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opencc-by-4.0Aug 2024View details →

Agronomic, rheological and nutritional phenotypic data of 50 spelt varieties grown at 3 locations in Switzerland during 2 growing seasons (2021-2022)

This dataset contains agronomic, rheological, and nutritional parameters of 50 winter spelt varieties tested during 2 growing seasons (2021-2022) at 3 locations in Switzerland. The dataset has been used to investigate the links between genotype and phenotype of spelt varieties, published in https://doi.org/10.1007/s10681-024-03400-8. The field trials were performed under the Swiss Extenso (low input) conditions, conducted by Agroscope and DSP, and under organic conditions, performed by GZPK.   <h3>Methods </h3> Field trials  <div>Field trials were set up over the course of two growing seasons – 2020/2021, 2021/2022 – in three sites across the Swiss Central Plateau. The experimental sites were located in Changins (46°19′ N 6°14′ E, 455m a.s.l), Delley (46°55′ N 6°58′ E, 494m a.s.l) and Feldbach (47°14'24.00" N, 8°47'9.60" E, 410m a.s.l.).</div> <div>Each variety was grown in a plot of 7.1 m2 (1.5 m*4.7 m) in Changins and Delley, and 4.5 m2 (1.5 m*3 m) in Feldbach. We replicated the experiment three times per location. At each site, we used a complete randomized block design, with plots being randomized within each block. Density of sowing was 180 spikelets/m2. Plots were sowed mechanically each autumn. In Changins and Delley, the plots were mechanically fertilized with 100 kg N/ha (ammonium nitrate), applied in two splits (60 at heading stage—40 at flowering stage). In Feldbach, the fields were treated organically, and therefore no synthetic fertilizer was applied.</div> <div> </div> <div> </div> <div>Agronomic and morphological characteristics </div> <div> For each plot, we recorded the heading date as the day of the year, in which 50% of the ears of the plot had fully emerged from the flag leaf. Once the plants and ears were fully developed, plant height was measured in each plot, by taking the average height in centimeters from the ground to the top of five random ears, excluding awns. At maturity, we harvested each plot with a combine harvester (Zürn 150, Schontal-Westernhausen, Switzerland). The harvested grains were weighed first, dehusked, sorted and cleaned with a sieve cleaner, and then weighted again. We measured specific weight and water content using a Dickey–John machine (GAC 2100). Grain yield was subsequently standardized to 15% of humidity. Protein content (%) was measured at the plot level with a near-infrared instrument (ProxiMate™, Büchi instruments). Thousand kernel weight (TKW, g), as well as kernel length and width (mm), were measured at the plot level with a Marvin seed analyzer (GTA Sensorik, Neubrandenburg, Germany). Additional measurements in Changins: we computed harvest index for each plot by cutting 30 individual culms just before harvest. Plants were cut just above the ground, oven-dried for 3 days at 80 °C and then weighed. We then threshed, dehusked, sieved and weighed the obtained grains. The harvest index was computed by taking the ratio of grain mass over total mass.   Rheological characteristics  </div> <div> At all sites, Zeleny sedimentation value (mL) was assessed based on the International Association for Cereal Science and Technology standard method 116/1.The analyses were performed by the analytical laboratory of DSP, Delley, at the variety level for each site—i.e., grains from the three replicates per site were pooled together and subsequently milled. Additional measurements in Changins were done for each variety, based on a pooled sample of the three replicates. Extensograph properties of the obtained dough were assessed according to ICC standard method 114/1; area under curve (energy, cm2), resistance to extension at 5 cm extension (EE), and extensibility of the dough (mm) were measured. The analyses were performed by the accredited laboratory “Versuchsanstalt für Getreideverarbeitung” based in Austria (<a href="https://www.vfg.or.at/">https://www.vfg.or.at/</a>).   Nutritional characteristics  </div> <div> </div> <div>We assessed the structure of starch (amylose content) and the fatty acid composition for each variety in Changins. These analyses were done by pooling grains from the three replicates in Changins and milling them. The amylose and amylopectin contents of starch were determined enzymatically via an assay based on the precipitation of amylopectin complexes with the lectin concanavalin A, according to K-Amy 06/18. The fatty acid composition was analyzed by GC-FAME, via in situ transesterification, according to the method of Ampuero Kragten et al. (<a title="Kragten SA, Collomb M, Dubois S, Stoll P (2014) Determination of fatty acid composition in feed: analytical methods. Agrarforschung Schweiz 5(9):330&ndash;337" href="https://link.springer.com/article/10.1007/s10681-024-03400-8#ref-CR36">2014</a>). These analyses were performed at the accredited analytical laboratory of Agroscope, Posieux.</div> <div> </div> <div>Kragten SA, Collomb M, Dubois S, Stoll P (2014) Determination of fatty acid composition in feed: analytical methods. Agrarforschung Schweiz 5(9):330–337</div> <div> </div> <div> </div> <div>DNA extraction & Genotyping </div> <div> </div> <div>DNA was extracted from all cultivars, and sent to TraitGenetics (SGS institute Frenius, Gatersleben DE) for SNP genotyping on the 25 K XT Infinium array for wheat.</div> <div> </div> <div> </div>

Data for: Brood parasitism of Hooded Warblers by Brown-headed Cowbirds: Severe impact on individual nests but modest consequences for seasonal fecundity and conservation

<div> <div> <div> <div> Brood parasitism by Brown-headed Cowbirds (Molothrus ater) often has pronounced negative effects on host nests. However, the extent to which parasitism reduces annual reproduction and presents conservation challenges for host species is unclear. We address this issue with data from a color-banded population of Hooded Warblers (Setophaga citrina) in Pennsylvania, where Hooded Warblers have increased dramatically despite frequent nest parasitism. Our analysis is based on both an extensive dataset (8 years, 847 nests) on the per-nest impacts of cowbird parasitism, and female-based stochastic simulations that accurately reflect the reproductive biology and parasitism rate (30%) of our study population. Cowbird parasitism has multiple negative consequences for Hooded Warbler nests, including: (1) reduced host clutch size, (2) increased nest abandonment, (3) increased risk of complete failure due to predation, and (4) in surviving nests increased egg loss, hatching failure, and nestling mortality. We estimate that parasitism reduces success of Hooded Warbler nests 68%, from 1.29 to 0.41 fledglings per nest. For females and populations, however, the consequences of nest parasitism are considerably less extreme; female annual fecundity decreases 25% for each nesting attempt parasitized, and population-level fecundity drops 5.6% for each 10% increase in the frequency of parasitism. These more modest impacts are attributable to: (1) steep declines in rates of cowbird parasitism as the nesting season progresses, (2) rapid re-nesting following abandonment or failure of parasitized nests, and (3) regular double brooding, with second broods initiated in late June and July when the incidence of cowbird parasitism is low. Our results help resolve the paradox of how cowbird parasitism can have both severe consequences for individual host nests but more modest and sustainable conservation impacts on the seasonal fecundity of females and populations. They further underscore the importance of determining population-level effects of brood parasites before investing in costly management efforts. </div> </div> </div> </div>

Resources and seasonality drive the composition of mixed-species bird flocks along an elevational gradient in the Himalaya

Mixed-species bird flocks are cohesive networks of interacting insectivorous bird species that benefit from reduced predation risk and/or enhanced resource access. We studied how species' propensity to participate in mixed flocks, and the number and strength of interspecific associations within flocks, changed along elevational (low, mid, high) and seasonal (winter, spring) gradients in the western Himalaya. We expected species to have high propensities, and greater number and strength of interspecific associations when resources are scarce, and to decline when resources are abundant. We first used species occurrence within and outside mixed flocks to calculate species-specific flocking propensity and then performed network analyses to quantify the proportion of realized interspecific associations (network density) and their strength (weighted degree), using an abundance-based null model to control flocking species' availability. Further, we quantified arthropod prey availability in winter by using a branch bagging technique. Insect availability and arthropod diversity decreased with increasing elevation in winter and species' flocking propensities, network densities and weighted degrees increased with elevation, possibly to benefit from facilitative interactions that increase foraging success. In spring, as more resources become available and/or bird start investing more time in breeding, flocking propensities, network densities and species' weighted degrees declined at all elevations when compared with winter. During resource-scarce periods, species might find solitary foraging prohibitive because of reduced resource access and costs of vigilance therefore leading to the formation of networks of facilitative associations.

opencc-by-4.0Feb 2022View details →

Seasonal and geographic variations of marine litter: a comprehensive study from the island of Cyprus - The Dataset

This dataset includes marine litter data collected from 20 beaches around the island of Cyprus, in the Mediterranean. The beaches were monitored over four monitoring sessions, from January to September 2021, to assess marine litter amounts, categories and spatiotemporal distribution.

Rapid and transient evolution of local adaptation to seasonal host fruits in an invasive pest fly

Both local adaptation and adaptive phenotypic plasticity can influence the match between phenotypic traits and local environmental conditions. Theory predicts that environments stable for multiple generations promote local adaptation, while highly heterogeneous environments favor adaptive phenotypic plasticity. However, when environments have periods of stability mixed with heterogeneity, the relative importance of local adaptation and adaptive phenotypic plasticity is unclear. Here, we used Drosophila suzukii as a model system to evaluate the relative influence of genetic and plastic effects on the match of populations to environments with periods of stability from three to four generations. This invasive pest insect can develop within different fruits, and persists throughout the year in a given location on a succession of distinct host fruits, each one being available for only a few generations. Using reciprocal common environment experiments of natural D. suzukii populations collected from cherry, strawberry and blackberry, we found that both oviposition preference and offspring performance were higher on medium made with the fruit from which the population originated, than on media made with alternative fruits. This pattern, which remained after two generations in the laboratory, was analyzed using a statistical method we developed to quantify the contributions of local adaptation and adaptive plasticity in determining fitness. Altogether, we found that genetic effects (local adaptation) dominate over plastic effects (adaptive phenotypic plasticity). Our study demonstrates that spatially and temporally variable selection does not prevent the rapid evolution of local adaptation in natural populations. The speed and strength of adaptation may be facilitated by several mechanisms including a large effective population size and strong selective pressures imposed by host plants.

Tradeoffs and benefits explain scaling, sex differences, and seasonal oscillations in the remarkable weapons of snapping shrimp (Alpheus spp.)

Evolutionary theory suggests that individuals should express costly traits at a magnitude that optimizes the cost-benefit ratio for the trait-bearer. Trait expression varies across a species because costs and benefits vary among individuals. For example, if large individuals pay lower costs than small individuals, then larger individuals should reach optimal cost-benefit ratios at a greater magnitude of trait expression. Using the remarkable cavitation-shooting weapons found in the big claws of male and female alpheid snapping shrimp, we test whether size- and sex-dependent expenditures explain the scaling of weapon size relative to body size and why males have larger proportional weapon size than females. We found that males and females from three snapping shrimp species (Alpheus heterochaelis, Alpheus angulosus, and Alpheus estuariensis) exhibit resource allocation tradeoffs between weapon and abdomen mass. For male A. heterochaelis, the species for which we had the greatest sample size and statistical power, the smallest individuals showed the steepest tradeoff. Our extensive dataset in A. heterochaelis also included data about pairing, breeding season, and egg clutch size. Therefore, we could test for reproductive tradeoffs and benefits in this species. Female A. heterochaelis exhibited additional tradeoffs between weapon size and egg count, average egg volume, and total egg mass volume. For average egg volume, the smallest females exhibited the steepest tradeoff relative to weapon size. Furthermore, for both sexes, large weapons were positively correlated with the relative size of their pair mate; however, for males only, large weapons were positively correlated with being paired in the first place. In conclusion, we establish that size-dependent tradeoffs underlie reliable scaling relationships of costly traits. Furthermore, we show that males and females differ in weapon investment, suggesting that weapons are especially beneficial to males and especially burdensome to females.

Data for: Wild microbiomes of striped plateau lizards vary with sex, body size, and reproductive season

Long-term natural studies are valuable for examining the effects of host demographics and environmental factors on animal microbiomes, and how those effects interact and shift over time. We examined how the cloacal microbiome of Sceloporus virgatus (the striped plateau lizard) varies under natural conditions in southeastern Arizona, USA, in a multi-year study. Cloacal swabs were collected from wild-caught lizards across their entire active season over three years. Analyses of 16S rRNA data generated on the Illumina platform revealed cloacal microbiomes of S. virgatus vary as a function of sex, season, size, and reproductive state, and do so independently of one another. Briefly, microbial diversity was higher in females than in males, increased with body size, was lowest in both sexes during the reproductive season, and was lowest in females when they were vitellogenic. It was not significantly affected by hibernation. This study highlights the importance of long term, wide scale microbiome studies for capturing accurate perspectives on microbiome diversity and composition in a given species. It also serves as a warning for comparisons of microbiomes across species, as each may be under a different suite of selective pressures from external or innate factors, which may differ in a species-specific manner.

Data for: Similar environmental cues guide timing of breeding and seasonal shifts in songbird social structure

Seasonally breeding animals often exhibit different social structures during non-breeding and breeding periods that coincide with seasonal environmental variation. Therefore, ongoing climate change may play an important role in determining the future structure of animal societies, especially if climate determines when seasonal shifts in social structure occur. However, we know little about the environmental cues that determine the timing of seasonal shifts in social structure, a lack of knowledge that contrasts with our well-defined knowledge of the environmental cues that trigger a shift to breeding physiology in seasonally breeding species. Here we tested whether the environmental cues that drive seasonal shifts in social structure are similar to those that determine timing of breeding in the red-backed fairywren (Malurus melanocephalus), an Australian songbird. Social network analyses revealed that social groups, which are highly territorial during the breeding season, interact in social "communities" on larger ranges during the non-breeding season. Interactions among non-breeding groups were related to rainfall, with more rainfall leading to reductions in home range size and fewer interactions among non-breeding social groups. Similarly, onset of breeding was also determined by rainfall during the non-breeding season, with greater rainfall leading to earlier breeding. These findings reveal that for some species, the cues that determine the timing of shifts in social structure across seasonal boundaries can be similar to those that determine timing of breeding. This study increases our understanding of how social structure and the selection pressures that result from different social structures might respond to changing climates.

opencc-by-4.0Dec 2022View details →

Sharpening of Cold Season Storms over the Western US: companion dataset

This folder includes the intermediate data and scripts (of plots in the main text) for the following manuscript: Chen et al., Sharpening of Cold Season Storms over the Western US. The simulations are done using WRF V3.8 at PNNL. A historical simulation ("NARR") is done for 1981-2010, and five future simulations ("CanESM2", "CESM1-CAM5", "GFDL-ESM2M", "HadGEM2-ES", "MPI-ESM-MR") are done for 2041-2070 using the Pseudo Global Warming (PGW) approach. For the WRF model configuration and the simulation details, please refer to the abovementioned manuscript and Chen et al. (2018). The precipitation objects are then identified using the 5 mm/day threshold. The paths in the scripts are self-consistent. You can just download the .zip file and run the Jupyter notebook to reproduce the figures in the paper.   Reference: Chen, X., L. R. Ruby, Y. Gao, Y. Liu, M. Wigmosta, and M. Richmond (2018), Predictability of Extreme Precipitation in Western U.S. Watersheds Based on Atmospheric River Occurrence, Intensity, and Duration, Geophys. Res. Lett. doi: <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079831">10.1029/2018GL079831</a> Chen, X., L. R. Ruby, Y. Gao, Y. Liu, and M. Wigmosta (2023), Sharpening of cold-season storms over the western United States, Nat. Clim. Change. doi: <a href="https://www.nature.com/articles/s41558-022-01578-0">10.1038/s41558-022-01578-0</a>

opencc-by-4.0Dec 2022View details →

Big Dipper in Four Seasons

Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   As Earth moves around the Sun, the positions of the stars in the night sky appear to change over the course of the year. This is well exemplified in this mosaic, with images taken in all four seasons throughout 2020 in the region of Veneto, Italy, showing the apparent motion of the Ursa Minor and Ursa Major constellations. Ursa Minor, the Little Bear, is a constellation of the northern hemisphere, and it contains the northern celestial pole, in our current epoch marked by a bright star called Polaris or the Pole Star. For centuries Polaris has been used for navigation in the northern hemisphere, as it has been almost at the exact pole position for roughly 200 years. In the Middle Ages and antiquity, there was no pole star; the celestial north pole lay in a dark region and the Greeks considered the “Little She-Bear” as a companion of the “Great She-Bear”, which is more easily recognizable. The brightest stars of these constellations were alternatively also considered as chariots by the Greeks, as written in Aratus’s famous didactic poem from the 3rd century before the common era. The most famous asterism in Ursa Major, composed of seven stars, has different names across the (northern) world. While considered as a chariot by the Greeks, it is “The Northern Dipper” in China, and “The Seven Oxen” for the ancient Romans. It was also the navigational purpose that led to the name The Great She-Bear, Ursa Major; for the Greeks, travelling towards the direction of the horizon above which Ursa Major appears meant moving towards the land of the bears (northern Europe). An animal is clearly recognizable when taking into account all the fainter stars in the vicinity of the seven bright ones. They considered it a female bear because Greek mythology connects this animal with the nymph Callisto, whose story describes the initiation rituals for women. In the top left, we see an image taken on a spring evening, while the image below shows the same portion of the sky on a summer evening. Going counterclockwise, we see the sky during autumn in the bottom right image, while the top right finally shows this portion of the sky in the winter. Note that the relative positions of Ursa Minor and the Big Dipper don’t change, but all stars appear to be moved in a circle around Polaris. This star pointing due north lies at the point where Earth’s rotational axis intersects the celestial sphere. The shift of constellations throughout the year is therefore a globe-clock or a globe-calendar, used by ancient civilizations to measure the year, and to predict the changes of seasons. It helps to establish, for instance, the best time for sowing and sailing as winds change with the seasons. Credit: Giorgia Hofer/IAU OAE (<a href="https://creativecommons.org/licenses/by/4.0/legalcode">CC BY 4.0</a>)

opencc-zeroDec 2022View details →

Extremely low seasonal prey capture efficiency in a deep-diving whale, the narwhal

Successful foraging is essential for individuals to maintain the positive energy balance required for survival and reproduction. Yet, prey capture efficiency is poorly documented in marine apex predators, especially deep-diving mammals. We deployed acoustic tags and stomach temperature pills in summer to collect concurrent information on presumed foraging activity (through buzz detection) and successful prey captures (through drops in stomach temperature), providing estimates of feeding efficiency in narwhals. Compared to the daily number of buzzes (706.9 ± 368), the daily rate of feeding events was particularly low in summer (19.8 ± 8.9), and only 8–14% of the foraging dives were successful (i.e., with a detectable prey capture). This extremely low success rate resulted in a very low daily food consumption rate (< 0.5% of body mass), suggesting that narwhals rely on body reserves accumulated in winter to sustain year-round activities. The expected changes or disappearance of their wintering habitats in response to climate change may therefore have severe fitness consequences for narwhal populations.

opencc-zeroJan 2023View details →

Leaf gene expression trajectories during the growing season are consistent between sites and years in American beech

Transcriptomics, the quantification of gene expression, provides a versatile tool for ecological monitoring. Here, we show that through genome-guided profiling of transcripts mapping to 33,042 loci, gene expression differences can be discerned among multi-year and seasonal leaf samples collected from American beech trees at two latitudinally separated sites. Despite a bottleneck imposed due to large-scale post-Columbian deforestation, the SNP-based population genetic background analysis has yielded sufficient variation to account for differences between populations and among individuals. Our time series of expression analyses during spring-summer and summer-fall transitions for two consecutive years involved 4197 differentially expressed protein coding genes. A global comparison of 12 seasons has revealed that spring gene expression sets the pace for the rest of the growing season. Using \textit{Populus} orthologs of the differentially expressed genes, we reconstructed a protein-protein interactome as a representation of the leaf physiological states of trees during the seasonal transitions. Gene set enrichment analysis revealed GO terms that highlight molecular functions and biological processes possibly influenced by abiotic forcings such as recovery from drought and response to excess precipitation. Further, based on 324 co-regulated transcripts, we focused on a subset of terms that could be putatively attributed to phenological shifts due to late spring. Our conservative results indicate that extended transcriptome-based monitoring of forests can capture ranges of responses arising from other factors including air quality, chronic disease as well as herbivore outbreaks that require activation and/or downregulation of genes collectively tuning reaction norms needed for the survival of long living trees such as the American beech.

opencc-zeroJan 2023View details →

Size-associated energetic constraints on the seasonal onset of reproduction in a species with indeterminate growth

The seasonal onset of reproduction is constrained in many systems by a need to first accumulate energetic reserves. Consequently, the observation that larger individuals reproduce earlier may be due to a negative relationship between size and mass-specific basal metabolic rate that is shared across diverse taxa. However, an untested prediction of this hypothesis is that individuals should be metabolically efficient enough to escape energetic constraints above a certain size threshold. Seasonally reproducing species, such as temperate fishes, that must recover winter energy losses before reproduction and exhibit indeterminate growth are ideal models to test this prediction. We harness decade-long behavioral data on parental male smallmouth bass, Micropterus dolomieu, to investigate contributions of energetic allometry to differences in reproductive timing. At the population level, peak seasonal reproductive timing (i.e., the median date on which eggs were found in nests each year) was negatively related to degree days–a measure of thermal energy experienced–before reproduction. At the individual level, degree days accumulated by males before reproduction was related to male size and condition in every year, but the impact of temperature on reproductive timing by the largest males was relaxed in most years. Additionally, we used our data to replicate the analyses of two previous studies of M. dolomieu populations and found virtually identical negative associations between male body size and degree days accumulated before reproduction. Our results suggest that in smallmouth bass the onset of seasonal reproduction is constrained by basal metabolic rate–as indicated by total length–and that large individuals can escape size-associated energetic constraints. We reveal a more complicated relationship between size and reproductive timing than earlier studies, which may be relevant for many species. Knowledge of this relationship is critical to understanding how a changing climate will influence population dynamics of economically, ecologically, and recreationally important species like M. dolomieu.

opencc-zeroFeb 2023View details →

Priority effects determine how dispersal affects biodiversity in seasonal metacommunities

The arrival order of species frequently determines the outcome of their interactions. This phenomenon, called the priority effect, is ubiquitous in nature and determines local community structure, but we know surprisingly little about how it influences biodiversity across different spatial scales. Here, we use a seasonal metacommunity model to show that biodiversity patterns and the homogenizing effect of high dispersal depend on the specific mechanisms underlying priority effects. When priority effects are only driven by positive frequency dependence, dispersal-diversity relationships are sensitive to initial conditions but generally show a hump-shaped relationship: biodiversity declines when dispersal rates become high and allow the dominant competitor to exclude other species across patches. When spatiotemporal variation in phenological differences alters species' interaction strengths (trait-dependent priority effects), local, regional, and temporal diversity are surprisingly insensitive to variation in dispersal, regardless of the initial numeric advantage. Thus, trait-dependent priority effects can strongly reduce the effect of dispersal on biodiversity, preventing the homogenization of metacommunities. Our results suggest an alternative mechanism that maintains local and regional diversity without environmental heterogeneity, highlighting that accounting for the mechanisms underlying priority effects is fundamental to understanding patterns of biodiversity.

opencc-by-4.0Feb 2023View details →

Seasonal and episodic runup variability on a Caribbean reef-lined beach

This dataset contains data extracted from two cross-shore profiles used in the study. The dataset includes the date of observations, daily total water level (dTWL) for each profile, and the elevation of the vegetation limit for profile 1. The file consists of eight columns arranged in the following order: year, month, day, hour, dTWL for profile 1 (in meters), dTWL for profile 2 (in meters), vegetation limit elevation for profile 1 (in meters), and vegetation limit elevation for profile 2 (in meters).

opencc-zeroMar 2023View details →

Data from: Seasonality and growth in tropical freshwater ectotherm vertebrates: results from one-year experimentation in the African grey bichir, giraffe catfish, and the West African mud turtle

Growth in ectotherm vertebrates is strongly rhythmed by seasonal variation in environmental parameters. To track the seasonal variation in ancient times in a continental and tropical context, we aim to develop a method based on the use of the growth rate of fossil ectotherm vertebrates (actinopterygians and chelonians) influenced by seasonal environmental fluctuations they experienced in their lifetime. However, the impact of environmental parameters on growth, positive or negative, and its intensity, depends on the taxa considered and data are scarce for tropical species. For one year, an experiment was conducted to better understand the effect of seasonal variation in environmental parameters (food abundance, temperature, and photoperiod) on the somatic growth rate of three species of tropical freshwater ectotherm vertebrates: the fishes Polypterus senegalus and Auchenoglanis occidentalis and the turtle Pelusios castaneus. Mimicking seasonal shifts expected to be experienced by the animals in the wild, the experiment highlighted the preponderant effect of food abundance on the growth rate of those three species. Water temperature variation had a significant effect on the growth rate of Po. senegalus and Pe. castaneus. Moreover, the photoperiod demonstrated no significant effect on the growth of the three species. The duration of application of starvation or cool water conditions, ranging from 1 to 3 months, did not affect the growth rate of the animals. However, Pe. castaneus showed a temporary sensitivity to the return of ad libitum feeding or of warm water, after a period of starvation or cool water, by a period of compensatory growth. Finally, this experiment revealed, in the three species, fluctuations in the growth rate under controlled and constant conditions. This variation, similar to the variation in precipitation and temperature observed in their native environment, could be linked to a strong effect of an internal rhythm controlling somatic growth rate.

opencc-zeroApr 2023View details →

Various seasonal pattern and mechanisms of soil nitrogen transformation along elevations in the Hengduan Mountains

Soil nitrogen (N) transformation, a key microbial process in global N cycling, is thought to alter soil N availability and subsequently regulate ecosystem functioning. In particular, the gross rates of N transformation can provide a deeper understanding of internal N dynamics and mechanisms, but questions of whether gross N transformation processes and their underlying drivers change with seasons and elevations remain large uncertain. Based on field collection along an elevational gradient and laboratory incubation experiments, we investigated the seasonal processes of soil N mineralization and nitrification with 15N isotope dilution technique, and also explored the potential mechanisms involved in the Hengduan Mountains. Unimodal soil gross/net mineralization rates were higher in the wet season (61.32 mg kg-1 d-1; 1.01 mg kg-1 d-1; respectively) than in the dry season (10.88 mg kg-1 d-1; 0.55 mg kg-1 d-1; respectively) (P < 0.001), with a peak at medium elevation. Soil gross/net nitrification rates were lower in the wet season (1.43 mg kg-1 d-1; -0.017 mg kg-1 d-1) than in the dry season (2.49 mg kg-1 d-1; 0.004 mg kg-1 d-1; respectively) (P < 0.001), which increased with increasing elevation. The results detected the dominant drivers of the gross transformation rates, specifically microbial attributes occupied crucial roles in controlling the gross mineralization/nitrification in the wet season, and soil physicochemical properties were dominant controllers on the gross mineralization/nitrification during the dry season. This study revealed the divergent patterns and drivers of N transformation, suggesting that seasonal N cycling should no longer be overlooked if we are to predict N biogeochemical cycles in response to environmental change accurately.

opencc-zeroNov 2019View details →

FIG. 6 in A small elevational gradient shows negative bottom-to-top bryophyte richness in a seasonally dry forest in Brazil

FIG. 6. — Bryophytes species distributions along an elevational gradient in Catimbau National Park according to life history traits: A, light requirements; B, life-forms. TABLE 3. — Spearman (Rs) correlation table between life history traits showing that light demanding and life-forms are correlated with the species richness in base and top of elevational gradient, respectively. Italic font indicates Spearman value and normal font indicates Spearman coefficient (Rs). P-value in bold are significant (p <0.05).

opencc-zeroNov 2019View details →

FIG. 3 in A small elevational gradient shows negative bottom-to-top bryophyte richness in a seasonally dry forest in Brazil

FIG. 3. — The effects of altitude decomposed into three elevational belts on bryophyte richness. Model based on the Poisson distribution and log connection method for unprocessed data. Own illustration: Fabronia ciliaris (Brid.) Brid.