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176 results for “climatic gradient”
Soil respiration measurements along climate and black spruce productivity gradients in interior Alaska
Soil respiration measurements were made using an infrared gas analyzer (IRGA; EGM-4 gas analyzer, PP Systems, Haverhill, MA) with a dynamic soil respiration chamber (SRC-2, PP Systems). Respiration collars (18) were randomly located on three 20 x 20 m sampling grids (separate from WSOC collection) at each site. The respiration collars (10.2 cm diameter schedule 40 polyvinyl chloride) were inserted to a depth of 2.5 cm at least 1 week prior to initial measurements and were left in place for the duration of the experiment. Care was taken to ensure that the collars remained at the same depth throughout the measurement period. All vascular plants were removed from the collars prior to measuring. Measurements were made approximately bi-weekly at each site, from May through September in 2004 (n = 5 or 6). A portable thermometer was used to measure soil temperature at 10 cm below the surface concurrently with soil respiration measured at each collar. Changes in collar-specific air volumes (caused by changes in microtopography and the presence of moss) were measured directly through use of the ideal gas law by injecting 25 cm-3 of 3500 mg m-3 CO2 into the soil respiration chamber and measuring the subsequent dilution of CO2 concentration with the IRGA. All flux values have been adjusted for these collar specific volumes.
Data from: Contrasting patterns of local adaptation along climatic gradients between a sympatric parasitic and autotrophic tree species
<p>Sympatric tree species are subject to similar climatic drivers, posing a question as to whether they display comparable adaptive responses. However, no study has explicitly examined local adaptation of co-occurring parasitic and autotrophic plant species to the abiotic environment. Here we test the hypotheses that a generalist parasitic tree would display a weaker signal of selection and genomic variation would associate with fewer climatic variables (particularly precipitation) but have similar spatial patterns to a sympatric autotrophic tree species. To test these hypotheses, we collected samples from 17 sites across the range of two tree species, the hemi-parasite <i>Nuytsia floribunda</i> (<i>n</i>=264) and sympatric autotroph<i> Melaleuca rhaphiophylla </i>(<i>n</i>=272). We obtained 5,531 high-quality genome-wide single nucleotide polymorphisms (SNPs) for <i>M. rhaphiophylla</i> and 6,727 SNPs for <i>N. floribunda</i> using DArTseq™ genome scan technology. Population differentiation and environmental association approaches were used to identify signals of selection. Generalized dissimilarly modelling was used to detect climatic and spatial patterns of local adaptation across climatic gradients. Overall, 322 SNPs were identified as putatively adaptive for the autotroph, while only 57 SNPs were identified for the parasitic species. We found genomic variation to associate with different sets of bioclimatic variables for each species, with precipitation relatively less important for the parasite. Spatial patterns of predicted adaptive variability were different and indicate that co-occurring species with disparate life history traits may not respond equally to selective pressures (i.e. temperature and precipitation). Together, these findings provide insight into local adaptation of sympatric parasitic and autotrophic tree species to abiotic environments.</p>
Data from: Marine latitudinal diversity gradients, niche conservatism, and out of the tropics and Arctic: climatic sensitivity of small organisms
<ul> <li>Aim</li> </ul> <p>The latitudinal diversity gradient (LDG) is a consequence of evolutionary and ecological mechanisms acting over long history, and thus is best investigated with organisms that have rich fossil records. However, combined neontological-paleontological investigations are mostly limited to large, shelled invertebrates, which keeps our mechanistic understanding of LDGs in its infancy. This paper aims to describe the modern meiobenthic ostracod LDG and to explore the possible controlling factors and the evolutionary mechanisms of this large-scale biodiversity pattern.</p> <ul> <li>Location</li> </ul> <p>Present-day Western North Atlantic</p> <ul> <li>Taxon</li> </ul> <p>Ostracoda</p> <ul> <li>Methods</li> </ul> <p>We compiled census data from ostracods living in shallow marine environments of the western North Atlantic Ocean. Using these data, we documented the marine LDG with multiple metrics of alpha, beta (nestedness and turnover), and gamma diversity, and we tested whether macroecological patterns could be governed by different environmental factors, including temperature, salinity, dissolved oxygen, pH and primary productivity. We also explored the geologic age distribution of ostracod genera to investigate the evolutionary mechanisms underpinning the LDG.</p> <ul> <li>Results</li> </ul> <p>Our results show that temperature and climatic niche conservatism are important in setting LDGs of these small, poorly-dispersing organisms. We also found evidence for some dispersal-driven spatial dynamics in the ostracod LDG. Compared to patterns observed in marine bivalves, however, dispersal dynamics were weaker and they were bi-directional, rather than following the "out-of-the-tropics" model.</p> <ul> <li>Main Conclusions</li> </ul> <p>Our detailed analyses revealed that meiobenthic organisms, which comprise two-thirds of marine diversity, do not always follow the same rules as larger, better-studied organisms. Our findings suggest that the under-studied majority of biodiversity may be more sensitive to climate than are well-studied, large organisms. This implies that the impacts of ongoing Anthropocene climatic change on marine ecosystems may be much more serious than presently thought.</p>
Data from: Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient
Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthropogenic effects. We addressed this goal by measuring plant elemental (C, N, P and K) responses to eutrophication and vertebrate herbivore exclusion at eighteen sites on six continents. Across sites, climate and atmospheric N deposition emerged as strong predictors of plot‐level tissue nutrients, mediated by biomass and plant chemistry. Within sites, fertilization increased total plant nutrient pools, but results were contingent on soil fertility and the proportion of grass biomass relative to other functional types. Total plant nutrient pools diverged strongly in response to herbivore exclusion when fertilized; responses were largest in ungrazed plots at low rainfall, whereas herbivore grazing dampened the plant community nutrient responses to fertilization. Our study highlights (1) the importance of climate in determining plant nutrient concentrations mediated through effects on plant biomass, (2) that eutrophication affects grassland nutrient pools via both soil and atmospheric pathways and (3) that interactions among soils, herbivores and eutrophication drive plant nutrient responses at small scales, especially at water‐limited sites.
Data from: Patterns of divergence across the geographic and genomic landscape of a butterfly hybrid zone associated with a climatic gradient
Hybrid zones are a valuable tool for studying the process of speciation and for identifying the genomic regions undergoing divergence and the ecological (extrinsic) and non-ecological (intrinsic) factors involved. Here, we explored the genomic and geographic landscape of divergence in a hybrid zone between Papilio glaucus and Papilio canadensis. Using a genome scan of 28,417 ddRAD SNPs, we identified genomic regions under possible selection and examined their distribution in the context of previously identified candidate genes for ecological adaptations. We showed that differentiation was genome-wide, including multiple candidate genes for ecological adaptations, particularly those involved in seasonal adaptation and host plant detoxification. The Z-chromosome and four autosomes showed a disproportionate amount of differentiation, suggesting genes on these chromosomes play a potential role in reproductive isolation. Cline analyses of significantly differentiated genomic SNPs, and of species diagnostic genetic markers, showed a high degree of geographic coincidence (81%) and concordance (80%) and were associated with the geographic distribution of a climate-mediated developmental threshold (length of the growing season). A relatively large proportion (1.3%) of the outliers for divergent selection were not associated with candidate genes for ecological adaptations and may reflect the presence of previously unrecognized intrinsic barriers between these species. These results suggest that exogenous (climate-mediated) and endogenous (unknown) clines may have become coupled and act together to reinforce reproductive isolation. This approach of assessing divergence across both the genomic and geographic landscape can provide insight about the interplay between the genetic architecture of reproductive isolation and endogenous and exogenous selection.
Data from: Influence of a climatic gradient on genetic exchange between two oak species
Premise of the study. In plant groups with limited intrinsic barriers to gene flow, it is thought that environmental conditions can modulate interspecific genetic exchange. Oaks are known for limited barriers to gene flow among closely related species. Here, we use Quercus as a living laboratory in which to pursue a fundamental question in plant evolution: do environmental gradients restrict or promote genetic exchange between species? Methods. We focused on two North American oaks, the rare Q. dumosa and the widespread Q. berberidifolia. We sampled intensively along a contact zone in California. We sequenced restriction site associated DNA markers and measured vegetative phenotype. We tested for genetic exchange, the association with climate, and the effect on phenotype. Key results. There is evidence for genetic exchange between the species. Admixed plants are found in areas of intermediate climate, while less admixed plants are found at the extremes of the climatic gradient. Genetic and phenotypic patterns are out of phase in the zone of contact; some plants display the phenotype of one species but are genetically associated with another. Conclusions. Our results support the hypothesis that a strong climatic gradient can promote genetic exchange between species. The overall weak correlation between genotype and phenotype in the contact zone between the species suggests that genetic exchange can lead to the breakdown of trait combinations used to define species. This incongruency predicts ongoing problems for conservation of Q. dumosa, with implications for conservation of other oaks. Please be aware that if you ask to have your user record removed, we will retain your name in the records concerning manuscripts for which you were an author, reviewer, or editor. In compliance with data protection regulations, you may request that we remove your personal registration details at any time. (Use the following URL: https://www.editorialmanager.com/ajb/login.asp?a=r) Please contact the publication office if you have any questions.
Temporal and spatial evaluation of satellite-based rainfall estimates across the complex topographical and climatic gradients of Chile (datasets)
<p>This file contains the <strong>dataset</strong> (both raw observed precipitation data and figures obtained as output of the analysis) accompanying the manuscript '<strong>hess-2016-453'</strong> submitted to the HESS journal (http://www.hydrology-and-earth-system-sciences.net/).</p> <p> </p> <p><strong>Title</strong>: "Temporal and spatial evaluation of satellite-based rainfall estimates across the complex topographical and climatic gradients of Chile"</p> <p> </p> <p><strong>Abstract</strong></p> <p>Accurate representation of the real spatio-temporal variability of catchment rainfall inputs is currently severely limited. Moreover, spatially interpolated catchment precipitation is subject to large uncertainties, particularly in developing countries and regions which are difficult to access (e.g., high elevation zones). Recently, satellite-based rainfall estimates (SRE) provide an unprecedented opportunity for a wide range of hydrological applications, from water resources modelling to monitoring of extreme events such as droughts and floods. </p> <p>This study attempts to exhaustively evaluate -for the first time- the suitability of seven state-of-the-art SRE products (TMPA 3B42v7, CHIRPSv2, CMORPH, PERSIANN-CDR, PERSIAN-CCS-adj, MSWEPv1.1 and PGFv3) over the complex topography and diverse climatic gradients of Chile. Different temporal scales (daily, monthly, seasonal, annual) are used in a point to-pixel comparison between precipitation time series measured at 366 stations (from sea level to 4600 m a.s.l. in the Andean Plateau) and the corresponding grid cell of each SRE. The modified Kling-Gupta efficiency was used to identify possible sources of systematic errors in each SRE. In addition, several categorical indices were used to assess the ability of each SRE to correctly identify different precipitation intensities.</p> <p><br> Results revealed that most SRE products performed better for the humid South (36.4-43.7ºS) and Central Chile (32.18-36.4ºS), in particular at low- and mid-elevation zones (0-1000 m a.s.l.) compared to the arid northern regions and the Far South. Seasonally, all products performed best during the wet seasons (MAM-JJA) compared to summer (DJF) and autumn (SON). In addition, all SREs were able to correctly identify the occurrence of no rain events, but they presented a low skill in classifying precipitation intensities during rainy days. Overall, PGFv3 exhibited the best performance everywhere and for all time scales, which can be clearly attributed to its bias-correction procedure using 213 stations from Chile. Good results were also obtained by CHIRPSv2, TMPA 3B42v7 and MSWEPv1.1, while CMORPH, PERSIANN-CDR and PERSIANN-CCS-adj were not able to represent observed rainfall. While PGFv3 (currently available up to 2010) might be used in Chile for historical analyses and calibration of hydrological models, the high spatial resolution, low latency and long data records of CHIRPS and TMPA 3B42v7 (in transition to IMERG) show promising potential to be used in meteorological studies and water resources assessments. We finally conclude that despite improvements of most SRE products, a site-specific calibration is still needed before any use in catchment-scale hydrological studies.</p>
Temporal and spatial evaluation of satellite-based rainfall estimates across the complex topographical and climatic gradients of Chile (supplementary material)
<p>This file contains the <strong>Supplement</strong> (both raw observed precipitation data and figures obtained as output of the analysis) accompanying the manuscript '<strong>hess-2016-453'</strong> submitted to the HESS journal (http://www.hydrology-and-earth-system-sciences.net/).</p> <p><strong>Title</strong>: "Temporal and spatial evaluation of satellite-based rainfall estimates across the complex topographical and climatic gradients of Chile"</p> <p> </p> <p><strong>Abstract</strong></p> <p>Accurate representation of the real spatio-temporal variability of catchment rainfall inputs is currently severely limited. Moreover, spatially interpolated catchment precipitation is subject to large uncertainties, particularly in developing countries and regions which are difficult to access. Recently, satellite-based rainfall estimates (SRE) provide an unprecedented opportunity for a wide range of hydrological applications, from water resources modelling to monitoring of extreme events such as droughts and floods.</p> <p>This study attempts to exhaustively evaluate -for the first time- the suitability of seven state-of-the-art SRE products (TMPA 3B42v7, CHIRPSv2, CMORPH, PERSIANN-CDR, PERSIAN-CCS-adj, MSWEPv1.1 and PGFv3) over the complex topography and diverse climatic gradients of Chile. Different temporal scales (daily, monthly, seasonal, annual) are used in a point-to-pixel comparison between precipitation time series measured at 366 stations (from sea level to 4600 m a.s.l. in the Andean Plateau) and the corresponding grid cell of each SRE (rescaled to a 0.25° grid if necessary). The modified Kling-Gupta efficiency was used to identify possible sources of systematic errors in each SRE. In addition, five categorical indices (PC, POD, FAR, ETS, fBIAS) were used to assess the ability of each SRE to correctly identify different precipitation intensities.</p> <p>Results revealed that most SRE products performed better for the humid South (36.4-43.7°S) and Central Chile (32.18-36.4°S), in particular at low- and mid-elevation zones (0-1000 m a.s.l.) compared to the arid northern regions and the Far South. Seasonally, all products performed best during the wet seasons autumn and winter (MAM-JJA) compared to summer (DJF) and spring (SON). In addition, all SREs were able to correctly identify the occurrence of no rain events, but they presented a low skill in classifying precipitation intensities during rainy days. Overall, PGFv3 exhibited the best performance everywhere and for all time scales, which can be clearly attributed to its bias-correction procedure using 217 stations from Chile. Good results were also obtained by the research products CHIRPSv2, TMPA 3B42v7 and MSWEPv1.1,while CMORPH, PERSIANN-CDR and the real-time PERSIANN-CCS-adj were less skillful in representing observed rainfall. While PGFv3 (currently available up to 2010) might be used in Chile for historical analyses and calibration of hydrological models, the high spatial resolution, low latency and long data records of CHIRPS and TMPA 3B42v7 (in transition to IMERG) show promising potential to be used in meteorological studies and water resources assessments. We finally conclude that despite improvements of most SRE products, a site-specific assessment is still needed before any use in catchment-scale hydrological studies.</p>
Drivers and mechanisms that contribute to microbial β-diversity patterns and range sizes in mountains across a climatic variability gradient
<p>Microbial communities are highly diverse, yet the mechanisms underlying microbial community assembly are not well understood. Janzen's mountain passes hypothesis proposed that climatic barriers and dispersal limitation shape communities to a greater extent in mountains with lower climatic variability and overlap, permitting higher levels of species coexistence. Here, we investigate changes in microbial community dissimilarities, distributional range sizes and ecological processes along elevational gradients in three montane ecosystems representing a climatic variability gradient. We found that climate, climatic variability and spatial distance play dominating roles in affecting microbial β-diversity patterns and range sizes along elevational gradients. Janzen's mountain passes hypothesis can be applied for microbial community assembly: mountains with lower climatic variability and higher climatic difference between elevations exhibited higher β-diversity, higher endemism, lower range sizes, and steeper distance-decay trends. However, microbial communities experience clear climate-driven limited range sizes and dispersal processes and show typical endemic patterns in all mountain ecosystems. Our results emphasize the importance of dispersal and climatic niche processes in shaping montane biodiversity. As a result, changes in climate may significantly impact soil biodiversity in montane ecosystems by altering the effects of dispersal limitation and climatic variability on bacterial and fungal community composition along elevational gradients.</p>
Data from: Tree diversity enhances predation by birds but not by arthropods across climate gradients
<p>Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (<a href="https://www.treedivnet.ugent.be">www.treedivnet.ugent.be</a>; <em>TreeDivNet</em>) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation. We recorded bird and arthropod predation attempts on plasticine caterpillars in monocultures and tree species mixtures. Both tree species richness and temperature increased predation by birds, but not by arthropods. Furthermore, the effects of tree species richness on predation were consistent across the studied climatic gradient. Our findings provide evidence that tree diversity strengthens top-down control of insect herbivores by birds, underscoring the need of implementing conservation strategies that safeguard tree diversity to sustain ecosystem services provided by natural enemies in forests.</p>
Data from: Putative climate adaptation in American pikas (Ochotona princeps) is associated with copy number variation across environmental gradients
<p>Improved understanding of the genetic basis of adaptation to climate change is necessary for maintaining global biodiversity moving forward. Studies to date have largely focused on sequence variation, yet there is growing evidence that suggests that changes in genome structure may be an even more significant source of adaptive potential. The American pika (<em>Ochotona princeps</em>) is an alpine specialist that shows some evidence of adaptation to climate along elevational gradients, but previous work has been limited to single nucleotide polymorphism (SNP)-based analyses within a fraction of the species range. Here, we investigated the role of copy number variation underlying patterns of local adaptation in the American pika using genome-wide data previously collected across the entire species range. We identified 37-193 putative copy number variants (CNVs) associated with environmental variation (temperature, precipitation, solar radiation) within each of the six major American pika lineages, with patterns of divergence largely following elevational and latitudinal gradients. Genes associated (<em>n</em>=158) with independent annotations across lineages, variables, and/or CNVs had functions related to mitochondrial structure/function, immune response, hypoxia, olfaction, and DNA repair, some of which have been previously linked to putative high elevation and/or climate adaptation that may serve as important targets in future studies.</p>
Signatures of natural selection in a foundation tree along Mediterranean climatic gradients
<p>Temperature and precipitation regimes are rapidly changing, resulting in forest dieback and extinction events, particularly in Mediterranean-type climates (MTC). Forest management that enhance forests' resilience is urgently required, however adaptation to climates in heterogeneous landscapes with multiple selection pressures is complex. For widespread trees in MTC we hypothesized that: patterns of local adaptation are associated with climate; precipitation is a stronger factor of adaptation than temperature; functionally related genes show similar signatures of adaptation; and adaptive variants are independently sorting across the landscape. We sampled 28 populations across the geographic distribution of Eucalyptus marginata (jarrah), in South-west Western Australia, and obtained 13,534 independent single nucleotide polymorphic (SNP) markers across the genome. Three genotype-association analyses that employ different ways of correcting population structure were used to identify putatively adapted SNPs associated with independent climate variables. While overall levels of population differentiation were low (<i>F</i><sub>ST</sub> = 0.04), environmental association analyses found a total of 2,336 unique SNPs associated with temperature and precipitation variables, with 1,440 SNPs annotated to genic regions. Considerable allelic turnover was identified for SNPs associated with temperature seasonality and mean precipitation of the warmest quarter, suggesting that both temperature and precipitation are important factors in adaptation. SNPs with similar gene functions had analogous allelic turnover along climate gradients, while SNPs among temperature and precipitation variables had uncorrelated patterns of adaptation. These contrasting patterns provide evidence that there may be standing genomic variation adapted to current climate gradients, providing the basis for adaptive management strategies to bolster forest resilience in the future.</p>
Divergent climate change effects on widespread dryland plant communities driven by climatic and ecohydrological gradients
<p><span>Plant community response to climate change will be influenced by individual plant responses that emerge from competition for limiting resources that fluctuate through time and vary across space. Projecting these responses requires an approach that integrates </span><span>environmental conditions and species interactions that result from future climatic variability. Dryland plant communities are being substantially affected by climate change because their structure and function are closely tied to precipitation and temperature, yet impacts vary substantially due to environmental heterogeneity, especially in topographically complex regions. Here, we quantified the effects of climate change on big sagebrush (<em>Artemisia tridentata </em>Nutt.) plant communities that span </span><span>76 million ha </span><span>in the western United States. We used an individual-based plant simulation model that represents intra- and inter-specific competition for water availability, which is represented by a process-based soil water balance model. For dominant plant functional types, we quantified changes in biomass and characterized agreement among 52 future climate scenarios. We then used a multivariate matching algorithm to generate fine-scale interpolated surfaces of functional type biomass for our study area. </span>Results suggest geographically divergent responses of big sagebrush to climate change (changes in biomass of -20% to +27%), declines in perennial C<sub>3</sub> grass and perennial forb biomass in most sites, and widespread, consistent, and sometimes large increases in perennial C<sub>4</sub> grasses. The largest declines in big sagebrush, perennial C<sub>3</sub> grass and perennial forb biomass were simulated in warm, dry sites. In contrast, we simulated no change or increases in functional type biomass in cold, moist sites. There was high agreement among climate scenarios on climate change impacts to functional type biomass, except for big sagebrush. Collectively, these results suggest divergent responses to warming in moisture-limited vs. temperature-limited sites and potential shifts in the relative importance of some of the dominant functional types that result from competition for limiting resources.</p>
Thermal performance of seaweeds and seagrasses across a regional climate gradient
<p><span>Comparative patterns in thermal performance between populations have fundamental implications for a species thermal sensitivity to warming and extreme events. Despite this, within-species variation in thermal performance is seldom measured. Here we compare thermal performance between-species variation within communities, for two species of seagrass (<i>Posidonia oceanica</i> and <i>Cymodocea nodosa</i>) and two species of seaweed (<i>Padina pavonica</i> and <i>Cystoseira compressa</i>). Experimental populations from four locations spanning approximately 75% of each species global distribution and a 6ºC gradient in summer temperatures were exposed to 10 temperature treatments (15ºC to 36ºC), reflecting median, maximum and future temperatures. Experimental thermal performance displayed the greatest variability between species, with optimal temperatures differing by over 10ºC within the same location. Within-species differences in thermal performance were also important for <i>P. oceanica</i> which displayed large thermal safety margins within cool and warm-edge populations and small safety margins within central populations. Our findings suggest patterns of thermal performance in Mediterranean seagrasses and seaweeds retain deep 'pre-Mediterranean' evolutionary legacies, suggesting marked differences in sensitivity to warming within and between benthic marine communities.</span></p>
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution
<p>Climatologies from the 3 different model simulations performed for the paper published in Paleoceanography (2010, v25, issue 2, <a href="https://doi.org/10.1029/2009PA001809">https://doi.org/10.1029/2009PA001809</a>). This table shows how the names of the simulations provided here relate to the names in the paper:</p> <table align="center"> <caption>Simulation names for cross-referencing</caption> <thead> <tr> <th scope="col">Name of Files</th> <th scope="col">Name in Article</th> </tr> </thead> <tbody> <tr> <td>EPSST_T_85.*.nc</td> <td>Early Pliocene Simulation</td> </tr> <tr> <td>New_MZSST_T_85.*.nc</td> <td>Modern Zonal Simulation</td> </tr> <tr> <td>ctl_85_Kerry.*.nc</td> <td>Modern Control Simulation</td> </tr> </tbody> </table> <p>Additionally the NCL script originally used to create all the figures is included. It is called paleoc_onsetNHG_rev.ncl. The abstract of the paper is below:</p> <p>"During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable to the modern about 2 Myr ago (as estimated on the eastern side of the Pacific). The zonal SST gradient along the equator, virtually nonexistent in the early Pliocene, reached modern values between 1 and 2 Myr ago. Here, we use an atmospheric general circulation model to investigate the relative roles of the changes in the meridional and zonal temperature gradients for the onset of glacial cycles and for Pliocene-Pleistocene climate evolution in general. We show that the increase in the meridional SST gradient reduces air temperature and increases snowfall over most of North America, both factors favorable to ice sheet inception. The impacts of changes in the zonal gradient, while also important over North America, are somewhat weaker than those caused by meridional temperature variations. The establishment of the modern meridional and zonal SST distributions leads to roughly 3.2°C and 0.6°C decreases in global mean temperature, respectively. Changes in the two gradients also have large regional consequences, including aridification of Africa (both gradients) and strengthening of the Indian monsoon (zonal gradient). Ultimately, this study suggests that the growth of Northern Hemisphere ice sheets is a result of the global cooling of Earth's climate since 4 Myr rather than its initial cause. Thus, reproducing the correct changes in the SST distribution is critical for a model to simulate the transition from the warm early Pliocene to a colder Pleistocene climate."</p> <p> </p>
Bamboo climatic tolerances are decoupled from leaf functional traits across an Andean elevation gradient
Widespread changes in temperature and precipitation patterns present plant species with new and combined stresses that affect their performance and distribution. Functional traits are indicators of plant resource use-acquisition strategies and thus they are commonly used to understand the geographic distributions of plant species and species' potential responses to climate change. To date, most studies have targeted a few easy-to-measure leaf traits even though other traits, such as climatic tolerances, could provide valuable information directly related with species' current and future distributions. Here, we measured both leaf functional traits and indices of physiological tolerance to heat (T50) and drought (Cell Membrane Stability) in 28 woody bamboo populations from 22 narrow-ranged species along a > 3000 m elevation gradient in the southern Peruvian Andes. We found that bamboo leaf functional traits remain fairly constant with a combination indicative of an acquisitive strategy (low leaf mass area and high nitrogen per mass) along the elevation gradient, despite drastic changes in environment and fast species turnover. Heat and drought tolerances of bamboos varied widely along the gradient and were negatively correlated to each other. Drought tolerance of bamboo populations was positively related with elevation and with precipitation seasonality while heat tolerance decreased at higher, colder elevations. When analyzed for individuals within each species or for individuals within each elevation, the two metrics of climatic tolerances did not show a consistent relationship, contrasting with the expectation of a potential trade-off between heat and drought tolerance. We also found that the measured leaf functional traits were not good predictors of climatic tolerances. Our results illustrate the diversity and complexity of the relationships between functional strategies and environmental gradients and highlight the limitations of using basic (i.e., "soft") leaf traits to understand plant distributions and climatic tolerances.
Climate disequilibrium of fishes along elevation and latitudinal gradients: implications for climate tracking
<p>Aim: Differences in realized and fundamental thermal niches can reveal how temperature constrains species distributions. Because climate-induced range shifts assume that temperature influences distribution limits (i.e., climate equilibrium assumption), understanding the factors that determine the realized thermal niche of species is critical for understanding their climate tracking abilities.</p> <p>Location: Thermal niches were evaluated for two scales: Globally (n = 95 species) and across the Great Plains – Rocky Mountain region, U.S.A (n = 28 species)</p> <p>Taxon: Marine and freshwater fishes</p> <p>Results: First, freshwater species were not more likely than marine species to underfill their latitudinal cold-edge limit, despite restricted dispersal in freshwater environments from biogeographic barriers. Second, biological traits of dispersal ability were not associated with patterns of overfilling or underfilling along latitudinal gradients, aside from migratory species being more likely to overfill their cold-edge limits. Third, similar biological traits were not associated with freshwater fishes overfilling or underfilling their cold-edge, elevation limit with respect to their cold-edge latitudinal limit. Fourth, 78% of freshwater fish species (22 of 28) were observed underfilling their elevation limit relative to their latitudinal limit.</p> <p>Main conclusions: Our results reveal that the climate equilibrium assumption is not satisfied for half of marine and freshwater fishes along thermal-spatial gradients and is largely unrelated to dispersal and movement. Freshwater fishes appear particularly limited in their distribution potential along elevation gradients, given the strong patterns of elevation underfilling.</p>
Intraspecific trait variation in a dryland tree species corresponds to regional climate gradients
<p><strong>Aim:</strong> Intraspecific trait variation is fundamental to understanding a species' adaptive capacity. Assessing phenotypic variation at different ecological scales is useful for evaluating species' vulnerability to changing environmental conditions. Here we quantify the ecological scale of variation of phenotypic functional traits for a widespread dryland tree species in the western United States, <em>Pinus monophylla</em>, and evaluate the strength of trait-environment relationships across spatial gradients and in response to interannual variability in weather conditions.</p> <p><strong>Location:</strong> Western United States</p> <p><strong>Taxon:</strong> Conifer tree (Pinaceae): <em>Pinus monophylla</em></p> <p><strong>Methods:</strong> Nine reproductive and foliar morphological traits were measured from 23 sampling locations in nine mountain ranges, stratified across broad-scale gradients of precipitation timing and quantity and local gradients of elevation. We partitioned trait variation within and among nested ecological scales (mountain range, site, tree, and tree growth year). We then used multivariate methods to quantify the association between environmental variables and ecological trade-offs associated with both reproductive and foliar traits.</p> <p><strong>Results:</strong> Most variation was explained at the scale of individual trees (18–46%) and between growth years (20–30%), with smaller but variable contributions at the scale of sites (8–25%) and mountain ranges (0–15%). Trait values had low correlation with environmental variables (13%); however, 94% of the trait-environment covariance was explained by two major axes of variation: (1) the drought-stress gradient covarying with reproductive traits, and (2) precipitation patterns covarying with foliar morphology.</p> <p><strong>Main conclusions:</strong> High levels of individual trait variation indicate within-population adaptive capacity. Consistent relationships among range-wide patterns of foliar and reproductive traits and broad-scale climate gradients provide indirect evidence of local adaptation and may inform seed sourcing for restoration or the potential for assisted migration efforts. Quantification of intraspecific trait variation across multiple ecological scales is important for understanding the potential climate change response of dryland tree species.</p>
Spatial and local environmental factors outperform geo-climatic gradients in structuring taxonomically- and traits-based β‐diversity of benthic algae
<p><b>Aim</b>: Understanding the variation in biodiversity and its underlying drivers and mechanisms is a core task in biogeography and ecology. In this study, we examined: i) the relative contributions of species replacement (i.e. turnover) and richness difference (i.e. nestedness) to taxonomically- and traits-based β-diversity of stream benthic algae; ii) whether these two facets of β-diversity are correlated with each other; and iii) the relative contributions of local environmental (e.g. water chemistry, flow velocity, habitat quality), geo-climatic (e.g. land use types, elevation, precipitation), and spatial factors (e.g. using principal coordinates of neighborhood matrices) to the two facets of β-diversity and their components (i.e. total β-diversity, turnover, and nestedness).</p> <p><b>Location</b>: Hun-Tai River Basin, northeastern China</p> <p><b>Taxon</b>: Stream benthic algae</p> <p><b>Methods</b>: A total of 157 sites were sampled. Mantel tests were used to examine the complementarities between the two facets of β-diversity and their components. Distance-based redundancy analysis and variation partitioning were utilized to investigate the relative contributions of local environmental, geo-climatic, and spatial factors to each facet of β-diversity and their components.</p> <p><b>Results</b>: Weak correlations between taxonomically- and traits-based β‐diversity and their components were detected, which indicated complementarity of ecological information. Taxonomically-based total β‐diversity was largely driven by turnover, whereas traits-based total β-diversity was more driven by nestedness. Variation partitioning results indicated that local environmental and spatial factors contributed more than geo-climatic variables to the total explained variation in taxonomically- and traits-based β‐diversity.</p> <p><b>Main conclusions</b>: Our findings highlighted the importance of the different facets of β‐diversity and their decomposition for understanding diversity patterns of benthic algae relative to abiotic factors. A high level of traits-based convergence among benthic algae communities, despite high taxonomic divergence, demonstrated turnover of species with similar biological traits across our study region. Our study provides a traits-based insight into stream benthic algae communities, which was less documented by previous freshwater studies that focused on regions undergoing recovery following human disturbances.</p>
European soil seed bank communities across a climate and land-cover gradient
<p>This is the data set used for the publication <em>Buffering effects of soil seed banks on plant community composition in response to land use and climate</em>, published in the journal<em> Global Ecology and Biogeography</em>.</p> <p><strong>Aim</strong>. Climate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life-history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this.</p> <p><strong>Location</strong>. Europe</p> <p><strong>Time</strong> <strong>period</strong>. 1978 – 2014</p> <p><strong>Major taxa studied</strong>. Flowering plants</p> <p><strong>Methods</strong>. Using a space-for-time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient.</p> <p><strong>Results</strong>. Soil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer.</p> <p><strong>Main conclusions</strong>. High seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be threatened by climate warming. Dormant life-history stages can therefore be important sources of diversity in changing environments, potentially underpinning already observed time-lags in plant community responses to global change. However, as soil seed banks themselves appear, albeit less, vulnerable to the same changes, their potential to buffer change can only be temporary, and major community shifts may still be expected.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.