Niche Differences Research Articles

Records of urban occurrences expand estimates of the climate niches in tree species

AbstractAimQuantifying a species' climate niche is often the first step to determining potential sensitivity to climate change. This process typically relies on native occurrence records, assuming that these reflect the breadth of a species' climatic requirements. Yet, many species survive in non‐native regions with climates beyond their native range. Identifying their characteristics could help to better elucidate responses to climate change. Here, we use an extensive data set of urban street tree and native range records for 566 tree species to assess differences between species native and urban climate niches and whether niche differences are predictable given characteristics of species native ranges.LocationGlobal.Time Period1970–2020.Major Taxa StudiedTree species.MethodsMultivariate niche estimations were undertaken using eight climate variables. Calculations included the size of species' urban and native niches, overlap and direction of shift. Relationships between niches and native range attributes (temperature and precipitation breadth, range size, Köppen Geiger subclasses occupied) were calculated using multiple linear regression.Results83% of tree species studied had significantly larger urban niches compared to native niches. Species with narrow geographic ranges demonstrated greater mismatch between their two niches, and the direction of niche shift was associated with their native range Köppen Geiger zone. For example, species native to the wet tropics tend to be planted in cooler, drier urban spaces; those native to cold regions are planted in warmer urban spaces.Main ConclusionNative range occurrences may poorly reflect the breadth of climatic conditions a species can tolerate—particularly for species with narrow geographic ranges. For some species, Köppen Geiger zones may be a useful proxy to help understand sensitivity to climate change. Accounting for possible plasticity in tree species to climate can improve our understanding of their sensitivity and adaptive capacity to climate change.

Habitat selection and refuge-use by a color polymorphic salamander reveal behavioral niche differences.

Color polymorphic species provide an excellent opportunity to investigate the ecology and evolution of intraspecific niche differences. The red-backed salamander, Plethodon cinereus, is a fully terrestrial lungless salamander with two common color forms, striped and unstriped. Previous research suggests the morphs may be differentially adapted to surface and subsurface microhabitats, with the unstriped morph being more fossorial. This hypothesis predicts that the unstriped morph should be more sensitive to the risks of surface activity (e.g., thermal stress, dehydration, predation), and therefore be more selective than striped morphs when choosing soil surface microhabitats. To test this hypothesis, we experimentally manipulated leaf litter mass in small forest patches (~0.45 m2). Leaf litter addition reduced soil temperatures, buffered against changes in air temperature, and likely provided physical protection from predators. Over 3 years, we found that unstriped adults responded positively to leaf litter addition, but striped adults did not. In addition, unstriped morphs spent significantly more time in protective refuges (opaque, moistened tubes) than striped morphs in laboratory assays. Taken together, the field and laboratory results support the hypothesis that the unstriped morph is more sensitive to the risks of surface activity, and therefore is more likely to be fossorial. This difference in microhabitat use, combined with spatiotemporal variation in leaf litter accumulation on the forest floor, may play an important role in the maintenance of the polymorphism.

Differences in spatial niche of terrestrial mammals when facing extreme snowfall: the case in east Asian forests

BackgroundRecent climate changes have produced extreme climate events. This study focused on extreme snowfall and intended to discuss the vulnerability of temperate mammals against it through interspecies comparisons of spatial niches in northern Japan. We constructed niche models for seven non-hibernating species through wide-scaled snow tracking on skis, whose total survey length was 1144 km.ResultsWe detected a low correlation (rs < 0.4) between most pairs of species niches, indicating that most species possessed different overwintering tactics. A morphological advantage in locomotion cost on snow did not always expand niche breadth. In contrast, a spatial niche could respond to (1) drastic landscape change by a diminishing understory due to snow, possibly leading to changes in predator-prey interactions, and (2) the mass of cold air, affecting thermoregulatory cost and food accessibility. When extraordinary snowfall occurred, the nonarboreal species with larger body sizes could niche shift, whereas the smaller-sized or semi-arboreal mammals did not. In addition, compared to omnivores, herbivores were prone to severe restriction of niche breadth due to a reduction in food accessibility under extreme climates.ConclusionsDietary habits and body size could determine the redundancy of niche width, which may govern robustness/vulnerability to extreme snowfall events.

Expression Profiles of Protease in Onychomycosis-Related Pathogenic Trichophyton rubrum and Tinea Capitis-Related Pathogenic Trichophyton violaceum.

The two fungal species Trichophyton rubrum and Trichophyton violaceum are common pathogens on human, infecting keratinized tissue of the outer body parts. Both species are belonging to the "Trichophyton rubrum complex" and share very high similarity in the genome. Secreted proteinases, key factors for keratin degradation, are nearly identical. Contrary, the ecological niches are differing. Trichophyton rubrum preferably infects skin and nails, whereas T. violaceum preferably infects the scalp. We postulate, that differences in the protease expression contribute to differences in ecological preferences. We analyzed the expression profiles of all 22 endoprotease genes, 12 subtilisins (S8A), 5 deuterolysins (M35) and 5 fungalysins (M36), for both species. To compare the influence of the keratin source, we designed experiments with human nail keratin, sheep wool keratin and keratin free cultivation media. Samples were taken at 12h, 24h, 48h and 96h post incubation in keratin medium. The expression of the proteases is higher in wool-keratin medium compared to human nail medium, with the exception of MEP4 and SUB6. Expression in the keratin-free medium is lowest. The expression profiles of the two species are remarkable different. The expression of MEP1, MEP3, SUB5, SUB11 and SUB12 are higher in T. rubrum compared to T. violaceum. MEP2, NpIIc, NpIIe, SUB1, SUB3, SUB4, SUB7 and SUB8 are higher expressed in T. violaceum compared to T. rubrum. The differences of the protease expression in the two species may expalin the differences in the ecological niches. Further analysis are necessary to verify the hypothesis.Please check and conform the edit made in title.Here I thinke the species of strains shouldnt be capital， and the right expression should be, "Expression Profiles of Protease in Onychomycosis-Related Pathogenic Trichophyton rubrum and Tinea Capitis-Related Pathogenic Trichophyton violaceum"Author names: Please confirm if the author names are presented accurately and in the correct se-quence (given name, middle name/initial, family name). Author 1 Given name: [Jingjing] Last name [Chen], Author 2 Given name: [Yangmin] Last name [Gao], Author 3 Given name: [Shuzhen] Last name [Xiong], Author 4 Given name: [Ping] Last name [Zhan]. Also, kindly confirm the details in the metadata are correct.YesPlease check and confirm the inserted city and country are correctly identified for affiliation 3.Please change the affiliations, Affiliation 2:²Jiangxi Provincial Clinical Research Center for Skin Diseases, Dermatology Hospital of Jiangxi Province,The Affiliated Dermatology Hospital of Nanchang University, Nanchang, 330200, Jiangxi; Affiliation 3: 3Institute of Clinical Medicine, Jiangxi Provincial People's Hospital, The First Affiliated Hospital of Nanchang Medical College,Nanchang 330001, Jiangxi. Thanks a lot!

Impact of climate on a host–hyperparasite interaction on Arabica coffee in its native range

Abstract Natural enemies of plant pathogens might play an important role in controlling plant disease levels in natural and agricultural systems. Yet, plant pathogen–natural enemy interactions might be sensitive to climatic changes. Understanding the relationship between climate, plant pathogens and their natural enemies is thus important for developing climate‐resilient, sustainable agriculture. To this aim, we recorded shade cover, daily minimum and maximum temperature, relative humidity, coffee leaf rust and its hyperparasite at 58 sites in southwestern Ethiopia during the dry and wet season for 2 years. Coffee leaf rust severity was positively related to the maximum temperature. Hyperparasite severity was higher when the minimum temperature was low (i.e. in places with cold night temperatures). While canopy cover did not have a direct effect on rust severity, it reduced rust severity indirectly by lowering the maximum temperature. Canopy cover had a direct positive effect on the hyperparasite severity during one surveying period. Synthesis and applications. Our findings highlight that coffee leaf rust and its hyperparasite are both affected by shade cover and temperature, but in different ways. On the one hand, these niche differences lead to the worrying prediction that levels of coffee leaf rust will increase, and its hyperparasite will decrease, with climate change. On the other hand, these niche differences between coffee leaf rust and its hyperparasite provide opportunities to develop strategies to manage the environment (such as shade cover and microclimate) in such a way that the rust is disfavoured and the hyperparasite is favoured.

Contribution of circulating monocytes in maintaining homeostasis of resident macrophages in postnatal and young adult mouse cochlea

The percentage of macrophage subpopulations based on their origins in the adult cochlea remains unclear. This study aimed to elucidate the origins of cochlear macrophages during the onset phase and development of auditory function. We used three types of mice: wildtype ICR mice, colony-stimulating factor 1 receptor (Csf1r)-deficient mice, and Ms4a3Cre-Rosa tdTomato (Ms4a3tdT) transgenic mice. Macrophages were labeled with ionized calcium-binding adapter molecule 1 (Iba1), which is specific to more mature macrophages, and CD11b, which is specific to monocyte lineage. We investigated the spatial and temporal distribution patterns of resident macrophages in the cochlea during the postnatal and early adult stages. During the adult stages, the rate of monocytes recruited from the systemic circulation increased; moreover, Iba1+/CD11b− cochlear macrophages gradually decreased with age. Fate mapping of monocytes using Ms4a3tdT transgenic mice revealed an increased proportion of bone marrow-derived cochlear macrophages in the adult stage. Contrastingly, the proportion of yolk sac- and fetal liver-derived tissue-resident macrophages decreased steadily with age. This heterogeneity could be attributed to differences in environmental niches within the tissue or at the sub-tissue levels. Future studies should investigate the role of cochlear macrophages in homeostasis, inflammation, and other diseases, including infection, autoimmune, and metabolic diseases.

Sweet complexity: O-linked protein glycosylation in pathogenic Neisseria.

The genus Neisseria, which colonizes mucosal surfaces, includes both commensal and pathogenic species that are exclusive to humans. The two pathogenic Neisseria species are closely related but cause quite different diseases, meningococcal sepsis and meningitis (Neisseria meningitidis) and sexually transmitted gonorrhea (Neisseria gonorrhoeae). Although obvious differences in bacterial niches and mechanisms for transmission exists, pathogenic Neisseria have high levels of conservation at the levels of nucleotide sequences, gene content and synteny. Species of Neisseria express broad-spectrum O-linked protein glycosylation where the glycoproteins are largely transmembrane proteins or lipoproteins localized on the cell surface or in the periplasm. There are diverse functions among the identified glycoproteins, for example type IV biogenesis proteins, proteins involved in antimicrobial resistance, as well as surface proteins that have been suggested as vaccine candidates. The most abundant glycoprotein, PilE, is the major subunit of pili which are an important colonization factor. The glycans attached can vary extensively due to phase variation of protein glycosylation (pgl) genes and polymorphic pgl gene content. The exact roles of glycosylation in Neisseria remains to be determined, but increasing evidence suggests that glycan variability can be a strategy to evade the human immune system. In addition, pathogenic and commensal Neisseria appear to have significant glycosylation differences. Here, the current knowledge and implications of protein glycosylation genes, glycan diversity, glycoproteins and immunogenicity in pathogenic Neisseria are summarized and discussed.

Combined effects of mixing ratios and tree size: how do mixed forests respond to climate and drought events?

Although the relationship between biodiversity and ecosystem functionality (BEF) has been studied comprehensively, how the mixing ratio of tree species in mixed forests affects the response of trees to climate and drought remains an unexplored and rather unknown question. Hence, we established tree-ring chronologies for Pinus tabuliformis Carr. (P) and Quercus variabilis Blume. (Q) mixed forests with different mixing ratios. In the temperate region of China, we investigated three mixing ratios: 90% P and 10% Q (P9Q1), 60% P and 40% Q (P6Q4), and 20% P and 80% Q (P2Q8). We collected tree ring samples using three tree size categories: dominant, intermediate, and suppressed trees. We explored the climate sensitivity of these trees and their drought tolerance indices-resilience (Rs), resistance (Rt), and recovery (Rc) under two drought conditions: short-term drought (1993 drought) and long-term drought (1999-2015 drought). P6Q4 made P. tabuliformis more sensitive to the Palmer drought severity index (PDSI) from the previous year than the other two ratios. The effect of the mixing ratio on drought response was insignificant under short-term drought in both tree species. Rt, Rc, and Rs of P. tabuliformis decreased with an increasing Q. variabilis:P. tabuliformis ratio in long-term drought. Rt, Rc, and Rs of Q. variabilis were the highest in P6Q4. The sensitivity of trees to PDSI varied among classes and was influenced by the mixing ratio. Dominant trees were most sensitive to PDSI in P6Q4 and P2Q8, whereas intermediate and suppressed trees were more sensitive to PDSI in P9Q1. The impact of tree size on drought tolerance indices varied according to drought type and mixing ratio. These findings showed that the mixing ratio has a confounding effect on the drought sensitivity of temperate tree species. Differences in hydrological niches allow Q. variabilis to benefit from mixing with P. tabuliformis. Mixing with optimal proportion of P. tabuliformis maximizes the drought resilience of Q. variabilis. Additionally, weakly competitive species (P. tabuliformis) do not benefit from mixed forests during prolonged water deficits. This result complements previous arguments that species mixing reduces the biological vulnerability of individuals. This study emphasizes the importance of species selection based on the biological and physiological characteristics of tree species in the afforestation of mixed forests. It highlights the critical role of species mixing ratios in the resistance of mixed forest ecosystems to climate change, which may provide a reference for sustainable forest management.

Turtle species and ecology drive carapace microbiome diversity in three seasonally interconnected wetland habitats.

Different species of freshwater turtles exhibit primary behaviours ranging from aerial basking to benthic bottom-walking, cycle between wet and dry conditions at different time intervals, and undertake short-distance overland movements between aquatic habitats. These behaviours in turn may impact the accumulation of microbes on external shell surfaces of turtles and provide novel niches for differentiation of microbial communities. We assessed microbial diversity using 16S and 18S rRNA metabarcoding on carapace surfaces of six species of freshwater turtles residing in three adjacent and seasonally interconnected wetland habitats in southeast Oklahoma (United States). Communities were highly diverse, with nearly 4200 prokaryotic and 500 micro-eukaryotic amplicon sequence variants recovered, and included taxa previously reported as common or differentially abundant on turtle shells. The 16S rRNA alpha diversity tended to be highest for two species of benthic turtles, while 18S rRNA alpha diversity was highest for two basking and one shallow-water benthic species. Beta diversity of communities was more strongly differentiated by turtle species than by collection site, and ordination patterns were largely reflective of turtle species' primary habits (i.e. benthic, basking, or benthic-basking). Our data support that freshwater turtles could play a role in microbial ecology and evolution in freshwater habitats and warrant additional exploration including in areas with high native turtle diversity and inter-habitat turtle movements.

Spatial patterns of beta diversity in marine benthic assemblages from coastal areas of southern Brazil and their implications for conservation

Beta diversity helps to understand changes in species composition over space and time, with two key components: nestedness (hierarchical pattern in richer sites) and turnover (species replacement due to niche or dispersal differences). It measures the loss or gain of species (nestedness) and species replacement (turnover) when comparing two or more spatial/temporal/environmental units. As both components require different species conservation strategies, assessing which of them the communities are organized is an important tool for this purpose. Our study aimed to evaluate which two components of beta diversity (nestedness or turnover) are responsible for structuring invertebrate and fish assemblages on the southern coast of Brazil. This region is historically recognized as a shrimp trawling area, a type of fishing with negative impacts on marine biota, such as the removal of species and habitat destruction. Our results suggest that the overall beta diversity values demonstrated a high environmental heterogeneity among the sampled areas. The most significant fraction of the general beta diversity for both assemblages is explained by the spatial turnover component. As depth increased, there was a significant rise in overall beta diversity and species turnover for fish and invertebrate assemblages. In contrast, there were no significant correlations among the nestedness component, the geographical distance and depth. In water mass conditions, fish assemblage decreased with rising chlorophyll and decreasing temperature. Elevated marine phosphate and thick sediments adversely impacted invertebrate composition. Additionally, invertebrate richness showed a positive correlation with fine sand grains. The research conducted along the southern coast of Brazil suggests the utmost importance of these regions in terms of species conservation. Here, the dominant influence of the turnover component shapes the organization of subtropical marine benthic assemblages. Furthermore, these areas receive frequent visits from migratory species, further accentuating their ecological significance.

Differences in Bacterial Co-Occurrence Networks and Ecological Niches at the Surface Sediments and Bottom Seawater in the Haima Cold Seep.

Cold seeps are highly productive chemosynthetic ecosystems in the deep-sea environment. Although microbial communities affected by methane seepage have been extensively studied in sediments and seawater, there is a lack of investigation of prokaryotic communities at the surface sediments and bottom seawater. We revealed the effect of methane seepage on co-occurrence networks and ecological niches of prokaryotic communities at the surface sediments and bottom seawater in the Haima cold seep. The results showed that methane seepage could cause the migration of Mn and Ba from the surface sediments to the overlying seawater, altering the elemental distribution at seepage sites (IS) compared with non-seepage sites (NS). Principal component analysis (PCA) showed that methane seepage led to closer distances of bacterial communities between surface sediments and bottom seawater. Co-occurrence networks indicated that methane seepage led to more complex interconnections at the surface sediments and bottom seawater. In summary, methane seepage caused bacterial communities in the surface sediments and bottom seawater to become more abundant and structurally complex. This study provides a comprehensive comparison of microbial profiles at the surface sediments and bottom seawater of cold seeps in the South China Sea (SCS), illustrating the impact of seepage on bacterial community dynamics.

Unravelling the trophic ecology of poorly studied and threatened elasmobranchs inhabiting the Persian Gulf and Gulf of Oman

Elasmobranch population declines due to human impacts have been documented at a global scale, having impacts on the functioning and structure of marine ecosystems. This situation leads to an international focus on the conservation of their populations and a key step in the management and conservation of elasmobranch populations is to understand their trophic ecology. Here, by using stable isotopes analysis, we investigated the trophic relationships, trophic niche breadth, and trophic redundancy among 21 batoids and 12 sharks inhabiting the Persian Gulf and Gulf of Oman, two productive areas of the Arabian Sea considered global elasmobranch hotspots. Isotopic results revealed differences in the trophic niche and trophic position among the elasmobranch sampled at species and at family level. For example, the batoids of the family Torpedinidae and the sharks of the family Triakidae occupied higher trophic positions and the family Glaucostegidae showed a lower trophic niche width, whereas the batoids of the family Myliobatidae or Gymnuridae, in overall, showed lower higher trophic niche width, reflecting the trophic habits described for most of the sampled species. We also provided some insights into the ecology of poorly known species, especially relevant for those that are endangered at a global or regional scale. In conclusion, we provide new information about the trophic ecology among batoids and sharks inhabiting the Persian Gulf and Gulf of Oman. This information is highly useful to study the consequences of future changes on their feeding preferences due to natural or human-related factors.

Single-Cell Polyfunctional Proteomic Profiling Reveals Temporal and Niche Differences in CD4 and CD8 T Cells in Acute Myeloid Leukemia Following PD-1 Blockade Therapy

Immune checkpoint blockade (ICB) has revolutionized solid tumor treatment by unleashing T cell cytotoxic potential, however, its effectiveness in leukemias such acute myeloid leukemia (AML) has been limited. Understanding the functional states of T cells in AML within the context of ICB is crucial to understanding its limited therapeutic potential. Here, we leveraged the IsoPlexis single cell secretome platform to assess T cell polyfunctional activity in relapsed/refractory (RelRef) AML patients treated on the phase 2 clinical trial with combination azacitidine and nivolumab (Aza/Nivo) (NCT02397720). We isolated CD4 and CD8 T cells by magnetic bead sorting from the peripheral blood (PB) and bone marrows (BMs) of 21 AML patients before (pretreatment) and after ICB (post-ICB). Isolated CD4 and CD8 cells were stimulated with CD3/CD28 agonism and functionally characterized by IsoPlexis, which measures T cell secreted cytokines, chemokines, and effector molecules at the single-cell level. In total, we characterized 52 patient samples (30 from PB and 22 from BMs). Functional CD4 and CD8 profiles were correlated with clinical and demographic characteristics of the patients. This enabled us to explore the temporal and niche differences in T cell functional states, specifically in the context of PD-1 blockade therapy, in a unique cohort of AML patients at both a pseudobulk and single-cell level. At the pseudobulk level, we observed baseline activity in the chemoattractive, effector, and regulatory functional groups was higher in both PB and BM CD8 cells compared to CD4 cells (Fig 1A), suggesting increased polyfunctionality in CD8 T cells prior to treatment. Analysis comparing pretreatment and post-ICB polyfunctionality revealed similar response patterns in CD4 and CD8 T cells in both the PB and BM spaces. Interestingly, CD4 T cells exhibited increased polyfunctional activity post-ICB in both PB and BM as compared to CD8 T cells. These findings point to an unexpected contribution of CD4 T cells with ICB therapy in AML. We employed an unbiased, unsupervised neighborhood analysis which leveraged the nearest cellular neighbor based on the log fold-change in secreted proteins between samples from distinct timepoints to reveal post-ICB CD4 and CD8 T cells aggregated into distinct cellular neighborhoods (Fig 1B). Both CD4 and CD8 analysis revealed distinct groups highlighting one group containing pre-ICB cells, and another group containing pre- and post-ICB cells. This suggests that T cell functionality is predetermined prior to ICB therapy. Comparative analysis at the single-cell level further identified higher expression of chemoattractive, inflammatory, regulatory, and stimulatory polyfunctional groups in non-responders (NR) in the BM for both CD4 and CD8 T cells, and higher expression of the chemoattractive group in NRs in the PB for CD4 cells. This suggests that BM polyfunctionality may be more critical in terms of ICB response. This study provides a novel single-cell functional analysis of T cells from both PB and BM compartments in RelRef AML patients treated with ICB. Our findings suggest the functional state of T cells in the circulating state and residence within the leukemia microenvironment are not equivalent and that there are dynamic changes of T cell functionality with ICB which has broad implications for correlative sample analysis in the ICB setting.

Cell size-dependent species sensitivity to nanoparticles underlies changes in phytoplankton diversity and productivity.

Nanoparticle pollution has been shown to affect various organisms. However, the effects of nanoparticles on species interactions, and the role of species traits, such as body size, in modulating these effects, are not well-understood. We addressed this issue using competing freshwater phytoplankton species exposed to copper oxide nanoparticles. Increasing nanoparticle concentration resulted in decreased phytoplankton species growth rates and community productivity (both abundance and biomass). Importantly, we consistently found that nanoparticles had greater negative effects on species with smaller cell sizes, such that nanoparticle pollution weakened the competitive dominance of smaller species and promoted species diversity. Moreover, nanoparticles reduced the growth rate differences and competitive ability differences of competing species, while having little effect on species niche differences. Consequently, nanoparticle pollution reduced the selection effect on phytoplankton community abundance, but increased the selection effect on community biomass. Our results suggest cell size as a key functional trait to consider when predicting phytoplankton community structure and ecosystem functioning in the face of increasing nanopollution.

Rapid migration of Mongolian oak into the southern Asian boreal forest.

The migration of trees induced by climatic warming has been observed at many alpine treelines and boreal-tundra ecotones, but the migration of temperate trees into southern boreal forest remains less well documented. We conducted a field investigation across an ecotone of temperate and boreal forests in northern Greater Khingan Mountains of northeast China. Our analysis demonstrates that Mongolian oak (Quercus mongolica), an important temperate tree species, has migrated rapidly into southern boreal forest in synchrony with significant climatic warming over the past century. The average rate of migration is estimated to be 12.0 ± 1.0 km decade-1 , being slightly slower than the movement of isotherms (14.7 ± 6.4 km decade-1 ). The migration rate of Mongolian oak is the highest observed among migratory temperate trees (average rate 4.0 ± 1.0 km decade-1 ) and significantly higher than the rates of tree migration at boreal-tundra ecotones (0.9 ± 0.4 km decade-1 ) and alpine treelines (0.004 ± 0.003 km decade-1 ). Compared with the coexisting dominant boreal tree species, Dahurian larch (Larix gmelinii), temperate Mongolian oak is observed to have significantly lower capacity for light acquisition, comparable water-use efficiency but stronger capacity to utilize nutrients especially the most limiting nutrient, nitrogen. In the context of climatic warming, and in addition to a high seed dispersal capacity and potential thermal niche differences, the advantage of nutrient utilization, reflected by foliar elementomes and stable nitrogen isotope ratios, is also likely a key mechanism for Mongolian oak to coexist with Dahurian larch and facilitate its migration toward boreal forest. These findings highlight a rapid deborealization of southern Asian boreal forest in response to climatic warming.

Effect of Gap Size and Elevation on the Regeneration and Coexistence of Abies, Betula, and Acer Tree Species in a Subalpine Coniferous Forest

Forest gaps play an important role in species regeneration and forest succession. Gap size has a primary influence on tree species coexistence and community assembly along an elevation gradient. In this study, we evaluated the regeneration and coexistence of Abies faxoniana, Betula utilis, and Acer maximowiczii at different life history stages in varied gap sizes along an elevation gradient (between 3000 and 3500 m a.s.l). We found that gap size can positively enlarge the effects of elevation on the regeneration density of the three species. In the process of regeneration from seedling to sapling, Abies had stronger regeneration capability, with regeneration niche breadths of more than 0.6 in different gap sizes. A factor analysis of mixed data indicated that regeneration density, soil nutrient contents, and air humidity were mainly related to gap size, but habitat temperature was largely determined by elevation. The connection between the species regeneration density and habitat conditions was due to differences in their regeneration niches, reflecting the selective preemption of environmental resources of different species in different life stages. Microhabitat heterogeneity, controlled by the characteristics of forest gaps along an elevation, affected the regeneration niche differences of the tree species, which contributed to the species coexistence and community assembly processes.

Niche modelling suggests low feasibility of assisted gene flow for a Neogene relict tree, Castanea sativa Mill.

Abstract: As many tree species populations are being degraded by climate change, adaptive conservation, and forest management, such as assisted gene flow (AGF), can provide the genetic variation needed to adapt to climate change. The core of this strategy is to assist the adaptation process in populations at risk of climate maladaptation by introducing individuals with beneficial alleles to cope with expected climate changes. Castanea sativa Mill. (sweet chestnut) is an essential component of natural forests in the Mediterranean and Caucasian regions, with a long history of cultivation. Current climate change may seriously threaten the long-term persistence of the species, particularly in the Caucasus region, where the largest range reductions are predicted. Here, we used Species Distribution Models (SDMs) to assess the feasibility of AGF in European and Caucasian populations of Castanea sativa. Bioclimatic variables for present (1981–2010) and future (2071–2100) conditions were obtained from the CHELSA climate database. The final models of future species ranges were averaged across three climate models (IPSL-CM6A-LR, MPIESM1-2-HR and UKESM1-0-L) and three climate change scenarios – SSP1-2.6, SSP3-7.0 and SSP5-8.5. There are marked differences in the climatic niches of the Iberian, Alpine-Apennine, Balkan, and Caucasian populations, with significant implications for AGF. The most suitable European areas for the Caucasian populations were found only in the Adriatic region. The Iberian populations were not compatible with the predicted future climate in the Caucasus in any of the scenarios tested. Suitable areas for Alpine-Apennine populations within the AGF strategy were predicted in the Colchic lowlands, the eastern Pontic mountains and the Hyrcanian forests in the SSP1-2.6 and SSP3-7.0 climate change scenarios. In contrast, the Balkan populations would be compatible at most with the western Pontic mountains and, to a lesser extent, with the Hyrcanian forests. According to the most damaging climate scenario SSP5-8.5, the potential of AGF in the Caucasus with Alpine-Apennine and Balkan populations could be very limited. Our study showed limited applicability of AGF for Castanea sativa between the European and Caucasian populations due to low climate match. Genomic modelling is needed to fully assess the feasibility of this strategy in the species.

Geographic differences in the diet and isotopic niche of Octopus hubbsorum (Cephalopoda: Octopodidae) in the Mexican Pacific

ABSTRACT Octopus hubbsorum is an important fisheries resource in the Mexican Pacific and a link among different trophic levels due to its ecological role as both predator and prey. In this study, the spatial variations in the diet, isotopic niche and trophic position of O. hubbsorum were determined by analysing digestive contents along with carbon and nitrogen stable isotopes. Octopuses were sampled from four locations, three in the Gulf of California ecoregion and one in the Mexican Pacific transition ecoregion. The diet of O. hubbsorum consisted of 11 major taxonomic groups. Crustaceans were the most important prey, although some individuals consumed high proportions of polychaetes, eggs and cephalopods. The stable isotope values showed high variation (−15.86 to −13.76‰ δ13C; 14.80–17.23‰ δ15N), reflecting signals of the base of the food web at the four locations. Differences in trophic positions and isotopic niches confirm the role of this species as a generalist predator, as it can shift among alternate food sources according to local availability. Overall, our results suggest that O. hubbsorum has a similar ecological role at all locations as a predator of crustaceans and, to a lesser extent, of molluscs and fish.

A framework of Economic-Social-Natural sustainability evaluation based on multidimensional land-use ecological niche theory: Evidence in Shendong CEBs, China

Coal-electricity base cities (CEBs) are coal-based electric energy centralized and sustained production and output cities built following China’s strategic energy layout, in regions with abundant coal resources, and by the integrated coal-electricity production model. However, CEBs are mainly located in the ecologically fragile area, and coal mining activities and anthropogenic pressures caused a series of land ecological effects such as dramatic land resources change, the alleviation of land supply and demand conflict, and land damage surrounding mining area. Currently, there is not enough research on land use in CEBs, and less attention has been paid to variation ecological system response. Aiming at this problem, the research constructed a modeling framework for evaluating the spatial and temporal evolution of land use characteristics and ecological response of CEBs land use from the perspective of “Economic-Social-Natural” by adopting methods of land transfer matrix, cluster analysis, ecological niche theory, and center of gravity model. Shendong mining area was accordingly chosen as the research region to explore the multidimensional land use dynamic evolution by bringing into the evaluating framework. Therefore, the Shendong area was accordingly chosen as the research region, and land is used as the spatial carrier to explore the evaluation effect of the model framework. The result showed that grassland played a considerable role in the procedure of land transformation with the greatest utilization degree, followed by cultivated land and used land. For ecological niche, mining land and water area dominated the core economic niche, mining land, and construction land occupied the social niche, mining land controlled mostly natural niche and comprehensive niche value. In terms of ecologically integrated and comprehensive quantitative evaluation response, the production functional area, living functional area, and ecological functional area of CEBs were also quantitatively depicted and evaluated. Ecological management should focus on the downtown area of Shenmu and optimize land use patterns by increasing vegetation cover. This study combines different types of indicators to derive regional differences in ecological niches, providing an assessment method for decision makers and stakeholders to optimize land use structure and improve the ecological benefits of CEBs.

Forest herb species with similar European geographic ranges may respond differently to climate change

Many phenological studies have shown that spring geophytes are very sensitive to climate change, responding by shifting flowering and fruiting dates. However, there is a gap in knowledge about climatic drivers of their distributions and range shifts under climate change. Here we aimed to estimate climate niche shifts for four widely distributed and common geophytes of the nemoral zone of Europe (Anemone nemorosa, Anemone ranunculoides, Convallaria majalis and Maianthemum bifolium) and to assess the threat level under various climate change scenarios. Using MaxEnt species distribution models and future climate change scenarios we found that the precipitation of the warmest quarter was the most important factor shaping their ranges. All species studied will experience more loss in the 2061–2080 period than in 2041–2060, and under more pessimistic scenarios. M. bifolium will experience the highest loss, followed by A. nemorosa, A. ranunculoides, and the smallest for C. majalis. A. ranunculoides will gain the most, while M. bifolium will have the smallest potential range expansion. Studied species may respond differently to climate change despite similar current distributions and climatic variables affecting their potential distribution. Even slight differences in climatic niches could reduce the overlap of future ranges compared to present. We expect that due to high dependence on the warmest quarter precipitation, summer droughts in the future may be particularly severe for species that prefer moist soils. The lack of adaptation to long-distance migration and limited availability of appropriate soils may limit their migration and lead to a decline in biodiversity and changes in European forests.