Natural Populations Research Articles

Mobility patterns in Austrian and Italian municipalities in the decade before and during the COVID‐19 era

AbstractIn European countries, where the demographic transition has reached advanced stages and the natural increase has fallen below zero, migration constitutes a significant component of local population change. We investigate to what extent the dynamics of international migration and internal mobility changed during the first waves of the COVID‐19 pandemic, compared to the previous decade. We focus on Austrian and Italian municipalities to assess the contribution of migration components to local population growth, using official data provided by National Statistical Institutes on inflows and outflows of migrant and native populations, from 2010 to 2020. The adoption of harmonized degrees of urbanization allows us to profile spatial and demographic patterns of mobility, in the Austrian and Italian territories. We apply Bayesian‐Geostatistical models, and Artificial Neural‐Networks to investigate the potential determinants of mobility variability. The results reveal Austrian and Italian population‐specific migration trends. Overall, the trends observed in the decade before the pandemic were either confirmed or further accentuated during the COVID‐19 era. Although rural‐urban mobility generally persisted in both countries, counter‐urbanization trends were detected among Austrian populations during the initial period of the COVID‐19 pandemic. Conversely, urban and intermediate municipalities in Italy maintained their attractiveness and capacity to retain Italian populations. These findings offer new empirical insights into urbanization dynamics in a comparative perspective, which are particularly relevant for the definition of European regional policy aimed at matching local needs with national social cohesion goals.

Musa species in mainland Southeast Asia: From wild to domesticate.

Many species are defined in the Musa section within its natural diversification area in Southeast Asia. However, their actual number remains debated as botanical characterisation, distribution and intraspecific variability are still poorly known, compromising their preservation and their exploitation as crop wild relatives of cultivated forms. To address the underexplored Musa diversity in mainland Southeast Asia, at the northern edge of the natural range, 208 specimens were collected in Vietnam, Laos and China, mainly belonging to Musa balbisiana, M. itinerans, M. acuminata and M. yunnanensis. Data on location, morphology, environment and local knowledge were recorded, and leaf samples collected for high-throughput genotyping. This study combines geographical, morphological, and genomic diversity to clarify the taxonomic classification. The collected species exhibit highly distinctive morphologies and genomes, just as they differ in ranges and life traits. Intraspecific genomic diversity was also observed, although not necessarily morphologically perceptible. Mainland Southeast Asia is confirmed as a primary diversification centre for the Musa section. The diversity observed is only partially represented in major international ex situ collections, calling for their urgent enrichment and the promotion of in situ management procedures, for the protection of these threatened species and to better harness their potential in breeding programmes. Although considered wild, the species studied are all affected to varying extents by human use. Musa yunnanensis and M. acuminata subsp. burmannica are the most strictly wild forms, with spontaneous interspecific hybrids first described in this study. Although gathered as fodder, they were only occasionally dispersed outside their endemic zones. Musa itinerans is not cultivated per se, but natural populations are widely exploited, leading to a geographically structured diversity. The diversity of M. balbisiana is widely distributed and geographically structured by human activities. This species should be regarded as domesticated. These various stages, from simple opportunistic gathering to true domestication, shed light on the evolutionary history of today's cultivated varieties.

The Quality of Embedding Charges Is Critical for Convergence of Many-Body Expansions When BSSE Is Absent.

There is conflicting evidence in the literature concerning the benefits of charge embedding on the convergence of many-body expansions (MBEs). Using a systematic series of water and ion-water clusters of varying size, this study indicates that the effects of charge embedding can be masked by basis set superposition error (BSSE). When BSSE is removed, this study demonstrates that charge embedding can significantly accelerate MBE convergence, where the electrostatically embedded two-body method, EE-MBE(2), can often yield accuracy close to the four-body method, MBE(4). Contrary to previous studies on smaller systems, this work shows that the performance of EE-MBE is highly sensitive to the charge model, with the best performance obtained when the natural population analysis (NPA) charge model is used and generated at the same level of theory used in the subsystem and supersystem calculations. It was demonstrated that the "3c" composite method, PBEh-3c, yields NPA atomic charges that are in excellent agreement with those obtained from supersystem density functional theory calculations. The linear-scaling X-Polarization method provides a more general approach to estimating these supersystem QM atomic charges, but its performance depends on how the fragments are defined.

Assessing the Impacts of Adaptation to Native-Range Habitats and Contemporary Founder Effects on Genetic Diversity in an Invasive Fish.

Species invading non-native habitats can cause irreversible environmental damage and economic harm. Yet, how introduced species become widespread invaders remains poorly understood. Adaptation within native-range habitats and rapid adaptation to new environments may both influence invasion success. Here, we examine these hypotheses using 7058 SNPs from 36 native, 40 introduced and 19 farmed populations of tench, a fish native to Eurasia. We examined genetic structure among these populations and accounted for long-term evolutionary history within the native range to assess whether introduced populations exhibited lower genetic diversity than native populations. Subsequent to infer genotype-environment correlations within native-range habitats, we assessed whether adaptation to native environments may have shaped the success of some introduced populations. At the broad scale, two glacial refugia contributed to the ancestry and genomic diversity of tench. However, native, introduced and farmed populations of admixed origin exhibited up to 10-fold more genetic diversity (i.e., observed heterozygosity, expected heterozygosity and allelic richness) compared to populations with predominantly single-source ancestry. The effects of introduction to a new location were also apparent as introduced populations exhibited fewer private alleles (mean = 9.9 and 18.9 private alleles in introduced and native populations, respectively) and higher population-specific Fst compared to native populations, highlighting their distinctiveness relative to the pool of allelic frequencies across tench populations. Finally, introduced populations with varying levels of genetic variation and similar genetic compositions have become established and persisted under strikingly different climatic and ecological conditions. Our results suggest that lack of prior adaptation and low genetic variation may not consistently hinder the success of introduced populations for species with a demonstrated ability to expand their native range.

Land snail Δ47 thermometry using cultured and European natural populations of Clausilia pumila, Succinella oblonga and Trochulus hispidus

Clumped isotope composition (Δ47) of aragonitic shells of terrestrial molluscs allow the quantitative reconstructions of continental paleotemperatures from loess-paleosol records of the last 2.5 million years, but it needs testing the method under controlled laboratory conditions and using natural populations. In this study the stable carbon, oxygen and clumped isotope compositions of cultured individuals and field-collected specimens of three species (Clausilia pumila, Succinella oblonga and Trochulus hispidus), widespread in Quaternary loess deposits in Europe, were measured in the Debrecen (ATOMKI) and ETH Zürich laboratories. Our data of cultured snails demonstrate that shells of the three species record Δ47 signatures close to equilibrium conditions with mostly positive (C. pumila), both positive/negative (T. hispidus), and mostly negative (S. oblonga) offsets on the order of 0.0158 ± 0.0105 ‰ (mean offset±1 SD) compared to the Anderson et al. (2021) unified calibration. Calcification temperatures (TΔ47) derived from C. pumila shells were found to be in excellent agreement with chamber temperatures of 12, 18 and 24 °C, especially in the ATOMKI laboratory (mean T offset: 2.1 ± 2.2 °C, 1 SD), while the other two species exhibited larger discrepancies on the order of 5–8 °C (mean offset). Single shell-based mean TΔ47 values of field-collected molluscs indicated growth temperatures spanning values from the frost-free period to summer season, or even above summer maxima. The sites of natural populations, characterized by different climate conditions, could be grouped using the aridity index (AI) with values of 0.96–1.06 representing mean temperature of the frost-free period (TFFP), and AI ranging either from 0.85 to 0.91 or 1.14 to 1.51 reflecting mean summer season or July temperatures (TJJA/TJ). Multi-shell TΔ47, obtained by homogenizing the material of 3–5 shells of C. pumila and T. hispidus, reflect TJJA in most cases. We observed a dependence of the shell oxygen isotope compositions of the three species on oceanity/continentality with more negative/positive values characteristic for more continental/oceanic sites, likely due to moisture source distance and depletion of rainfall in 18O towards the continental interior. In addition, deviation of body fluid δ18O values (derived from δ18Oshell and Δ47shell) from seasonal precipitation δ18O is also controlled by an additional temperature effect, being independent of the climate zone of the collection site, but co-varying with the site-specific difference between single shell TΔ47 and TJJA.

Long‐Term Maintenance of Complex Chromosomal Inversion Polymorphism in Drosophila mediopunctata

ABSTRACTNatural selection is known to favor specific gene combinations, thereby shaping the evolution of recombination rates, often through epistatic interactions. However, the dynamics of these interacting factors within natural populations remain poorly understood. In this study, we investigate the long‐term maintenance of a complex polymorphism involving linked, nonoverlapping chromosomal inversions in a natural population of Drosophila mediopunctata. Remarkably, even after 30 years—equivalent to roughly 340 generations—two major features have remained unexpectedly stable: the linkage disequilibrium (LD) between inversions, which deviates significantly from the theoretical prediction of decay, and a consistent seasonal cycle pattern of heterozygous excess and homozygous deficiencies. We explored the roles of recombination suppression, epistatic selection, and overdominance in maintaining this stability, examining their alignment with previously described patterns. Our findings reveal that moderate selection coefficients, such as s = 0.0407, are sufficient to maintain the observed LD for the most common haplotypes, albeit leading to an unstable equilibrium. Simulations further reveal that the introduction of overdominance stabilizes the system, enabling the long‐term persistence of this complex inversion polymorphism across various frequency scenarios. The stability of this system appears to hinge on a delicate balance between LD, recombination rates, and selective pressures, with overdominance playing a critical role. Our findings highlight the significance of epistatic interactions and selective pressures in shaping evolutionary pathways in natural populations and offer a compelling example of natural selection acting on a complex inversion polymorphism, providing valuable insights into the evolutionary dynamics governing inversion systems.

Wolbachia infection in natural mosquito populations from Argentina.

The increasing spread of mosquito vectors has made mosquito-borne arboviral diseases a global threat to public health, leading to the urgent need for effective population control methods. Strategies based in the intracellular bacterium Wolbachia Hertig, 1936 are considered environmentally friendly, safe for humans, and potentially cost-effective for controlling arboviral diseases. To minimize undesirable side effects, it is relevant to assess whether Wolbachia is present in the area and understand the diversity associated with native infections before implementing these strategies. With this purpose, we investigated Wolbachia infection status, diversity, and prevalence in populations of Aedes albifasciatus (Macquart, 1838), Aedes fluviatilis (Lutz, 1904), and hybrids of the Culex pipiens (Linnaeus, 1758) complex from Argentina. Aedes albifasciatus and C. pipiens complex samples were collected in the province of Buenos Aires, and A. fluviatilis in the province of Misiones. Aedes albifasciatus was found to be uninfected, while infections with strains wFlu and wPip were detected in A. fluviatilis and hybrids of the C. pipiens complex, respectively. All strains were fixed or close to fixation and clustered within supergroup B. These finding provides valuable information on Wolbachia strains found in natural mosquito populations in Argentina that might be used in heterologous infections in the future or be considered when designing control strategies based on Wolbachia infection.

Antecedent Effect Models as an Exploratory Tool to Link Climate Drivers to Herbaceous Perennial Population Dynamics Data

ABSTRACTUnderstanding mechanisms and predicting natural population responses to climate is a key goal of Ecology. However, studies explicitly linking climate to population dynamics remain limited. Antecedent effect models are a set of statistical tools that capitalize on the evidence provided by climate and population data to select time windows correlated with a response (e.g., survival, reproduction). Thus, these models can serve as both a predictive and exploratory tool. We compare the predictive performance of antecedent effect models against simpler models and showcase their exploratory analysis potential by selecting a case study with high predictive power. We fit three antecedent effect models: (1) weighted mean models (WMM), which weigh the importance of monthly anomalies based on a Gaussian curve, (2) stochastic antecedent models (SAM), which weigh the importance of monthly anomalies using a Dirichlet process, and (3) regularized regressions using the Finnish horseshoe model (FHM), which estimate a separate effect size for each monthly anomaly. We compare these approaches to a linear model using a yearly climatic predictor and a null model with no predictors. We use demographic data from 77 natural populations of 34 plant species ranging between seven and 36 years in length. We then fit models to the asymptotic population growth rate (λ) and its underlying vital rates: survival, development, and reproduction. We find that models including climate do not consistently outperform null models. We hypothesize that the effect of yearly climate is too complex, weak, and confounded by other factors to be easily predicted using monthly precipitation and temperature data. On the other hand, in our case study, antecedent effect models show biologically sensible correlations between two precipitation anomalies and multiple vital rates. We conclude that, in temporal datasets with limited sample sizes, antecedent effect models are better suited as exploratory tools for hypothesis generation.

At the core of salinity: Divergent transcriptomic responses to neutral and alkaline salinity in Arabidopsis thaliana

In the context of current climate change, alkaline salinity is increasingly challenging crop yields, especially in arid and semiarid regions. Alkaline salinity is more detrimental to plant performance than neutral salinity and tolerance to neutral salinity may not confer tolerance to alkaline salinity. The mechanisms behind are still poorly understood. This study aims to identify physiological and genetic traits underlying this differential tolerance to neutral and alkaline salinity by exploiting the variation present in natural populations (demes) of Arabidopsis thaliana. Growth, photosynthesis, phytohormone and mineral nutrient profiles, plant water status and transcriptomic changes were analyzed in four demes with contrasting tolerance to neutral and alkaline salinity. Results of this novel holistic approach suggest low internal Fe use efficiency caused by bicarbonate as a driver of enhanced sensitivity to alkaline salinity in plants adapted to neutral salinity prompting photosynthesis inhibition and alteration of the plant’s carbon budget for primary and secondary metabolism. Moreover, alkaline salinity specifically altered the auxin and jasmonic acid signaling pathways, while sustained ABA biosynthesis was an adaptive trait under neutral salinity. Exploring the genes with non-shared expression trends between salinity types, we identified sequence variation at the BGAL4 locus associated with advantageous responses to each type of salinity. Weighted correlation network analysis (WGCNA) validated the significant involvement of gene co-expression modules targeted by the enrichment analyses, highlighting the hubs correlated with favorable responses to both salinity types. Overall, the present study points out the complex physiological and genetic mechanisms responsible for plant tolerance to alkaline salinity and proposes target genes for breeding strategies under alkaline saline soils.

Intraspecific body size variation across distributional moments reveals trait filtering processes.

Natural populations are composed of individuals that vary in their morphological traits, timing and interactions. The distribution of a trait can be described by several dimensions, or mathematical moments-mean, variance, skew and kurtosis. Shifts in the distribution of a trait across these moments in response to environmental variation can help to reveal which trait values are gained or lost, and consequently how trait filtering processes are altering populations. To examine the role and drivers of intraspecific variation within a trait filtering framework, we investigate variation in body size among five wild bumblebee species in the Colorado Rocky Mountains. First, we examine the relationships between environmental factors (climate and floral food resources) and body size distributions across bumblebee social castes to identify demographic responses to environmental variation. Next, we examine changes in the moments of trait distributions to reveal potential mechanisms behind intraspecific shifts in body size. Finally, we examine how intraspecific body size variation is related to diet breadth and phenology. We found that climate conditions have a strong effect on observed body size variation across all distributional moments, but the filtering mechanism varies by social caste. For example, with earlier spring snowmelt queens declined in mean size and became negatively skewed and more kurtotic. This suggests a skewed filter admitting a greater frequency of small individuals. With greater availability of floral food resources, queens increased in mean size, but workers and males decreased in size. Observed shifts in body size variation also correspond with variation in diet breadth and phenology. Populations with larger average body size were associated with more generalized foraging in workers of short-tongued species and increased specialization in longer-tongued workers. Altered phenological timing was associated with species- and caste-specific shifts in skew. Across an assemblage of wild bumblebees, we find complex patterns of trait variation that may not have been captured if we had simply considered mean and variance. The four-moment approach we employ here provides holistic insight into intraspecific trait variation, which may otherwise be overlooked and reveals potential underlying filtering processes driving such variation within populations.

Functional and evolutionary analysis of key enzymes triacylglycerol lipase, glycogen hydrolases in the glycerol and glucose biosynthesis pathway and cellular chaperones for freeze-tolerance of the Rice stem borer, Chilo suppressalis

Freeze-tolerance is an important physiological trait for terrestrial environmental adaptation and intraspecific geographic-lineage diversification in ectothermic animals, yet there remains a lack of systematic studies on its underlying genetic mechanisms and evolution. To address this problem, we employed the widely distributed rice pest, the Chilo suppressalis, as a model to explore the genetic mechanisms and evolutionary history of freeze-tolerance. First, we systematically characterized its antifreeze mechanisms by performing functional validation of potential key genes in laboratory-reared lines. This revealed the functional roles of glycerol biosynthesis in freeze-tolerance, including the triacylglycerol-originated pathway via triacylglycerol lipase (Tgl) hydrolysis and the glycogen-originated pathway via α-amylase (Aa) and maltase (Ma) hydrolysis, as well as the roles of the cellular chaperones Hsc70 and Hsf1. Then, we investigated the evolution of freeze-tolerance by collecting representative geographical samples and performing population genetic analyses, which suggested differentiated strategies of cold adaptation in different geographic populations. Taken together, our findings demonstrate the functional basis of cold resistance in Chilo suppressalis and reveal the evolutionary history of freeze-tolerance in natural populations, providing insights into organismal freeze-tolerance and clues for pest control.

Scorpion mud turtle breeding in the Amazon: zootechnical and environmental activity for the species conservation

Commercial captive turtle breeding is an opportunity for Kinosternon scorpioides scorpioides conservation, as predatory hunting, destruction and habitat degradation are the main threats to its natural populations. In this sense, the goal of this study is to provide a synthesis of knowledge about the species Embrapa-developed captive breeding system. Below, we have set up the themes in a way that makes sense in the captivity flow, discussing important information about the species in the environmental context and its management from the initial breeding stock formation up to reproductive aspects, highlighting animal behaviour and the environmental approach of the activity, to support commercial breeding from the species conservation perspective. The discussion and conclusions have shown that the species has a low invasive potential in Brazilian biomes; the captivity site needs not much space, facilities or water; captive breeding is a zootechnical and environmentally appropriate activity for the species’ conservation because it is a way to avoid spending on programs that are made only for this purpose; and increasing knowledge of reproduction using molecular genetic tools is important. Keywords: conservation, chelonian, Kinosternon scorpioides, jurará, turtle breeding

A Systematic Review Exploring Empirical Pharmacogenomics Research Within Global Indigenous Populations.

This systematic review aims to highlight the scope of pharmacogenomics research within global Indigenous populations. This review also explores the barriers and facilitators of pharmacogenomics research within this population. A systematic review of literature was conducted to identify and present an understanding of current empirical evidence demonstrating the conduct of genomics or pharmacogenomics research within global Indigenous populations (PROSPERO registration: CRD42021257226). Using key search terms, relevant databases were searched for articles published between January 2010 and July 2022. Screening, data extraction, and analysis was conducted using well-defined inclusion criteria. Quality assessment and risk of bias appraisal was conducted using the mixed methods appraisal tool. Indigenous community engagement and participation in genomics research was assessed using the social-ecological framework. From the 427 articles identified, 77 articles met inclusion criteria and underwent full-text screening. Of these, 30 articles were included in the final review, with 16 being quantitative and 14 either qualitative or mixed methods studies. Most studies were conducted with native Indigenous populations from the United States of America (36%). Content analysis revealed that studies either explored genetic variations associated with disease in Indigenous populations (23%) or markers for drug metabolism (30%) or were designed to understand perspectives of genomics research within this population (47%). Perspectives included the exploration of the role of participants in research, benefits or outcomes achieved from participation in genomics research, and levels of Indigenous engagement and participation in genomics research. This review highlights a growing gap in Indigenous genomics research globally. It presents several important considerations from Indigenous participants, identifying how researchers can co-create culturally safe and inclusive design, implementation, analysis, and subsequent outcomes of genomics research involving Indigenous people. Indigenous governance, self-determination and leadership is essential, with researchers required to be responsive to such fundamental partnerships for research to progress.

The Cancer Equity Compass: Interactive maps showing the association between social determinants of health and cancer disparities.

149 Background: Cancer incidence and mortality in Black, Hispanic and Native American populations is over twice that in the White population for some prevalent cancers. A new, publicly available mapping tool, the Cancer Equity Compass (CEC), was developed to inform data-driven initiatives to improve equity by identifying community factors associated with cancer disparities. The tool is comprised of interactive maps that visually reveal correlations between two variables. Development of the tool began with assembling a group of nine advisors with expertise in cancer prevention, treatment and health equity. These experts inform the strategy, data sources, variables of interest, and stakeholder value propositions for the CEC. Methods: The data source for the CEC is a national, multi-level database developed using individual, health system, and community data, aggregated by county. For the three most common cancers in the U.S., breast, prostate and lung, screening and prevalence rates were collected from 2021 Medicare 5% research identifiable files and mortality rates from 2020 SEER Medicare rates. These metrics were each mapped with a variety of social determinants of health (SDOH) variables. Population rates for minorities, education, poverty, income and unemployment, and an air quality measure were from the Area Health Resources File. Environmental risks were derived from the Environmental Justice Index and included environmental burden (ranked 0-17 for pollution, toxic sites, built environment, transportation infrastructure and water pollution), air pollution (ranked 0-4), and social vulnerability (ranked 0-14 across socioeconomic variables). Results: Each map includes one cancer metric and one SDOH variable. Each variable is stratified to show the top quartile, middle 50%, and bottom quartile. The choropleth heat maps, created on Tableau, display 9 colors representing each combination of the three levels (>75%, 25-75%, <25%) for both mapped variables. The CEC currently has 140 maps presenting visualizations of county SDOH associations with cancer disparities. Conclusions: The expert advisors on the project have outlined four avenues for the CEC to aid efforts to improve cancer equity: 1) Enhance diversity in clinical trial recruitment and data registries through targeted site recruitment; 2) Identify high opportunity targets for improving equity and informing solutions; 3) Identify common correlates of disparities within and across U.S. counties to direct priorities for national policy and programs for large-scale impact; and 4) Measure change to support improvement efforts and report impact of equity initiatives. The CEC will be expanded with additional measures including healthcare access. The goal is use by stakeholders and changemakers who can apply the reported data to fuel advocacy efforts and enact positive change.

Gene Drive and Symbiont Technologies for Control of Mosquito-Borne Diseases.

Mosquito-borne diseases, such as dengue and malaria, pose a significant burden to global health. Current control strategies with insecticides are only moderately effective. Scalable solutions are needed to reduce the transmission risk of these diseases. Symbionts and genome engineering-based mosquito control strategies have been proposed to address these problems. Bacterial, fungal, and viral symbionts affect mosquito reproduction, reduce mosquito lifespan, and block pathogen transmission. Field tests of endosymbiont Wolbachia-based methods have yielded promising results, but there are hurdles to overcome due to the large-scale rearing and accurate sex sorting required for Wolbachia-based suppression approaches and the ecological impediments to Wolbachia invasion in replacement approaches. Genome engineering-based methods, in which mosquitoes are genetically altered for the modification or suppression of wild populations, offer an additional approach for control of mosquito-borne diseases. In particular, the use of gene drive alleles that bias inheritance in their favor is a potentially powerful approach. Several drives are frequency dependent, potentially giving them broadly similar population dynamics to Wolbachia. However, public acceptance and the behavior of released drives in natural mosquito populations remain challenges. We summarize the latest developments and discuss the knowledge gaps in both symbiont- and gene drive-based methods.

Evaluating the Presence of Interspecific Hybrids Among Piaractus mesopotamicus, Piaractus brachypomus and Colossoma macropomum in the Upper Paraná River Using Genetic Markers

ABSTRACTFish hybridization is common in aquaculture worldwide, including in Brazil, with cross‐breeding between species of the genera Piaractus and Colossoma taking the lead. However, little is known about the genetic damage caused by hybrids that escape into natural environments. In the upper Paraná River region, hybrid fishes are overproduced; therefore, the use of molecular techniques for their monitoring and identification is necessary. This study aimed to detect the presence of possible hybridization between Piaractus and Colossoma in the upper Paraná River using the molecular markers cytochrome c oxidase subunit 1 (COI) and α‐tropomyosin (TROP). Fragments from 53 fish samples were analysed, and 41 samples were considered hybrids, with 12 confirmed pure, six as Piaractus mesopotamicus (pacu) and six as Piaractus brachypomus (pirapitinga). This is the first record of P. brachypomus, which is an invasive species in this basin, while Colossoma macropomum has not been observed. Molecular markers efficiently detected hybrids in the Ivinhema and Paraná rivers. The results showed a predominance of hybrid specimens from P. mesopotamicus × P. brachypomus. Our study suggests that more restrictions on hybridization and better supervision of fish farms are needed to prevent the escape of hybrids and the consequent ecological and genetic damage to native populations. We warn of the risk of a decline in the population of P. mesopotamicus, as this species is of great importance for fishing and maintaining the ecosystem.

Relationship Between Genetic and Phenotypic Variations in Natural Populations of Perennial and Biennial Sagebrush.

Plant responses to environmental heterogeneity depend on life-history traits, which could relate to phenotypical and genetic characteristics. To elucidate this relationship, we examined the variation in population genetics and functional traits of short- and long-lived Artemisia species that are co-occurring in the steppes of Mongolia. Mongolian steppes represent stressful and water-limited habitats, demanding phenotypic modifications in the short term and/or genetic adaptation in the long term. However, detailed knowledge is missing about both plant phenotypic and genetic differentiation, and their interrelationships in temperate grasslands. Here, we investigated 21 populations of the widely distributed subshrub Artemisia frigida and the herbaceous biennial Artemisia scoparia. Genetic variation was assessed with newly developed simple sequence repeats (SSRs) markers. Functional trait data were collected from each individual, and data on environmental variables was collected for each population. We detected significantly higher genetic diversity in the biennial species (H E = 0.86) compared with the perennial (H E = 0.79). For both species, the largest share of genetic variation was partitioned within populations (96%). Population genetic structure in the biennial A. scoparia was weak, while the perennial A. frigida showed some spatial genetic structure, which was impacted by geographical factors, soil nutrients, and precipitation amount. Morphology-related functional traits (i.e., plant height) were predominantly associated with environmental variables rather than with genetic variation, whereas physiology-related trait (i.e., specific leaf area [SLA]) was partly genetically determined.

Increased offspring size and reduced gestation length in an ectothermic vertebrate under a worst-case climate change scenario

As global temperatures continue to rise, understanding the impacts of warming environments has become increasingly important. Temperature is especially relevant for ectothermic organisms which depend upon consistent and predictable annual temperature cycles for reproduction and development. However, additional research is required in this area to elucidate the potential impacts of climate change on future generations. To understand how projected increases in environmental temperatures may impact reproductive outcomes within natural populations of ectothermic vertebrates, we manipulated minimum ambient temperatures during gestation in Red-sided garter snakes (Thamnophis sirtalis parietalis). Wild snakes were collected in the Interlake region of Manitoba, Canada during their spring mating season and allowed to mate in controlled conditions. For the duration of gestation, mated females were placed into one of two ambient thermal conditions: temperatures emulating those found in the species’ natural habitat or temperatures with a consistent 5 °C increase to match end-of-century climate change projections. We recorded observations for each litter and all neonates resulting from controlled mating trials. We observed no difference in litter sizes or birth rates between thermal conditions. However, we observed a significant reduction in gestation length and significant increase to neonate body mass and body condition associated with increased ambient temperatures. These results suggest that increased minimum temperatures during gestation may confer reproductive benefits for the northern populations of this species even under the most extreme current modeled warming predictions. We discuss the broader implications of this effect, including possible negative ecological outcomes.

Seasonal Patterns of Resource Use Within Natural Populations of Burying Beetles.

For organisms in temperate environments, seasonal variation in resource availability and weather conditions exert fluctuating selection pressures on survival and fitness, resulting in diverse adaptive responses. By manipulating resource availability on a local spatial scale, we studied seasonal patterns of resource use within natural populations of burying beetles Nicrophorus vespilloides in a Norfolk woodland. Burying beetles are necrophagous insects that breed on vertebrate carcasses. They are active in Europe between April and October, after which they burrow into the soil and overwinter. Using breeding and chemical analyses, we compared the fecundity and physiological state of beetles that differed in their seasonal resource use. We found seasonal variation in carrion use by wild burying beetles and correlated differences in their reproductive success and cuticular hydrocarbon profiles. Our results provide novel insight into the seasonal correlates of behaviour, physiology and life history in burying beetles.

The contribution of nearshore oceanography to temporal variation in larval dispersal.

Patterns of population connectivity shape ecological and evolutionary phenomena from population persistence to local adaptation and can inform conservation strategy. Connectivity patterns emerge from the interaction of individual behavior with a complex and heterogeneous environment. Despite ample observation that dispersal patterns vary through time, the extent to which variation in the physical environment can explain emergent connectivity variation is not clear. Empirical studies of its contribution promise to illuminate a potential source of variability that shapes the dynamics of natural populations. We leveraged simultaneous direct dispersal observations and oceanographic transport simulations of the clownfish Amphiprion clarkii in the Camotes Sea, Philippines, to assess the contribution of oceanographic variability to emergent variation in connectivity. We found that time-varying oceanographic simulations on both annual and monsoonal timescales partly explained the observed dispersal patterns, suggesting that temporal variation in oceanographic transport shapes connectivity variation on these timescales. However, interannual variation in observed mean dispersal distance was nearly 10 times the expected variation from biophysical simulations, revealing that additional biotic and abiotic factors contribute to interannual connectivity variation. Simulated dispersal kernels also predicted a smaller scale of dispersal than the observations, supporting the hypothesis that undocumented abiotic factors and behaviors such as swimming and navigation enhance the probability of successful dispersal away from, as opposed to retention near, natal sites. Our findings highlight the potential for coincident observations and biophysical simulations to test dispersal hypotheses and the influence of temporal variability on metapopulation persistence, local adaptation, and other population processes.