consumer, suggesting a possible reduction of chemical defenses. In one species with multiple modes of putative defenses, we observed parallel reductions of three metrics of putative biotic and physical defenses. These reductions were concurrent with reduced herbivore damage on downstream plants. Together, these results suggest that agriculture has the potential to alter intraspecific phenotypic expression, ecological interactions, and natural selection in nontarget plant populations.
Screening potential insect vectors in a museum biorepository reveals undiscovered diversity of plant pathogens in natural areas
Authors: Trivellone Valeria , Wei Wei , Filippin Luisa , Dietrich Christopher H. 
Published: May 2021

AbstractPhytoplasmas (Mollicutes,Acholeplasmataceae), vector‐borne obligate bacterial plant parasites, infect nearly 1,000 plant species and unknown numbers of insects, mainly leafhoppers (Hemiptera, Deltocephalinae), which play a key role in transmission and epidemiology. Although the plant–phytoplasma–insect association has been evolving for >300 million years, nearly all known phytoplasmas have been discovered as a result of the damage inflicted by phytoplasma diseases on crops. Few efforts have been made to study phytoplasmas occurring in noneconomically important plants in natural habitats. In this study, a subsample of leafhopper specimens preserved in a large museum biorepository was analyzed to unveil potential new associations. PCR screening for phytoplasmas performed on 227 phloem‐feeding leafhoppers collected worldwide from natural habitats revealed the presence of 6 different previously unknown phytoplasma strains. This indicates that museum collections of herbivorous insects represent a rich and largely untapped resource for discovery of new plant pathogens, that natural areas worldwide harbor a diverse but largely undiscovered diversity of phytoplasmas and potential insect vectors, and that independent epidemiological cycles occur in such habitats, posing a potential threat of disease spillover into agricultural systems. Larger‐scale future investigations will contribute to a better understanding of phytoplasma genetic diversity, insect host range, and insect‐borne phytoplasma transmission and provide an early warning for the emergence of new phytoplasma diseases across global agroecosystems.