Livestock grazing can strongly determine how grasslands function and their role in carbon cycle. However, how ecosystem carbon exchange responds to grazing and the underlying mechanisms remain unclear. We measured ecosystem carbon fluxes to explore the changes in carbon exchange and their driving mechanisms in a 16-year long term experiment with different grazing intensities in a desert steppe grassland. We found that grazing intensity influenced above- and belowground biomass during the peak growing season, primarily by decreasing shrubs and semi-shrubs and perennial forbs. Furthermore, alter patterns of net ecosystem exchange primarily via their negative influence on the biomass of shrub and semi-shrub. In addition, grazing-induced reduction belowground biomass, as well as in total plant nitrogen and soil ammonium nitrogen, can strongly influence ecosystem carbon exchange and soil respiration. When nitrogen is lost from the soil due to grazing, plants reallocate resources belowground to maintain growth and development, thus promoting photosynthesis and respiration. Our study indicates that soil available nitrogen and shrubs and semi-shrubs are important factors in regulating ecosystem carbon exchange under grazing disturbance in the desert steppe, which provide a basis for grazing management.

In root-nodule symbioses (RNS) between nitrogen (N) fixing bacteria and plants, bacterial symbionts cycle between nodule-inhabiting and soil-inhabiting niches that exert differential selection pressures on bacterial traits. Little is known about how the resulting evolutionary tension between host plants and symbiotic bacteria structures naturally occurring bacterial assemblages in soils. We used DNA cloning to examine soil-dwelling assemblages of the actinorhizal symbiont Frankia in sites with long-term stable assemblages in Alnus incana ssp. tenuifolia nodules. We compared: 1) phylogenetic diversity of Frankia in soil vs. nodules, 2) change in Frankia assemblages in soil vs. nodules in response to environmental variation: both across succession, and in response to long-term fertilization with N and phosphorus, and 3) soil assemblages in the presence and absence of host plants. Phylogenetic diversity was much greater in soil-dwelling than nodule-dwelling assemblages, and fell into two large clades not previously observed. Presence of host plants was associated with enhanced representation of genotypes specific to A. tenuifolia, and decreased representation of genotypes specific to a second Alnus species. The relative proportion of symbiotic sequence groups across a primary chronosequence was similar in both soil and nodule assemblages. Contrary to expectations, both N and P enhanced symbiotic genotypes relative to non-symbiotic ones. Our results provide a rare set of field observations against which predictions from theoretical and experimental work in the evolutionary ecology of RNS can be compared.

As DNA sequencing technology continues to rapidly improve, studies investigating the microbial communities of host organisms (i.e., microbiomes) are becoming not only more popular but also more financially accessible. Across many taxa, microbiomes can have important impacts on organismal health and fitness. To evaluate the microbial community composition of a particular microbiome, microbial DNA must be successfully extracted. Fecal samples are often easy to collect and are a good source of gut microbial DNA. Additionally, interest in the avian preen gland microbiome is rapidly growing, due to the importance of preen oil for many aspects of avian life. Microbial DNA extractions from avian fecal and preen oil samples present multiple challenges, however. Here, we describe a modified PrepMan Ultra Sample Preparation Reagent microbial DNA extraction method that is less expensive than other commonly used methodologies and is highly effective for both fecal and preen oil samples collected from a broad range of avian species. We expect our method will facilitate microbial DNA extractions from multiple avian microbiome reservoirs, which have previously proved difficult and expensive. Our method therefore increases the feasibility of future studies of avian host microbiomes.

Eusocial insects, such as ants and termites, are characterized by high levels of coordinated social organization. This is contrasted by solitary insects, which display more limited forms of collective behavior. It has been hypothesized that this gradient in socio-behavioral sophistication is positively correlated with chemical profile complexity, due to a potentially increased demand for diversity in chemical communication mechanisms in insects with higher levels of social complexity. However, this claim has rarely been assessed empirically. Here, we compare different levels of chemical and transcriptomic complexity in selected species of the order Blattodea that represent different levels of social organization, from solitary to eusocial. We primarily focus on cuticular hydrocarbon (CHC) complexity, since it has repeatedly been demonstrated that CHCs are key signaling molecules conveying a wide variety of chemical information in solitary as well as eusocial insect species. We assessed CHC complexity and divergence between our studied species of different social complexity levels as well as the differentiation of their respective repertoires of CHC biosynthesis gene transcripts. Surprisingly, we did not find any consistent pattern of chemical complexity correlating with the degree of social complexity, nor did the overall chemical divergence or transcriptomic repertoire of CHC biosynthesis genes reflect on the levels of social complexity. Our results challenge the assumption that increasing social complexity is generally reflected in more complex chemical profiles and point towards the need for a more cautious and differentiated view on correlating complexity on a chemical, genetic, and social level.

We selected 15 sheep-grazed sand pastures along increasing grazing intensity to study fine scale biomass patterns of main fractions (green biomass, litter) and that of plant species and functional groups (life forms and social behaviour types). We classified them into five grazing intensity levels based on stocking rate, proximity to drinking and resting places, and the number of droppings and other tracks of grazing animals. We formulated three study questions: i) How does increasing intensity of sheep grazing affect the amount of green biomass, species richness and their relationship in sand pastures? ii) How does increasing intensity of sheep grazing affect the biomass of perennial and short-lived graminoids and forbs? iii) How does disturbance value (expressed in the biomass ratio of disturbance tolerant and ruderal species) change along the gradient of grazing intensity? A unimodal relationship between green biomass and species richness was detected. Along the grazing intensity gradient, we found an increasing trend for species richness; significant differences for green biomass (decreasing trend) and litter (decreasing trend), moreover for graminoids (decreasing trend), and short-lived forbs (increasing trend). We found an increasing amount of disturbance tolerant and ruderal species with increasing grazing intensity. We concluded that stocking rate and proximity to drinking and resting places jointly affected vegetation and created an uneven pattern for composition and amount of biomass in all grazing intensity levels. Our findings might be instructive for pastures in densely populated regions which are prone to the encroachment of disturbance-tolerant and ruderal species.

1. Rivers are crucial ecosystems supporting biodiversity and human well-being, yet they face increasing degradation globally. Traditional river biomonitoring methods based on morphological identification of macroinvertebrates present challenges in terms of taxonomic resolution and scalability. 2. This study explores the application of DNA metabarcoding analysis in both bulk and environmental DNA (eDNA) samples for comprehensive assessment of macrozoobenthic biodiversity, detection of invasive and endangered species, and evaluation of river ecological status in northwestern Spain. 3. DNA metabarcoding of homogenised bulk samples and water eDNA revealed a mean of 100 and 87 macrozoobenthos species per sample respectively. However, it was a significantly different specific composition with only 27.3% of the total species shared. It was not possible to identify all the OTUs to species level, only 17.43% and 49.4% of the OTUs generated could be identified to species level In the Bulk and eDNA samples respectively. However, a total of 11 exotic species (2 first records for the Iberian Peninsula and another 3 first records for Asturias region) and 1 endangered species were detected by molecular tools. Molecular methods showed significant correlations with morphological identification for EQR values (Ecological quality ratio) of IBMWP index, yet differences in inferred river ecological status were noted, with bulk samples tending to indicate higher status. 4. Overall, DNA metabarcoding offers a promising approach for river biomonitoring, providing insights into biodiversity, invasive species, and ecological status within a single analysis. Further optimization and intercalibration are needed for its implementation in routine biomonitoring programs, but its scalability and multi-tasking capabilities position it as a valuable tool for integrated monitoring of river ecosystems.

Cedrela odorata is considered the second most invasive tree species of the Galapagos Islands. Although it is listed in CITES Appendix II and there are population losses in mainland Ecuador, in Galapagos it is paradoxically a species of concern due to its invasive potential. Genetic studies can shed light on the invasion history of introduced species causing effects on unique ecosystems like the Galapagos. We analyzed nine microsatellite markers in C. odorata individuals from Galapagos and mainland Ecuador to describe the genetic diversity and population structure of C. odorata in the Galapagos and to explore the origin and invasion history of this species. The genetic diversity found for C. odorata in Galapagos (He = 0.55) was lower than reported in the mainland (He = 0.81), but higher than other invasive insular plant species, which could indicate multiple introductions. Our results suggest that Ecuador’s northern Coastal region is the most likely origin of the Galapagos C. odorata, although further genomic studies are needed to confirm this finding. Moreover, according to our proposed pathway scenarios, C. odorata was first introduced to San Cristobal and/or Santa Cruz from mainland Ecuador. After these initial introductions, C. odorata appears to have arrived to Isabela and Floreana from either San Cristobal or Santa Cruz. Here, we report the first genetic study of C. odorata in the Galapagos and the first attempt to unravel the invasion history of this species. The information obtained in this research could support management and control strategies to lessen the impact that C. odorata has on the islands’ local flora and fauna.

Juvenile growth rate is a critical demographic parameter, as it shortens time to maturity and often dictates how long individuals remain vulnerable to predation. However, developing a mechanistic understanding of the factors determining growth rates can be difficult for wild populations. The gopher tortoise (Gopherus polyphemus) is an ecosystem engineer threatened by habitat loss and deficient management of pinelands in the southeastern United States. We investigated the factors governing immature gopher tortoise growth and explored use of drone-based imagery for habitat assessment by comparing predictive models based on ground-based plant surveys versus drone-derived data. From 2021-2022, we tracked and measured immature tortoises in native sandhill and human-modified, ruderal habitat in south-central Florida. Using quarterly, high-resolution drone imagery, we quantified plant cover types and vegetation indices at each occupied burrow, and measured frequency of occurrence of forage species by hand. Annual growth rates of immature tortoises in ruderal habitat were higher than those in sandhill and were the highest published for this species. Models based on drone-derived data were able to explain similar proportions of variation in growth as ground-collected measures of forage, especially during the late dry season when both types of models were most predictive. Habitat differences in forage nitrogen content were also more pronounced during this season, when dominant ground cover in ruderal habitat (bahiagrass) had much higher nitrogen content than dominant ground cover in sandhill (wiregrass). Despite concerns about potential growth-survival trade-offs, tortoises in ruderal habitat did not exhibit lower apparent survival. Our findings indicate that habitat dominated by nutritious non-native grass can provide a valuable supplement to native sandhill through the mechanism of increased growth rates due to higher forage quality. Finally, our study demonstrates that drone technology may facilitate management by providing less labor-intensive ways to assess habitat quality for this and other imperiled herbivores.

High elevation grasslands provide critical services in agriculture and ecosystem stabilization. However, these ecosystems face elevated risks of disturbance due to predicted soil and climate changes. We experimentally exposed model grassland communities, comprised of three species grown on either local or reference soil, to varied climatic environments along an elevational gradient in the European Alps, measuring the effects on species and community traits. Although species-specific biomass varied across soil and climate, species’ proportional contributions to community-level biomass production remained consistent. Where species experienced low survivorship, species-specific biomass production was maintained through increased production of surviving individuals. Species responded directionally to climatic variation, segregating differentially by plant traits (including height, reproduction, biomass, survival, leaf dry weight, and leaf area) across all sites. Local soil variation drove stochastic trait responses across all species. This soil variability obscured climate-driven responses: we recorded no directional trait responses driven by climate. Our species-based approach contributes to our understanding of grassland community stabilization and suggests that these communities show some stability under climatic variation.

Understanding animal movement and behaviour can aid spatial planning and inform conservation management. However, it is difficult to directly observe behaviours in remote and hostile terrain such as the marine environment. Behaviours can be inferred from telemetry data using hidden Markov models (HMMs), but model predictions are not typically validated due to difficulty obtaining ‘ground truth’ behavioural information. We investigate the accuracy of HMM-inferred behaviours by considering a unique dataset provided by Joint Nature Conservation Committee. The data consist of simultaneous proxy movement tracks of the boat (defined as visual tracks as birds are followed by eye) and seabird behaviour obtained at the same time-frequency by observers on the boat. We use these data to assess whether (i) visual track is a good proxy for true bird locations in relation to HMM-inferred behaviours, and (ii) inferred behaviours from HMMs fitted to visual tracking data accurately represent true behaviours as identified by behavioural observations taken from the boat. We demonstrate that visual tracking data can be regarded as a good proxy for true movement data of birds in terms of similarity in inferred behaviours. Accuracy of HMMs ranging from 71% to 87% during chick-rearing and 54% to 70% during incubation was generally insensitive to model choice, even when AIC values varied substantially across different models. Finally, we show that for foraging, a state of primary interest for conservation purposes, identified missed foraging bouts lasted for only a few seconds. We conclude that HMMs fitted to tracking data can accurately identify important conservation-relevant behaviours, demonstrated using visual tracking data. Therefore, confidence in using HMMs for behavioural inference should increase even when validation data are unavailable. This has important implications for animal conservation, where the size and location of protected areas are often informed by behaviours identified using HMMs fitted to movement data.

Global climate change has led to a shift in rainfall patterns. And as water is an essential ingredient for plant photosynthesis, shifts in rainfall patterns will inevitably affect plant growth. In this study, the response of leaf traits and photosynthetic fluorescence properties of Fraxinus malacophylla seedlings to rainfall patterns during the dry and rainy seasons was investigated using a natural rainfall duration of 5 d (T) and an extended rainfall duration of 10 d (T+) as rainfall intervals; and a monthly average rainfall as control (W), with the corresponding rainfall treatments of a 40% increase in rainfall (W+) and a 40% decrease in rainfall (W-). The results showed that Pn, Gs, and Tr basically all tended to increase and then decrease with increasing rainfall in the dry season, and generally reached the highest under the W treatment; and Pn, Gs, Ci, and Tr mostly remained high at 5d relative to 10d; PI was overall higher under the W treatment throughout the dry season. Extending the rainfall interval at the beginning of the rainy season significantly reduced Fm; throughout the rainy season, Gs, Ci, and Tr basically showed a decreasing trend with increasing rainfall, reaching the highest under the W-treatment, and mostly higher at 5d than at 10d. These results suggest that natural rainfall intervals and natural rainfall amounts are more favorable to the growth of Fraxinus malacophylla seedlings in the dry season; reduced rainfall and multiple rainfalls in the rainy season tend to promote photosynthesis in Fraxinus malacophylla. This study reflects the different survival strategies of Fraxinus malacophylla under different rainfall patterns, as well as providing a theoretical basis for understanding how Fraxinus malacophylla can grow better under rainfall variability and for future management.

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

Past forest use often has a long-term negative impact on the recovery of the original plant composition of semi-natural grasslands, which are known as a legacy effect. This study investigates the impact of seed dispersal limitations on the restoration of grassland plant diversity on ski slopes with past forest use, highlighting the negative legacy effect on biodiversity recovery. Focusing on ski areas, our research contrasts the vegetation on ski slopes originally created on semi-natural grasslands such as pasture (pasture slopes) and constructed by clearing secondary forests or conifer plantations (forest slopes). We examined species richness and abundance, considering seed dispersal mechanisms, grassland management history and seed source proximity. We reveal that the proximity to species-rich grassland sources and sustained management for more than 50 years are pivotal for the restoration of native grassland vegetation. Particularly, wind-dispersed species show significant recovery on slopes with a history of extensive grassland management, suggesting that both the duration of management and the proximity to seed sources are critical for overcoming the legacy effects of past forest use. Our findings emphasize the importance of considering seed dispersal dynamics and management history in the restoration and conservation of grasslands and their biodiversity, particularly in landscapes experiencing past human intervention.

Aim: This study aims to enhance our understanding of the temporal and spatial proceses scales governing the taxonomic diversification of Neotropical birds with Trans- and Cis-Andean populations. Location: Central America and South America. Taxon: Attila spadiceus (Bright-rumped Attila). Methods: Through a multilocus analysis of the mitochondrial (CytB and ND2) and nuclear genes (I7BF, I5BF, and G3PDH) of 41 samples representing six subspecies, we describe the existing molecular lineages of A. spadiceus, and estimate their demographic dynamics. We also modeled the climatic niche of the species. Results: The analysis confirms a relatively recent divergence of the Trans- and Cis-Andean lineages, at approximately 0.25 million years ago (Ma). The niche modeling supports the existence of a dynamic scenario of the expansion and retraction of forest corridors in northwestern South America during the last glaciation. This suggests that the earlier orogenesis of the Andes was not a primary determinant of this dichotomy. Additionally, the analysis of population dynamics indicated a trend of increasing population size starting at 0.05 Ma for both lineages. Main Conclusions: Our findings highlight the significance of Pleistocene Forest corridors north of the Andes as the key factor maintaining communication before the separation of the lineages, likely associated with the retraction of this forest. We highlight the absence of any significant differentiation between the disjunct Amazonian and Atlantic Forest populations, both part of the Cis-Andean lineage. The phylogeographic profile of A. spadiceus diverges from the patterns observed in other Neotropical birds, which emphasizes the need for further research on the role of the forest corridors of the northern Andes as drivers of diversification, to provide comprehensive insights into the processes that led to the formation of the region’s present-day avian diversity.

To conserve wide-ranging species in human-modified landscapes, it is essential to understand how the behavior of animals changes in relation to the degree and composition of modification. Evidence suggests that large inter-individual variation exists in the propensity for use of human-modified areas and may be driven by both behavioral and landscape factors. The use of agriculture lands by wildlife is of particular interest, given the importance of reducing human-wildlife conflicts and understanding how such areas can function as biodiversity buffers. African elephant space use can be highly influenced by human activity and the degree to which individuals crop-raid. We analyzed GPS data from 56 free-ranging elephants in the Serengeti-Mara Ecosystem using resource selection functions (RSFs) to assess how crop use may drive patterns of resource selection and space use within a population. We quantified drivers of similarity in resource selection across individuals using proximity analysis of individual RSF coefficients derived from random forest models. We found wide variation in RSF coefficient values between individuals indicating strongly differentiated resource selection strategies. Proximity assessment indicated the degree of crop use in the dry season, individual repeatability, and time spent in unprotected areas drove similarity in resource selection patterns. Crop selection was also spatially structured in relation to agricultural fragmentation. In areas with high fragmentation, elephants spent more time in crops and selected most strongly for crops in areas close to the protected area boundary, but in areas with low fragmentation elephants spent half as much time in crops and selected most strongly for crops further from protected area boundaries. Our results highlight how individual differences and landscape structure can both shape use of agricultural landscapes. We discuss our results in respect to the conservation challenges of human-elephant conflict and incorporating behavioral variation into human-wildlife coexistence efforts.

Abstract: This study explores the habitat distribution of Pterocarpus santalinus, a valuable rosewood species, across China, focusing on its response to current and future climate changes. Utilizing the MaxEnt model, we assess its suitable habitat under present conditions and future climate scenarios (SSPs126, SSPs245, and SSPs585). Our findings reveal that the current suitable habitat, spanning approximately 409,600 km², is primarily located in the central and southern parts of Guangdong, Guangxi, Fujian, Yunnan, as well as in the Hainan provinces, along with the coastal regions of Taiwan, and the Sichuan-Chongqing border. The habitat’s distribution is significantly influenced by climatic factors such as temperature seasonality (bio4), mean temperature of the wettest quarter (bio8), annual mean temperature (bio1), and annual precipitation (bio12), while terrain and soil factors play a lesser role. Under future climate scenarios, the suitable habitat for P. santalinus is projected to expand, with a northeastward shift in its distribution center. This research not only sheds light on the geoecological characteristics and geographical distribution of P. santalinus in China but also offers a scientific basis for planning its cultivation areas and enhancing cultivation efficiency under changing climate conditions.

The study and importance of altitudinal migration has attracted increasing interest among zoologists. Altitudinal migrants are taxonomically widespread and move across environmental gradients that transect altitudinal and latitudinal gradients as partial or complete migrants, subjecting them to a wide array of environments and ecological interactions. Here, we present a brief synthesis of recent development and suggest future directions towards a more taxonomically inclusive conceptual framework for the study of altitudinal migration. Our framework centers on a working definition of altitudinal migration that highlights the biological relevance and scale of movement for a given taxon and its life history. Even with a revised definition, however, the distinction between the narrower phenomenon of migration and wider study of movement often blurs. We discuss nuances of altitudinal movements and encourage comparisons among taxa from divergent lineages and biomes that encounter different ecological interactions and physiological challenges across their annual cycles. We also summarize new opportunities, methods, and challenges for the ongoing study of altitudinal migration. A persistent, primary challenge is characterizing the taxonomic extent of altitudinal migration within and among species. Fortunately, a host of new methods have been developed to help researchers assess the taxonomic prevalence of altitudinal migration---each with their own advantages and disadvantages. An improved conceptual framework of altitudinal migration will allow researchers that study disparate disciplines and taxonomic groups to better communicate and operate in a comparative framework to test hypotheses regarding the evolutionary and ecological drivers underlying variation in altitudinal migration among populations and species.

Quantifying genetic structure and levels of genetic variation are fundamentally important to predicting the ability of populations to persist in human-altered landscapes and adapt to future environmental changes. Genetic structure reflects the dispersal of individuals over generations, which can be mediated by species-level traits or environmental factors. Dispersal distances are commonly positively associated with body size and negatively associated with the amount of degraded habitat between sites, motivating investigation of these potential drivers of dispersal concomitantly. We quantified genetic structure and genetic variability within populations of seven Euglossine bee species in the genus Euglossa across fragmented landscapes. We genotyped bees at thousands of SNP loci and tested the following predictions: (1) deforested areas restrict gene flow; (2) larger species have lower genetic structure; (3) species with greater resource specialization have higher genetic structure; and (4) sites surrounded by more intact habitat have higher genetic diversity. Contrasting with previous work on bees, we found no associations of body size and genetic structure. Genetic structure was higher for species with greater resource specialization, and the amount of intact habitat between or surrounding sites was positively associated with parameters reflecting gene flow and genetic diversity. These results challenge the dominant paradigm that individuals of larger species disperse farther. They suggest that landscape and resource requirements are important factors mediating dispersal, and they motivate further work into ecological drivers of gene flow for bees.