Find research datasets worth reusing

Data from: The contribution of carbon budget to masting intervals in Veratrum album populations inhabiting different elevations

Premise: Mast flowering/seeding is often more extreme in lower-resource environments, such as alpine compared to lowland habitats. We studied a masting herb which had less extreme masting at higher elevations, and tested if this difference could be explained by higher photosynthetic productivity and/or lower reproductive investment at the higher elevation sites. Methods: We examined the relationship between flowering intervals and carbon budget (i.e., the balance between reproductive investment and annual carbon fixation) in a masting herb, Veratrum album subsp. oxysepalum, across five lowland and six alpine populations in northern Japan. We evaluated the previous flowering histories of individual plants based on rhizome morphology and analyzed the masting patterns of individual populations. Total mass of the reproductive organs, as a proxy of reproductive investment, was compared between the lowland and alpine populations. Annual carbon fixation was estimated based on photosynthetic capacity, total leaf area per plant, and seasonal transition of light availability. Results: Interval between high-flowering years was shorter and total reproductive investment was smaller in the alpine than in the lowland populations. Owing to its high photosynthetic capacity and continuous bright conditions, annual carbon fixation per plant was 1.5 times greater at the alpine habitat than at the lowland habitat. These results suggest that V. album alpine populations have shorter flowering intervals than lowland populations due to faster recovery from energy loss after reproduction. Conclusions: Our study demonstrated that masting intervals in V. album populations can be explained by habitat-specific carbon budget balances.

Microsatellite exploration in the climbing hydrangea (Hydrangea petiolaris Siebold & Zucc.) transcriptome: A resource for population genetics and functional genomics

Background Hydrangea petiolaris Siebold & Zucc., also known as climbing hydrangea, is a vine native to the woodlands of Korea, Japan, and Sakhalin Island. It is an economically important ornamental plant with fertile and sterile flowers. Despite the recent increase in Hydrangea breeding and interest in germplasm conservation, relatively little is known about the relationships between Hydrangea species. Results We employed Illumina NovaSeq 6000 sequencing technology to generate a total of 39,945,480 reads, which were assembled into 137,715 contigs. A total of 109,092 filtered transcripts were used to identify microsatellites, and 54,587 microsatellite repeat motifs were revealed within 33,556 contigs. Among these, 4,510 transcripts harboring microsatellites had Gene Ontology annotations, and numerous microsatellite-containing transcripts exhibited associations with genes, including those encoding PPR proteins, aldehyde dehydrogenases, and bHLH transcription factors, related to the restorer of fertility (Rf) genes, which play a critical role in restoring fertility in plants with cytoplasmic male sterility. Validation of transcriptomic SSR markers demonstrated high levels of polymorphism, revealing significant genetic diversity within populations. However, null alleles and deviations from Hardy‒Weinberg equilibrium at specific loci suggested caution in genotyping accuracy. Population-level analysis disclosed high genetic differentiation and distinct clustering of populations. Conclusions The H. petiolaris transcriptomic SSR markers offer valuable insight for gaining insights into the population genetics, evolutionary background, and practical strategies for conserving this species. Moreover, the microsatellite loci we have identified and their associations with annotated genes hold promise for creating functional markers specifically tailored for H. petiolaris. These markers include valuable resources of transcriptomic SSR markers suitable for population genetic investigations and have a reasonable degree of applicability across different taxa.

Data from: Rapid evolution of flower phenology and clonality in restored populations of multiple grassland species

<ol> <li>Restoration of terrestrial ecosystems often requires re-introduction of plants. In restored sites, the plants often face environments that differ from those of natural populations. This can affect plant traits, reduce performance and impose novel selection pressures. As a response, restored populations might rapidly evolve and adapt to the novel conditions. This may enhance population survival and contribute to restoration success but has been rarely tested so far.</li> <li>Here, we focused on populations of three grassland species restored 20 years ago (Galium wirtgenii, Inula salicina and Centaurea jacea) by the transfer of green hay, and compared them with donor populations that were the source of the hay. We measured plants both in situ and in a common garden under control and three stress conditions.</li> <li>In-situ, plants in restored sites flowered earlier than plants in donor sites in two out of the three species. In the common garden, plants from the restored populations flowered earlier (in Galium) or showed increased plasticity of clonal propagation in response to clipping (in Inula). Both these traits suggest rapid adaptation to the contrasting mowing regimes in restored in comparison to the donor sites. In Centaurea, we detected no differentiation, neither in situ nor in the common garden.</li> <li> Synthesis and applications: Grassland plants introduced into degraded habitats within the framework of ecological restoration may quite commonly evolve in response to novel selection pressures at restored sites. This rapid evolution likely increases the plant's adaptation to the new conditions of the restored grassland and thus enhances the likelihood of survival of the population and ultimately restoration success. While most practitioners do not consider evolution to be part of restoration, our finding highlights that restored populations of grassland species can be systems with considerable eco-evolutionary dynamics.</li> </ol>

Anthropogenic disturbance driving population decline of a dominant tree in East Asia evergreen broadleaved forests over the last 11,000 years

Current biodiversity loss was generally considered to be caused by anthropogenic disturbance, but when anthropogenic activities began to impact biodiversity loss is still controversial. One hypothesis suggested it was from the industrial era, while others proposed that the anthropogenic disturbance had already resulted in biodiversity decline since the Early Holocene. To test these hypotheses, we focus on subtropical East Asia, which has witnessed a land use and anthropogenic history since the Early Holocene. We selected the unique vegetation of evergreen broadleaved forests (EBLFs), using a genomic approach to infer the demographic history of a dominant plant (Litsea elongata) of EBLFs, and to further detangle the impact of climate change and/or anthropogenic disturbance on effective population size fluctuation. Nine well-defined geographical clades were identified within extant populations of L. elongata. The estimated historical population sizes of these clades all contracted, indicating persistent population decline over the last 11,000 years. Significant correlation was detected between demographic history and three anthropogenic disturbance factors, rather than the climate change in the Holocene. Therefore, we provided the dataset used for phylogenomic analysis, demographic history inference, and correlation analysis in this study.

Bromeliad populations perform distinct ecological strategies across a tropical elevation gradient

<ol> <li>The effect of environmental gradients on the remarkable diversity of mountain-associated plants and on the species' abilities to cope with climate change transcends species-specific strategies. For instance, our understanding of the impact of thermal gradients on ecological divergences in populations of widely distributed species is limited, although it could provide important insights regarding species' response to climate change.</li> <li>Here, we investigated whether populations of an endemic species broadly distributed across an elevation gradient employ unique or multiple divergent ecological strategies according to specific environmental conditions. We hypothesized that populations employ distinct strategies, producing a tolerance-avoidance trade-off related to the thermal conditions they experience across elevations.</li> <li>We conducted our research with 125 individuals of Pitcairnia flammea (Bromeliaceae) sampled from various elevations spanning from sea level to ~2,200 meters and cultivated under the same conditions. To assess specific ecological strategies of P. flammea populations across elevations, we examined leaf temperature, heat and cold tolerances, as well as other structural/morphological, optical, physiological, and biochemical leaf traits.</li> <li>We majorly observed that water-saving traits diminish as elevation increases while membrane fluidity, majorly associated with unsaturated and very-long-chain lipids, enhances. Low-elevation individuals of P. flammea invest in water storage tissues, which likely prevent excessive water loss through the intense transpiration rates under warming periods. Conversely, high-elevation plants exhibit increased membrane fluidity, a possible response to the stiffening induced by low temperature.</li> <li>Our results revealed a tolerance-avoidance trade-off related to thermal strategies of populations distributed across an elevation gradient. Low-elevation plants avoid excessive leaf temperature by investing in water-saving traits to maintain transpiration rates. High-elevation individuals, in turn, tend to invest in membrane properties to tolerate thermal variations, particularly cold events.</li> <li>Our findings challenge the conventional notion that plants' vulnerability to warming depends on species-specific thermal tolerance by showing diverse thermal strategies on populations across an elevation gradient.</li> </ol>

Data from: Abundance models of endemic birds of the Sierra Nevada de Santa Marta, northern South America, suggest small population sizes and dependence on montane elevations

Abundance measures are almost non-existent for several bird species threatened with extinction, particularly range-restricted Neotropical taxa, for which estimating population sizes can be challenging. Here we use data collected over nine years to explore the abundance of 11 endemic birds from the Sierra Nevada de Santa Marta (SNSM), one of Earth's most irreplaceable ecosystems. We established 99 transects in the "Cuchilla de San Lorenzo" Important Bird Area within native forest, early successional vegetation, and areas of transformed vegetation by human activities. A total of 763 bird counts were carried out covering the entire elevation range in the study area (~175–2650 m). We applied hierarchical distance-sampling models to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size. Most species were more abundant in the montane elevational range (1800–2650 m). Habitat-related differences in abundance were only detected for five species, which were more numerous in either early succession, secondary forest, or transformed areas. Inferences of effective population size indicated that at least four endemics likely maintain populations no larger than 15,000–20,000 mature individuals. Estimates of species' area of occupancy and effective population size were lower than most values previously described, a possible consequence of increasing anthropogenic threats. At least four of the endemics exceeded criteria for threatened species listing and a thorough evaluation of their extinction risk should be conducted. Population strongholds for most of the study species were located on the northern and western slopes of the SNSM between 1500–2700 m. We highlight the urgent need for facilitating effective protection of native vegetation in premontane and montane ecosystems to safeguard critical habitats for the SNSM's endemic avifauna. Follow-up studies collecting abundance data across the SNSM are needed to obtain precise range-wide density estimations for all species.

Increased ladybird predation and metabolism do not counterbalance increased field aphid population growth under experimental warming

<ol> <li>Climate change may have diverse and complex impacts on species interactions, destabilizing food webs and ecosystem services. The effects of warming on the top-down biological control of crop pests have been considerably less studied than bottom-up effects through crop physiological changes.</li> <li>We studied the effect of a 2 °C warming in the laboratory and in wheat fields on the predation and metabolism of Harmonia axyridis on wheat aphids using molecular gut content analysis. We also measured the effects of warming on the predation rate and functional response of H. axyridis on each aphid species in the laboratory, as well as on DNA degradation rate.</li> <li>Field densities of Sitobion avenae and Rhopalosiphum padi, the two most abundant wheat aphid species, were increased by 2 and 2.5 times, respectively, under experimental warming, but densities of H. axyridis were not. Field predation rate of H. axyridis on these two aphids was found to be about 25% lower under elevated temperature. This could have been due to faster prey digestion, since degradation of the preferred aphid species, Sitobion avenae, was 1.5 times faster under elevated temperature. However, the functional response of H. axyridis larvae on these two species was 1.5 times higher under warming over the range of prey densities tested (50 to 250 over 24 h). The total predation rate of H. axyridis larvae on a mixture of S. avenae, R. padi and Schizaphis graminum aphid prey was also increased by 1.4 times, but consumption of R. padi aphids was increased while that of S. graminum was decreased under warming.</li> <li>Overall, our results show that global warming could strongly increase pest outbreaks and destabilize biological pest control, which would likely result in accrued yield losses. </li> </ol>

Data and code from: Accounting for unobserved population dynamics and aging error in close-kin mark-recapture assessments

Obtaining robust estimates of population abundance is a central challenge hindering the conservation and management of many threatened and exploited species. Close-kin mark-recapture (CKMR) is a genetics-based approach that has strong potential to improve monitoring of data-limited species by enabling estimates of abundance, survival, and other parameters for populations that are challenging to assess. However, CKMR models have received limited sensitivity testing under realistic population dynamics and sampling scenarios, impeding application of the method in population monitoring programs and stock assessments. Here, we use individual-based simulation to examine how unmodeled population dynamics and aging uncertainty affect the accuracy and precision of CKMR parameter estimates under different sampling strategies. We then present adapted models that correct the biases that arise from model misspecification. Our results demonstrate that a simple base-case CKMR model produces robust estimates of population abundance with stable populations that breed annually; however, if a population trend or non-annual breeding dynamics are present, or if year-specific estimates of abundance are desired, a more complex CKMR model must be constructed. In addition, we show that CKMR can generate reliable abundance estimates for adults from a variety of sampling strategies, including juvenile-focused sampling where adults are never directly observed (and aging error is minimal). Finally, we apply a CKMR model that has been adapted for population growth and intermittent breeding to two decades of genetic data from juvenile lemon sharks (Negaprion brevirostris) in Bimini, Bahamas, to demonstrate how application of CKMR to samples drawn solely from juveniles can contribute to monitoring efforts for highly mobile populations. Overall, this study expands our understanding of the biological factors and sampling decisions that cause bias in CKMR models, identifies key areas for future inquiry, and provides recommendations that can aid biologists in planning and implementing an effective CKMR study, particularly for long-lived data-limited species.

Genetic admixture between Central European and Alpine wolf populations

The recovery and expansion of formerly isolated wolf populations in Europe raise questions about the nature of their interactions and future consequences for population viability and conservation. Will fragmented populations fuse or maintain a certain level of isolation with migration? Central Europe is suitable for obtaining empirical data in this field as it represents a "crossroad" with the potential for contact among several phylogeographic lineages. In this study, non-invasive genetic samples obtained during population monitoring in the Bohemian and Bavarian Forest (BBF) mountain ranges in the Czech Republic and Germany (Bohemian Massif) were analysed at different neutral markers including mitochondrial sequence, nuclear autosomal microsatellites and gonosomal sex markers. Resultant genetic profiles were compared with reference data to study population ancestry. Both cluster analyses of microsatellite genotypes and syntopic occurrence of haplotypes HW01 and HW22 showed genetic admixture between Central European and Alpine populations. This represents secondary contact and interbreeding of formerly allopatric populations with different phylogeographic histories and distant expansion centres in different biomes in the Baltic region versus the Apennine peninsula and Alps. Moreover, the study describes the founding event and genealogy of this admixed deme, inhabiting intermediate environmental conditions compared to parental forms, and emphasises the role of protected areas as stepping stones in the range recolonization process in endangered large mammals.

Contrasting patterns of sequence variation in steelhead populations reflect distinct evolutionary processes

Multiple evolutionary processes influence genome‐wide allele frequencies and quantifying effects of genetic drift, and multiple forms of selection remain challenging in natural populations. Here, we investigate variation at major effect loci in contrast to patterns of neutral drift across a wide collection of steelhead (Oncorhynchus mykiss) populations that have declined in abundance due to anthropogenic impacts. Whole‐genome resequencing of 74 populations of steelhead revealed genome‐wide patterns (~8 million SNPs) consistent with expected neutral population structure. However, allelic variation at major effect loci associated with adult migration timing (chromosome 28: GREB1L/ROCK1) and age at maturity (chromosome 25: SIX6) reflected how selection has acted on phenotypic variation in contrast with neutral structure. Variation at major effect loci was influenced by evolutionary processes with differing signals between the strongly divergent Coastal and Inland lineages, while allele frequencies within and among populations within the Inland lineage have been driven by local natural selection as well as recent anthropogenic influences. Recent anthropogenic effects appeared to have influenced the frequency of major effect alleles including artificial selection for specific traits in hatchery stocks with subsequent gene flow into natural populations. Selection from environmental factors at various scales has also likely influenced variation for major effect alleles. These results reveal evolutionary mechanisms that influence allele frequencies at major effect loci that are critical for conservation of phenotypic traits and life history variation of this protected species.

Lemur population density in Sahamalaza-Iles Radama National Park, Madagascar

The clearing and fragmentation of tropical forest is the single biggest threat to primate populations who depend on this habitat for survival. In contrast to primates that live in continuous, undisturbed forests, primate communities of fragmented forests need to adapt to decreased food availability and increased inter- and intraspecific competition typical of these degraded and anthropogenically disturbed habitats. Some primate species are highly sensitive to habitat fragmentation, whilst other species can adapt and even thrive in fragmented and degraded forests. Here, we assessed how forest fragmentation and associated edge-effects impact the population density of four species of nocturnal lemur in the Sahamalaza-Iles Radama National Park, North West Madagascar. We conducted 118 transect walks over a three-year period covering a total distance of 107 km to collect encounter rate (N/km) and population density (N/Ha) data for each species, which we then compared between the edge and core areas of a continuous forest and a fragmented forest. Our results were highly species-specific, with the population densities of two species (Lepilemur sahamalaza and Microcebus sambiranensis) increasing in edge and fragmented habitat, whilst we observed the opposite for Cheirogaleus medius. Mirza zaza density appeared consistent between the continuous and fragmented forest and in both edge and core areas. We also found evidence of species-specific population density relationships with fragment size, core area, and fragment shape; however, further work is needed to support these findings. This study demonstrates that some nocturnal lemurs can adapt to degraded habitats and thrive within fragmented forests, whilst other species are less capable of doing so.

Diet-induced plasticity of life-history traits and gene expression in outbred Drosophila melanogaster population

Food is fundamental for the survival of organisms, governing growth, maintenance, and reproduction through the provision of essential macronutrients. However, access to food with optimum macronutrient composition, which will maximize the evolutionary fitness of an organism, is not always guaranteed. This leads to dietary mismatches with potential impacts on organismal performance. To understand the consequences of such dietary mismatches, we examined the effects of isocaloric diets varying in macronutrient composition on eight key organismal traits spanning across the lifespan of a large outbred Drosophila melanogaster population (n ~ 2500). Our findings reveal that carbohydrate-reduced isocaloric diets correlates to accelerated pre-adult development and boosts reproductive output without impacting pre-adult viability and body size. Conversely, an elevated dietary carbohydrate content correlated to reduced lifespan in flies, evidenced by accelerated functional senescence including compromised locomotor activity and deteriorating gut integrity. Furthermore, transcriptomic analysis indicated a substantial difference in gene regulatory landscapes between flies subject to high carbohydrate vs high protein diet, with elevated protein levels indicating transcriptomes primed for reduced synthesis of fatty acids. Taken together, our study helps advance our understanding of the effect of macronutrient composition on life history traits and their interrelations, offering critical insights into potential adaptive strategies that organisms might adopt against the continual dietary imbalances prevalent in the rapidly evolving environment.

Population genetics of the Four Corners potato (Solanum jamesii)

The domestication of wild plant species can begin with gathering and transport of propagules by Indigenous peoples. The effect on genomic composition, especially in clonal, self-incompatible perennials would be instantaneous and drastic with respect to new, anthropogenic populations subsequently established. Populations of the Four Corners potato, Solanum jamesii Torr., associated with archaeological sites in Utah and northern Arizona are unable to produce seeds and fruits unless crossed with non-archaeological populations. Presumably, founder events reduced genetic diversity and mating capability when tubers were transported and established in ancient gardens. Herein genetic sequencing (GBS) data is used to further examine the hypothesis of domestication in this culturally significant species by sampling 25 archaeological and non-archaeological populations. Archaeological populations from Utah, Colorado, and northern Arizona have lower levels of polymorphic loci, unique alleles, and heterozygosity than non-archaeological populations from the Mogollon Region of central Arizona and New Mexico. Principle components analysis, Fst values, and structure analysis revealed that genetic relationships among archaeological populations did not correspond to geographic proximity. Populations near Escalante, Utah were either derived from those found on the Mogollon Rim (400 km south) or related to those in Bears Ears (178 km east). Populations in Chaco Canyon are also similar to Escalante, but those in Mesa Verde, Chimney Rock, and El Morro have affinities to southern New Mexico and Texas. Movement of tubers from the Mogollon Region may have occurred many times and in multiple directions during the past, resulting in the complex genetic patterns seen in these populations from across the Four Corners Region.

Phenotypic traits of 17 populations of Spartina alterniflora in China

Understanding the ecological and evolutionary processes that underlie phenotypic and genetic variation among invasive plant populations and the capacity of such populations to colonize a broad range of environments is a major goal in ecology. Rapid adaptation to local environmental conditions often leads to latitudinal clines in both phenotypes and genotypes of invasive plant species. Previous studies suggest that natural selection influenced a latitudinal cline in phenotypic traits of the invasive plant Spartina alterniflora in China. However, little is understood of the relationship between genetic and phenotypic differentiation and environmental factors among S. alterniflora populations. Here, we studied whether S. alterniflora exhibits a latitudinal cline in genetic diversity across the east coast of China and whether genetic and phenotypic differentiation among populations were correlated with environmental factors. The Restriction-site Associated DNA (RAD-seq) sequencing was used to obtained genomic information of 17 populations of S. alterniflora in China. A redundancy analysis (RDA) was performed to assess whether environmental variables were corelated with genetic and phenotypic differentiation among the populations. A univariate environmental association analysis (implemented through Latent Factor Mixed Model; LFMM) and a principal component analysis (PCAdapt) were used to test for signature of local adaptation. A total of 3, 310 SNPs showed a clear genetic structure among populations in three climatic regions (northern, mid-latitude and southern). Positive correlations between genetic differentiation and variation in reproductive characteristics of S. alterniflora were revealed, suggesting that sexual reproduction traits might be stable and genetically heritable. Outlier loci that were identified by both PCAdapt and LFMM methods were significantly correlated to soil phosphorus content, soil salinity, and precipitation. These results provide evidence of molecular signatures of local adaptation of S. alterniflora and suggest that rapid adaptive evolution may facilitate invasiveness of S. alterniflora in China.

Data for: Coherent long-term body-size responses across all Northwest Atlantic herring populations to warming and environmental change despite contrasting harvest and ecological factors

Body size is a key component of individual fitness and an important factor in the structure and functioning of populations and ecosystems. Disentangling the effects of environmental change, harvest, and intra- and inter-specific trophic effects on body size remains challenging for populations in the wild. Herring in the Northwest Atlantic provide a strong basis for evaluating hypotheses related to these drivers given that they have experienced significant warming and harvest over the past century, while also having been exposed to a wide range of other selective constraints across their range. Using data on mean length-at-age 4 for the sixteen principal populations over a period of 53 cohorts (1962-2014), we fitted a series of empirical models for temporal and between-population variation in the response to changes in sea surface temperature. We find evidence for a unified cross-population response in the form of a parabolic function according to which populations in naturally warmer environments have responded more negatively to increasing temperature compared with those in colder locations. Temporal variation in residuals from this function was highly coherent among populations, further suggesting a common response to a large-scale environmental driver. The synchrony observed in this study system, despite strong differences in harvest and ecological histories among populations and over time, clearly indicates a dominant role of environmental change on size-at-age in wild populations, in contrast to commonly reported effects of fishing. This finding has important implications for the management of fisheries as it indicates that a key trait associated with population productivity may be under considerably less short-term management control than currently assumed. Our study, overall, illustrates the need for a comparative approach within species for inferences concerning the many possible effects on body size of natural and anthropogenic drivers in the wild.

Data from: Metabarcoding of fecal pellets in wild muskox populations reveals negative relationships between microbiome and diet alpha diversity

Microbiome diversity and diet composition concomitantly influence species health, fitness, immunity, and digestion. In environments where diet varies spatially and temporally, microbiome plasticity may promote rapid host adaptation to available resources. For northern ungulates in particular, metabarcoding of noninvasively collected fecal pellets presents unprecedented insights into their diverse ecological requirements and niches by clarifying the interrelationships of microbiomes, key to deriving nutrients, in context of altered forage availability in changing climates. Muskoxen (Ovibos moschatus) are Arctic-adapted species that experience fluctuating qualities and quantities of vegetation. Geography and seasonality have been noted to influence microbiome composition and diversity in muskoxen, yet it is unclear how their microbiomes intersect with diet. Following observations from other species, we hypothesized increasing diet diversity would result in higher microbiome diversity in muskoxen. We assessed diet composition in muskoxen using three common plant metabarcoding markers and explored correlations with microbiome data. Patterns of dietary diversity and composition were not fully concordant among the markers used, yet all reflected the primary consumption of willows and sedges. Individuals with similar diets had more similar microbiomes, yet in contrast to most literature, yielded negative relationships between microbiome and diet alpha diversity. This negative correlation may reflect the unique capacities of muskoxen to survive solely on high-fiber Arctic forage and provide insight into their resiliency to exploit changing dietary resources in a rapidly warming Arctic altering vegetation diversity.

Data from: Distribution, population dynamics and potential impacts of the invasive snail, Tarebia granifera in aquatic ecosystems of north-eastern South Africa

Aquatic ecosystems globally have been invaded by molluscs. Tarebia granifera is a highly successful invader, often becoming the dominant aquatic invertebrate species in an invaded ecosystem. Resultingly, it has been suggested that T. granifera may have severe negative impacts on these invaded ecosystems. Limited information is available regarding the population structures and densities of T. granifera, particularly in invaded countries such as South Africa, and information on this could assist in developing management and control strategies for this invasive species. The aim of the present study was to assess the current distribution, densities, and population structures of T. granifera in invaded habitats on the Limpopo and Phongolo River systems, South Africa. This was accomplished by collecting aquatic benthic molluscs from sites across these systems. Water quality parameters were measured at each site and water samples collected for chemical nutrient analyses. The density of snails was determined for each site and the population size and structure as well as birth rate was calculated for T. granifera. Tarebia granifera was found to be the dominant molluscan species in habitats where it was present and all size classes from new-born to mature adults were found throughout at some of the highest densities globally. Worryingly, native molluscan species, were often absent or in much lower densities than reported in literature at sites where T. granifera was present, suggesting a negative effect on the native molluscan density and diversity. Contrary to most previous studies, there were no significant correlations between T. granifera and the selected water quality parameters. Higher densities and new-born recruitment of T. granifera were observed in the spring than autumn, likely in response to shifts in environmental conditions. This study provides crucial insights into the population structure and dynamics of T. granifera in invaded habitats, particularly for relatively newly invaded regions such as southern Africa.

Body mass, temperature, and pathogen intensity differentially affect critical thermal maxima and their population-level variation in a solitary bee

Climate change presents a major threat to species distribution and persistence. Understanding what abiotic or biotic factors influence the thermal tolerances of natural populations is critical to assessing their vulnerability under rapidly changing thermal regimes. This study evaluates how body mass, local climate, and pathogen intensity influence heat tolerance and its population-level variation (SD) among individuals of the solitary bee Xenoglossa pruinosa. We assess the sex-specific relationships between these factors and heat tolerance given the differences in size between sexes and the ground-nesting behavior of the females. We collected X. pruinosa individuals from fourteen sites across Pennsylvania, USA that varied in mean temperature, precipitation, and soil texture. We measured the critical thermal maxima (CTmax) of X. pruinosa individuals as our proxy for heat tolerance, and used quantitative PCR to determine relative intensities of three parasite groups—trypanosomes, Spiroplasma apis (mollicute bacteria), and Vairimorpha apis (microsporidian). While there was no difference in CTmax between the sexes, we found that CTmax increased significantly with body mass, and that this relationship was stronger for males than for females. Air temperature, precipitation, and soil texture did not predict mean CTmax for either sex. However, population-level variation in CTmax was strongly and negatively correlated with air temperature, which suggests that temperature is acting as an environmental filter. Of the parasites screened, only trypanosome intensity correlated with heat tolerance. Specifically, trypanosome intensity negatively correlated with the CTmax of female X. pruinosa but not males. Our results highlight the importance of considering size, sex, and infection status when evaluating thermal tolerance traits. Importantly, this study reveals the need to evaluate trends in the variation of heat tolerance within and between populations, and consider implications of reduced variation in heat tolerance for the persistence of ectotherms in future climate conditions.

opencc-zeroMar 2024View details →

Data for: Climate warming and projected loss of thermal habitat volume in lake populations of brook trout

We applied an ensemble of climate warming models and the seasonal temperature profile model for lakes (STM) to assess changes in brook trout thermal habitat volume (THV) among lakes (N=100) within a large, protected area under two climate warming scenarios, RCP 4.5 and RCP 8.5. Brook trout thermal habitat was defined as 9-17°C. Climate warming projections for the balance of this century, regardless of RCP category, will result in the loss of brook trout habitat in lakes that range widely in size. THV loss will be most extensive in lakes that are relatively shallow given their surface area. By 2071-2100 under RCP 4.5, the 90th percentile of THV loss = 31% vs. 63% under RCP 8.5. By the century's end under RCP 8.5, the protected area landscape will be a matrix of lakes with some serving as climate refugia (with reduced THV) and others having severe reductions in THV (>90th percentile THV loss).