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Data from: A growth-defense trade-off is general across native and exotic grasses
High-resource environments typically favor quick-growing, poorly-defended plants, while resource-poor environments typically favor slow-growing, well-defended plants. The prevailing hypothesis explaining this pattern states that, as resource availability increases, well-defended, slow-growing species are replaced by poorly defended, fast-growing species. A second hypothesis states that greater resource availability increases allocation to growth at the expense of defense, within species. Regardless of mechanism, if exotic species are released from enemies relative to natives, shifts in allocation to growth and defense both within and among species could differ by geographic provenance. To test whether resource availability alters growth or defense, within and among species, and whether any such effects differ between natives and exotics, we manipulated soil nutrient supply and access of aboveground insect herbivores and fungal pathogens under field conditions to individuals of six native and six exotic grass species that co-occurred in a North Carolina old field. The prevailing hypothesis' prediction—that species-level enemy impact increases with species' nutrient responsiveness—was confirmed. Moreover, this relationship did not differ between native and exotic species. The second hypothesis' prediction—that individual-level enemy impact increases with nutrient supply, after accounting for species-level variation in performance—was not supported. Together, these results support the idea, across native and exotic species, that plant species turnover is the primary mechanism underlying effects of nutrient enrichment on allocation to growth and defense in plant communities.
Figure 1 in The species of Astymachus Howard (Hymenoptera: Encyrtidae)ı potentially important parasitoids of Aclerdidae (Hemiptera: Coccoidea) associated with grasses (Poaceae)ı with descriptions of three new species
Figure 1. Astymachus lasallei habitus ♀ (critical point dried, card-mounted specimen).
Applying RGB- and Thermal-Based Vegetation Indices from UAVs for High-Throughput Field Phenotyping of Drought Tolerance in Forage Grasses
<p>Basic data from publication <a href="https://doi.org/10.3390/rs13010147">https://doi.org/10.3390/rs13010147</a></p> <p><strong>All_TDRdata.csv</strong> contains the data from 48 TDR sensors (30 cm) installed in the three rainout shelters.</p> <ul> <li>Sensors 1 - 18 were installed vertically to obtain soil moisture content averaged over the 10 - 40 cm profile, on 6 locations per shelter</li> <li>Sensors 19-21 were installed diagonally to obtain soil moisture content averaged over the 20 - 40 cm profile on one location per shelter</li> <li>Sensors 22-24 were installed diagonally to obtain soil moisture content averaged over the 40 - 60 cm profile on one location per shelter</li> <li>Sensors 25-27 were installed horizontally to obtain soil moisture content at 10 cm depth on one location per shelter</li> <li>Sensors 28-30 were installed horizontally to obtain soil moisture content at 20 cm depth on one location per shelter</li> <li>Sensors 31-33 were installed horizontally to obtain soil moisture content at 30 cm depth on one location per shelter</li> <li>Sensors 34-36 were installed horizontally to obtain soil moisture content at 40 cm depth on one location per shelter</li> <li>Sensors 37-39 were installed horizontally to obtain soil moisture content at 50 cm depth on one location per shelter</li> <li>Sensors 40-42 were installed horizontally to obtain soil moisture content at 60 cm depth on one location per shelter</li> <li>Sensors 43-45 were installed horizontally to obtain soil moisture content at 70 cm depth on one location per shelter</li> <li>Sensors 46-48 were installed horizontally to obtain soil moisture content at 80 cm depth on one location per shelter</li> </ul> <p>Climate.txt contains the daily averaged microclimatic data</p> <p>PhenotypingData.csv contains the phenotypic data from the UAV flights and the breeder scores</p> <p> </p>
C4 photosynthesis and the economic spectra of leaf and root traits independently influence growth rates in grasses
<p>Photosynthetic pathway is an important cause of growth rate variation between species, such that the enhanced carbon uptake of C<sub>4</sub> species leads to faster growth than their C<sub>3</sub> counterparts. Leaf traits that promote rapid resource acquisition may further enhance the growth capacity of C<sub>4</sub> species. However, how root economic traits interact with leaf traits, and the different growth strategies adopted by plants with C<sub>3</sub> and C<sub>4</sub> photosynthetic pathways is unclear. Plant economic traits could interact with, or act independently of, photosynthetic pathway in influencing growth rate, or C<sub>3</sub> and C<sub>4</sub> species could segregate out along a common growth rate-trait relationship.</p> <p>We measured leaf and root traits on 100+ grass species grown from seeds in a controlled, common environment to compare with relative growth rates (RGR) during the initial phase of rapid growth, controlling for phylogeny and allometric effects.</p> <p>Photosynthetic pathway acts independently to leaf and root functional traits in causing fast growth. Using C<sub>4</sub> photosynthesis, plants can achieve faster growth than their C<sub>3</sub> counterparts (by an average 0.04 g g<sup>-1</sup> day<sup>-1</sup>) for a given suite of functional trait values, with lower investments of leaf and root nitrogen. Leaf and root traits had an additive effect on RGR, with plants achieving fast growth by possessing resource-acquisitive leaf traits (high specific leaf area and low leaf dry matter content) or root traits (high specific root length and area, and low root diameter), but having both leads to an even faster growth rate (by up to 0.06 g g-1 day-1). C<sub>4</sub> photosynthesis can provide a greater relative increase in RGR for plants with a 'slow' ecological strategy than in those with fast growth. However, aboveground and belowground strategies are not coordinated, so that species can have any combination of 'slow' or 'fast' leaf and root traits.</p> <p>Synthesis: C<sub>4</sub> photosynthesis increases growth rate for a given combination of economic traits, and significantly alters plant nitrogen economy in the leaves and roots. However, leaf and root economic traits act independently to further enhance growth. The fast growth of C<sub>4</sub> grasses promotes a competitive advantage under hot, sunny conditions.</p>
Data from: Specimen-based analysis of morphology and the environment in ecologically dominant grasses: the power of the herbarium
Herbaria contain a cumulative sample of the world's flora, assembled by thousands of people over several hundred years. Recent advances in computation, DNA sequencing, and image manipulation have allowed us to capitalize on this resource. Using herbarium material, we conducted a species-level analysis of a major clade in the grass tribe Andropogoneae, which includes the dominant species of the world's grasslands, from the genera Andropogon, Schizachyrium, Hyparrhenia, and other groups. We imaged 188 of the 250 available species of the clade, georeferenced the specimens, and extracted climatic variables for each. Using semiand fully automated image analysis techniques, we extracted spikelet morphological characters and correlated these with environmental variables. We are currently generating chloroplast genome sequences to correct for phylogenetic covariance and here present an analysis of a subset of 81 species, representing the power of this approach. In addition to taxonomic/phylogenetic observations, we find all morphological and ecological characters are homoplasious but variable among clades. For example, sessile spikelet length is positively correlated with awn length when all accessions are considered, but when separated by clade, the relationship is positive for five sub-clades and negative for three others. Macrohair density and pedicel length were negatively correlated with precipitation.
Effects of three-dimensional soil heterogeneity and species composition on plant biomass and biomass allocation of grass-mixtures
<p>Soil heterogeneity significantly affects plant dynamics such as plant growth and biomass. Most studies developed soil heterogeneity in two dimensions, i.e. either horizontally or vertically. However, soil heterogeneity in natural ecosystems varies both horizontally and vertically i.e. in three dimensions. Previous studies on plant biomass and biomass allocation rarely considered the joint effects of soil heterogeneity and species composition. Thus, to investigate such joint effects on plant biomass and biomass allocation, a controlled experiment was conducted, where three levels of soil heterogeneity and seven types of species compositions were applied. Such soil heterogeneity was developed by filling nutrient-rich and nutrient-poor substrates in an alternative pattern in pots with different patch sizes (small, medium or large), and species compositions was achieved by applying three plant species (i.e. Festuca elata, Bromus inermis, Elymus breviaristatus) in all possible combinations (growing either in monoculture or in mixtures). Results showed that patch size significantly impacted plant biomass and biomass allocation, which differed among plant species. Specially, at the pot scale, with increasing patch size, shoot biomass decreased, while root biomass and R: S ratio increased, and total biomass tended to show a unimodal pattern, where the medium patch supported higher total biomass. Moreover, at the substrate scale, more shoot biomass and total biomass were found in nutrient-rich substrate. Furthermore, at the community scale, two of the three target plant species growing in monoculture had more shoot biomass than those growing together with other species. Thus, our results indicate soil heterogeneity significantly affected plant biomass and biomass allocation, which differ among plant species, though more research is needed on the generalization on biomass allocation. We propose that soil heterogeneity should be considered more explicitly in studies with more species in long-term experiments.</p>
Synergistic impacts of co-occurring invasive grasses cause persistent effects in the soil-plant system after selective removal
1. Human influence on the environment is so extensive that virtually all ecosystems on the planet are now affected by biological invasions. And, often, ecosystems are invaded by multiple co-occurring non-native species. Hence, it is important to understand the impacts these invasions are producing on biodiversity and ecosystem processes. 2. Here, we present results of a two-year long field experiment where we tested the effects of co-occurring invasive C4 African grasses in a Cerrado area in central Brazil. We compared plant and arthropod communities, plant biomass, and soil nitrogen dynamics and soil chemical characteristics across five experimental treatments: Urochloa decumbens removal, Melinis minutiflora removal, both U. decumbens, and M. minutiflora removal, U. decumbens and M. minutiflora invaded plots, and uninvaded Cerrado. We hypothesized that selective removal of invasive grasses would have distinct effects on the native ecosystem structure and functioning. We expected that each invasive grass would produce a different type of impact on the native ecosystem and that their impacts would be synergistic when co-occurring. 3. Removal of M. minutiflora doubled native plant diversity and biomass when compared to invaded plots, whereas removal of U. decumbens did not alter these parameters. Cerrado plots had four times more plant species than plots cleared of invasives. Removal of invasive grasses did not affect the species richness or community composition of soil epigeal fauna. Cerrado soils had lower fertility, organic matter content, and pH than invaded soils. The effects were generally higher when both invasive grasses were removed, suggesting impacts were synergistic, but M. minutiflora had greater effects on plants and soils than U. decumbens. Both invasive species produced negative impacts, but a single species was the main driver. We also detected persistent effects of the invasive grass species on the ecosystem after two years of removal. 4. We conclude that invasive species of the same functional group have similar types of effects in native ecosystems, but the magnitude of impact was largely dependent on invasive species biomass and cover. Where multiple invasive species are present, research and management of invaded ecosystems should tackle the interacting effects of co-occurring invaders.
Plant biomass, not plant economics traits, determines responses of soil CO2 efflux to precipitation in the C4 grass Panicum virgatum
<p>1. Plant responses to major environmental drivers like precipitation can influence important aspects of carbon (C) cycling like soil CO<sub>2</sub> efflux (J<sub>CO2</sub>). These responses may be predicted by two independent classes of drivers: plant size—larger plants respire more and produce a larger quantity of labile C, and plant economics—plants possessing more acquisitive plant economics strategies (i.e., high metabolic rate and tissue nutrient content) produce higher-quality tissue that respires rapidly and decomposes quickly.</p> <p>2. At two sites in central Texas, USA with similar climates and differing soil characteristics, we examined the response of eight <i>Panicum virgatum</i> genotypes to three annual precipitation levels defined by the driest, average, and wettest years from each site's precipitation history. We evaluated the individual and joint influence of plant genotypes and precipitation on J<sub>CO2</sub> and traits related to plant economics and plant size. We then used confirmatory path analysis to evaluate whether effects of precipitation on J<sub>CO2</sub> were in part related to effects of precipitation on plant economics traits or size ('mediated' effects).</p> <p>3. These genotypes exhibited variation in plant economics traits and aboveground net primary productivity (ANPP), an aboveground measure of plant size. Increasing precipitation increased J<sub>CO2</sub> and ANPP more than plant economics traits. At both sites, ANPP was the single best predictor of J<sub>CO2</sub>. Moreover, the sites differed in the ways that plant size and plant economics traits combined with precipitation to influence J<sub>CO2</sub>. At the Austin site, the positive effect of precipitation on J<sub>CO2</sub> was mediated primarily by ANPP, offset by a smaller effect of leaf nitrogen content; no direct precipitation effect was detected. At the Temple site, increasing precipitation had positive direct and ANPP-mediated effects on J<sub>CO2</sub>. This suggests that greater water limitation at Austin may strengthen the links between plant size and J<sub>CO2</sub>.</p> <p>4. Synthesis Estimates of C cycling can be improved by accounting for mediation of precipitation effects on J<sub>CO2</sub> by plant economics traits and plant size in resource-limited environments.</p>
Data from: Effects of native bryophytes on exotic grass invasion across an environmental gradient
Understanding the role that native biodiversity plays in controlling exotic species invasion is a critical goal in ecology. In terrestrial plant communities, most research has focused on the effects of native vascular plants on invasion by exotic vascular plants. However, in many ecosystems, native bryophytes and other non-vascular plants are common and can affect the establishment, survival and growth of vascular plants. A more complete picture of how native biodiversity affects exotic plant invasion, demands that more studies measure the effects of native bryophytes on exotic vascular plants. Moreover, there is growing realization that the effects of native species on invaders can range from negative to positive and that a complete picture of interactions between native and exotic plants requires measuring interactions in multiple environments. We used both observational and experimental studies to quantify the effects of native moss on two exotic annual grass species along a 200-m environmental gradient in a coastal dune in northern California. We found the effects of bryophytes to be species-specific and to vary with environmental context. Bryophytes facilitated the survival of one exotic grass species at both ends of the environmental gradient. For the other exotic grass species, bryophytes reduced survival at one end of the environmental gradient and had no effect at the other end. Our findings provide an important test of the effects of native bryophytes on exotic vascular plant invasion, and importantly show that these effects can vary dramatically even across local environmental gradients.
Data from: Contrasting per-gram competitive and soil resource effects in grasses and woody plants
1. Plant species differ in their competitive effects by decreasing resource availability via uptake, but in some cases may increase resource availability via non-uptake pathways. Here we explore differences between grasses and woody plants in their competitive effects, and relate these to differences in resource effects. 2. We grew five species each of grasses and woody plants in monocultures for eight years. In the final two growing seasons, competitive effects were measured by growing transplants in all monocultures and in plots without neighbours. 3. Total competitive effects were significantly greater for woody plants than grasses. In contrast, the competitive effect per gram of grasses was about 17 times greater than that of woody plants. 4. For grasses, soil water and soil available N decreased significantly with increasing biomass. In contrast, for woody plants, soil water and soil available N increased significantly with increasing biomass. The results suggest that the intense per-gram competitive effects in grasses is related to the uptake of soil resources, and that the significantly lower per-gram competitive effects of woody plants may be related to their positive effects on soil resources. 5. Synthesis. The results link differences in competitive effects between grasses and woody plants to differences in the direction of their effects on soil resources. These differences may contribute to the entrainment of negative feedback in grasslands, excluding trees by means of strong competition, and the entrainment of positive feedback beneath woody plants establishing in grasslands, resulting in a state change from grassland to woody vegetation.
Data from: Spatial transitions in tree cover are associated with soil hydrology, but not with grass biomass, fire frequency, or herbivore biomass in Serengeti savannahs
1. Although there is a well-known association between tree cover and soil texture in savannahs, the hydrological drivers of tree cover variation have not been systematically explored, particularly in parallel with factors such as fire, herbivory, and tree-grass interactions. The relationship between hydrological factors and tree cover is important for resolving the relative contribution of bottom-up vs. top-down factors in structuring savannah vegetation. 2. We quantified soil moisture dynamics across eight 1-km transects spanning tree cover gradients from open to woody savannah in Serengeti National Park in Tanzania using soil moisture sensors coupled with dataloggers. We mapped tree cover at two spatial scales through supervised classification of high-resolution satellite imagery. We simultaneously produced water retention curves in open and woody habitats within each transect to compare soil hydrological properties and to convert volumetric water content (θ) from dataloggers to plant-available water over the course of an annual cycle. We also quantified grass biomass at 100 locations per transect, estimated fire frequency from MODIS satellite data, and quantified herbivore occupancy with paired camera traps situated in open and woody habitats within each transect. 3. We found a positive relationship between tree cover and soil moisture drainage rate, and found that open habitats had more negative water potentials than woody habitats for a given value of θ. In contrast, we found no evidence for a consistent relationship between grass biomass or fire frequency and tree cover. We found evidence for higher browser occupancy in woody than open habitats, but no habitat effects on herbivores as a group (browsers plus grazers), suggesting that herbivory is unlikely to be the dominant factor explaining variation in tree cover. 4. Our results suggest that variation in tree cover is partly driven by hydrological (edaphic) factors unrelated to fire, herbivory, tree-grass interactions or mean annual precipitation at these spatial scales in Serengeti. We contrast our findings with previous work attributing tree cover shifts in Serengeti to precipitation gradients.
Phenology-based classification of invasive annual grasses to the species level
<p><span>The ability to detect and map invasive plants to the species level, both at high resolution and over large extents, is essential for their targeted management. Yet development of such remote sensing methodology is challenged by the spectral and structural similarities among many invasive and native plant species. We developed a multi-temporal classification approach that uses unmanned aerial vehicle (UAV) imagery to map two invasive annual grasses to the species level, and to distinguish these from key functional types of native vegetation, based upon differences in plant phenology. For a case study area in the western Great Basin, USA, we intentionally over-sampled with frequent (n=9) UAV flights over the growing season. Using this information we compared the importance of spectral variation at a given point in time (i.e., with and without near-infrared wavelengths), with spectral variation across multiple time periods. We found that differences in species phenology allowed for accurate classification of nine cover types, including the two annual grass species of interest, using just three dates of imagery that captured species-specific differences in the timing of active growth, seed head production, and senescence. Availability of near-infrared imagery proved less important than true-color RGB imagery collected at appropriate time periods. Thus, multi-temporal information provides a substitute for more extensive spectral information obtained from a single point in time. The substitution of temporal for spectral information is particularly well suited to UAV remote sensing, where RGB image collection is inexpensive, and the timing can be flexible. The datasets arising from our multi-temporal classification approach provide high-resolution information for modeling patterns of invasive plant spread, for quantifying plant invasion risk, and for early detection of novel plant invasions when patch sizes are still small. Widespread application and up-scaling of our approach requires 42 advances in our ability to model the variability in phenology that occurs across years and over fine spatial scales, even within a single species.</span></p>
Contrasting effects of indigenous arbuscular mycorrhizal fungi on nitrogen absorption of C3 and C4 grasses: Evidence from microcosm and 15N labeling experiments
<p><strong><em>Background and aims</em></strong></p> <p>Nitrogen (N) captured by arbuscular mycorrhizal (AM) symbiosis is a major pathway in the N uptake of host plants. However, the relative contribution of arbuscular mycorrhizal fungi (AMF) to N uptake in different plant functional types has not been well assessed.</p> <p><strong><em>Methods</em></strong></p> <p>Two dominant plant species in semiarid steppe ecosystems on the Mongolian plateau, i.e. <em>Leymus chinensis </em>(C<sub>3</sub> grass) and <em>Cleistogenes squarrosa</em> (C<sub>4</sub> grass), were selected in this study. We conducted a greenhouse manipulation experiment using novel microcosms combined with <sup>15</sup>N labeling techniques and investigated the effect of indigenous AMF on plant growth and quantified their relative contribution to N uptake under high and low levels of available soil N. </p> <p><strong><em>Results</em></strong></p> <p>Indigenous AMF contribute more to N uptake in C<sub>3</sub> grass than that in C<sub>4</sub> grass, and mycorrhizal partners act as parasites for C<sub>4</sub> plant growth. For <em>L. chinensis</em>, indigenous AM symbiosis suppressed plant growth under low soil N but improved plant growth under high soil N conditions. AMF contributed to <em>c.</em> 23% and 20% of the total plant N uptake under low and high soil N conditions, respectively. For <em>C. squarrosa</em>, indigenous AM symbiosis consistently inhibited plant growth under both low and high soil N conditions, and the percent contributions of AMF to N uptake were only <em>c.</em> 9% and 7%, respectively.</p> <p><strong><em>Conclusions</em></strong></p> <p>Our results demonstrate that indigenous AM symbiosis plays a vital role in N uptake by host plants, even in the absence of a positive growth response. AMF can modify the fitness of C<sub>3</sub> and C<sub>4</sub> grasses and thereby alter plant community composition and ecosystem N cycling, particularly under high N conditions. Our study has important implications for improving global N cycling models in the face of increasing global N deposition.</p>
Fig. 9 in The first record of the Far Eastern grass-carrying wasp Isodontia nigella (F. Smith, 1856) (Hymenoptera: Sphecidae: Sphecinae) from the Crimea
Fig. 9. Dynamics of emergence of Isodontia nigella (F. Smith, 1856) imagines from the
Fig. 8 in The first record of the Far Eastern grass-carrying wasp Isodontia nigella (F. Smith, 1856) (Hymenoptera: Sphecidae: Sphecinae) from the Crimea
Fig. 8. Opened nests of Isodontia nigella (F. Smith, 1856) in reed canes. Scale bar =
Data from: Effects of grass functional diversity on invasion success by exotic grasses in Cerrado grasslands
<ol> <li>Invasive species pose significant challenges to successful restoration efforts worldwide. A strategy to reduce invasions is to establish communities consisting of species with varied ecological strategies. These strategies typically align along the conservative and plant size axes, and more recently, along a belowground collaboration axis. However, we lack understanding of how the diverse ecological strategies of Cerrado grass species, their combinations, and their interactions with soil conditions can mitigate invasions.</li> <li>Here, we investigated how native grass communities composed of species with different ecological strategies affect the invasion success in two soil types of abandoned pastures in the Cerrado. Specifically, we tested the hypothesis that greater above- and belowground functional diversity reduces exotic species invasion. We also evaluated whether the isolated effects of native species on invasion were positive or negative.</li> <li>We installed an experiment with species richness ranging from zero to eight native grass species. In November 2019, we sowed species combinations to create communities composed by species with different ecological strategies. We quantified the aboveground biomass of exotic species as a measure of invasion. To characterize the species' ecological strategies, we measured five functional traits.</li> <li>Functional diversity of maximum height and specific root length (SRL) had the highest predictive power, however, the most parsimonious model included only SRL diversity, which represents the collaboration axis. Native aboveground biomass was also negatively related to exotic species biomass. Furthermore, invasion was greater in less stressful soil conditions but did not interact with diversity. The effect of native species varied from facilitation to competition, with the annual fast-growing native species favouring invasion.</li> <li> <em>Synthesis and applications</em>. Our results show that greater functional diversity of combined above- and belowground traits reduces invasion success, shedding light on an underexplored role of SRL diversity. The competitive and facilitative effects of different native species highlight the need for careful selection of the species to be used in restoration programs. Furthermore, the absence of interaction between diversity and soil types highlights the need for an integrated management of the functional composition and edaphic factors to increase resistance to invasion in these Neotropical grass communities.</li> </ol>
Convergent evolution of desiccation tolerance in grasses
<p>Desiccation tolerance has evolved repeatedly in plants as an adaptation to survive extreme environments. Plants use similar biophysical and cellular mechanisms to survive life without water, but convergence at the molecular, gene, and regulatory levels remains to be tested. Here, we explore the evolutionary mechanisms underlying the recurrent evolution of desiccation tolerance across grasses. We present genomes of three resurrection grasses native Sub-Saharan Africa. We leveraged comparative genomic and transcriptomic approaches to identify patterns of convergence and divergence across these species. <strong></strong>We observed substantial overlap in gene duplication and expression associated with desiccation, and syntenic genes of shared origin are activated across species, indicative of parallel evolution. In other cases, similar metabolic pathways are induced, but using different gene sets, pointing towards phenotypic convergence. Species-specific mechanisms supplement these shared core mechanisms, underlining the complexity and diversity of evolutionary adaptations. Our findings provide insight into the evolutionary processes driving desiccation tolerance and highlight the roles of parallel mutation and complementary pathway adaptation in response to environmental challenges.</p>
Effects of short photoperiod and carbohydrate consumption on sleep, liver steatosis, and the gut microbiome in diurnal grass rats
<p>Seasonal affective disorder (SAD) is a recurrent depression triggered by exposure to short photoperiods, with a subset of patients reporting hypersomnia, increased appetite, and carbohydrate craving. Dysfunction of the microbiota–gut–brain axis is frequently associated with depressive disorders, but its role in SAD is unknown. Nile grass rats (Arvicanthis niloticus) are potentially useful for exploring the pathophysiology of SAD, as they are diurnal and have been found to exhibit anhedonia and affective-like behavior in response to short photoperiods. Further, given grass rats have been found to spontaneously develop metabolic syndrome, they may be particularly susceptible to environmental triggers of metabolic dysbiosis. We conducted a 2x2 factorial design experiment to test the effects of short photoperiod (4h:20h Light:Dark (LD) vs. neutral 12:12 LD), access to a high concentration (8%) sucrose solution, and the interaction between the two, on activity, sleep, liver steatosis, and the gut microbiome of grass rats. We found that animals on short photoperiods showed disrupted activity and sleep patterns but maintained robust diel rhythms and similar subjective day lengths as controls in neutral photoperiods. We found no evidence that photoperiod influenced sucrose consumption. By the end of the experiment, some grass rats were overweight and exhibited signs of non-alcoholic fatty liver disease (NAFLD) with micro- and macro-steatosis. However, neither photoperiod nor access to sucrose solution significantly affected the degree of liver steatosis. The gut microbiome of grass rats varied substantially among individuals, but most variation was attributable to parental effects and the microbiome was unaffected by photoperiod or access to sucrose. Our study indicates short photoperiod leads to disrupted activity and sleep in grass rats but does not impact sucrose consumption or exacerbate metabolic dysbiosis and NAFLD.</p>
Supplementary material from: Alpine extremophytes in evolutionary turmoil: Complex diversification patterns and demographic responses of a Halophilic grass in a Central Asian biodiversity hotspot
<p>Diversification and demographic responses are key processes shaping species evolutionary history. Yet we still lack a full understanding of ecological mechanisms that shape genetic diversity at different spatial scales upon rapid environmental changes. In this study, we examined genetic differentiation in an extremophilic grass <em>Puccinellia pamirica</em> and factors affecting its population dynamics among the occupied hypersaline alpine wetlands on the arid Pamir Plateau in Central Asia. Using genomic data, we found evidence of fine-scale population structure and gene flow among the localities established across the high-elevation plateau as well as fingerprints of historical demographic expansion. We showed that an increase in the effective population size could coincide with the Last Glacial Period, which was followed by the species demographic decline during the Holocene. Geographic distance plays a vital role in shaping the spatial genetic structure of <em>P. pamirica</em> alongside with isolation-by-environment and habitat fragmentation. Our results highlight a complex history of divergence and gene flow in this species-poor alpine region during the Late Quaternary. We demonstrate that regional climate specificity and a shortage of nonclimate data largely impede predictions of future range changes of the alpine extremophile using ecological niche modeling. This study emphasizes the importance of fine-scale environmental heterogeneity for population dynamics and species distribution shifts.</p>
Data from: Will trees or grasses profit from changing rainfall regimes in savannas?
<div> <p>• Increasing rainfall variability is widely expected under future climate change scenar- ios. How will savanna trees and grasses be affected by growing season dry spells and altered seasonality and how tightly coupled are tree-grass phenologies with rainfall?</p> <p>• We measured tree and grass responses to growing season dry spells and dry season rainfall. We also tested if the phenologies of 17 deciduous woody species and the Soil Adjusted Vegetation Index of grasses were related to rainfall between 2019 and 2023.</p> <p>• Tree and grass growth was significantly reduced during growing season dry spells. Tree growth was strongly related to growing season soil water potentials and limited to the wet season. Grasses can rapidly recover after growing season dry spells and grass evapotranspiration was significantly related to soil water potentials in both the wet and dry seasons. Tree leaf flushing commenced before the rainfall onset date with little subsequent leaf flushing. Grasses grew when moisture became available regardless of season.</p> </div> <p>• Our findings suggest that increased dry spell length and frequency in the growing season may slow down tree growth in some savannas, which together with longer growing seasons may allow grasses an advantage over C<sub>3</sub> plants that are advantaged by rising CO<sub>2</sub> levels.</p>
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