Decline In Species Richness Research Articles

Climate-driven distributional shifts in Chocó endemic birds of southwest Colombia

IntroductionClimate change poses a significant threat to bird communities, especially forest-dwelling and narrowly distributed species, which are expected to experience severe range contractions and higher extinction risks compared to widely distributed and open-area species. The Chocó region in southwestern Colombia, known for its rich bird endemism, is particularly vulnerable.MethodsWe analyzed potential distribution shifts for 27 endemic and near-endemic bird species in the Chocó region using eBird occurrence records and climate projections. We modeled species distributions under low and high greenhouse gas emission scenarios for 2050 and 2070, comparing these projected distributions to current forested and protected areas to evaluate future conservation needs.ResultsOur findings indicate that nearly all species are projected to lose climate-suitable areas under at least one future scenario, resulting in a regional decline in species richness. Changes in species richness are most pronounced near the Colombia-Ecuador border, suggesting a shift to higher elevations. Notably, the Scarlet-and-white Tanager (Chrysothlypis salmoni) is predicted to suffer the greatest losses in climate-suitable area, both within protected and forested regions.DiscussionThese results highlight the urgency of expanding the protected area network and conserving key forested regions to help species adapt to climate change. By providing projected distribution maps and potential range shifts, our study underscores the importance of modeling future distributions to support conservation strategies for at-risk species and the ecological services they provide in tropical montane regions.

The spatiotemporal distribution patterns and impact factors of bird species richness: A case study of urban built-up areas in Beijing, China

This study aims to investigate the distribution patterns of bird species in urban built-up areas and their impact factors from multiple dimensions, including spatiotemporal distribution, environmental changes, and anthropogenic disturbances, as well as overall distribution and local hotspots. Leveraging geographic distribution data of 383 bird species from 70 families and 21 orders, the study recorded dynamic changes in bird distribution within urban built-up areas characterized by highly heterogeneous core areas and suburban areas. It examined species distribution across different seasons and land cover types, evaluated population fluctuations based on migratory behaviors, and assessed the relative abundance of bird families and species in hotspot areas. Additionally, this study employed three tree-based machine learning algorithms—Decision Tree (DT), Random Forest (RF), and Extreme Gradient Boosting (XGBoost)—to investigate the influence of environmental factors on bird species distribution within urban built-up areas. The findings showed that, temporally, the number of observed bird species in the study area peaked in May and September, while the lowest numbers of species (54.83 %) and individuals (5.45 %) were recorded during the high-temperature period from June to August. Spatially, (1) woodlands, including stable mature forests, unstable juvenile forests, and sparse vegetation, recorded the highest frequencies of bird observations (2,053 times), bird species (369 species), and bird individuals (38,623 individuals); (2) comprehensive parks, where bird species demonstrated higher adaptability to anthropogenic disturbances, experienced a more significant decline in species richness compared to country parks; and (3) the number of bird species in hotspot areas located in the core areas, which developed earlier, has decreased annually, while the number of species in suburban areas, which developed later, has increased annually. In terms of impact factors, water area (WA), point of interest kernel density (DPOI), relative humidity (RH), green space area (GSA), and nighttime light pollution (NL) were identified as the five most important environmental factors affecting bird species richness. These results suggest that although birds exhibit some adaptability to environmental changes and anthropogenic disturbances, species distribution remains significantly impacted. This research aims to provide a planning framework for future urban development that promotes biodiversity and adaptability, thereby bolstering the resilience of urban ecosystems.

Structural and acoustic properties of urbanized landscapes adversely affect bird communities in a tropical environment

IntroductionThe rural-urban gradient serves as a valuable context for investigating the impact of urbanization on biodiversity. While previous studies have demonstrated shifts in bird communities along this gradient, our understanding of the specific impacts of individual urban components such as man-made physical structures and anthropogenic noise along this gradient remains limited, and more so, in Afro-tropical environments.MethodEmploying the point count method, we recorded birds and also determined the levels of anthropogenic noise and physical structures, across fifteen sites along the rural-urban gradient on the Jos Plateau, Nigeria. We then investigated variations in bird communities along the urbanization gradient and assessed the influence of the two urban components -anthropogenic noise and physical structures, on bird populations.ResultsThere was a decline in bird abundance and species richness along the urbanization gradient. Similarly, species common to all the urbanization categories (species present at least at one point in rural, suburban, and urban) also exhibited a decrease in abundance. The suburban area showed a greater similarity in bird community composition to the urban area than the rural area. Notably, as the level of urban development increased, numerous bird species associated with undisturbed sites gradually vanished. Both anthropogenic noise and physical structures exhibited significant negative effects on bird abundance and species richness. Interestingly, we did not find evidence to suggest that the impact of anthropogenic noise was dependent on the level of physical structures. Anthropogenic noise had a significant negative relationship with bird abundance and species richness at all levels of physical structures.DiscussionWe provide evidence that bird abundance and species richness respond negatively to urbanization-related increase in anthropogenic noise and physical structures. That the impact of anthropogenic noise on birds was independent of physical structures suggests that birds in reserved areas, including urban green areas with fewer human activities may equally be affected by noise as are birds in human-dominated areas, if noise sources are near. Overall, our research underscores the detrimental consequences of anthropogenic habitat modification, particularly the alteration of structural and acoustic properties, and emphasizes the importance of preserving undisturbed habitats and implementing ecologically mindful urban planning strategies to safeguard bird communities in the Afro-tropics.

Unveiling Macroecological Patterns of Elasmobranchs in the Eastern Pacific Ocean

ABSTRACTAimTo examine the species richness, distribution and macroecological patterns of elasmobranch assemblages across a broad latitudinal gradient in the Eastern Pacific Ocean (EPO).LocationThe study area encompasses the Pacific coast of the American continent, spanning from 65°N to 60°S, and extending from the coastline to approximately 1000 km offshore, encompassing the oceanic archipelagos.TaxonElasmobranchs.MethodsUtilising the established distribution ranges of 190 elasmobranch species (comprising 89 sharks and 101 rays), we assessed the richness and spatial distribution of these species across the EPO. Subsequently, three macroecological patterns were scrutinised: Rapoport's rule, the Mid Domain Effect with its association to Mean Sea Surface Temperature, and the correlation between body size and latitudinal distribution.ResultsThe analysis of species richness along latitudinal gradients unveiled a bimodal pattern, reaching peaks between 30° to 20°N and 10°N to 5°S. A decline in species richness was observed from tropical to polar regions. Contrary to Rapoport's Rule, Stevens' and midpoint methods demonstrated higher geographic range values at lower latitudes, diminishing towards higher latitudes. Additionally, the mid‐domain effect model exhibited a robust correlation with the mean sea surface temperature. Exploring the interspecific relationship between body size and extent of occurrence, it was found that 29 out of 190 species are more susceptible to extinction.Main ConclusionMarine elasmobranchs of the EPO defy conventional latitudinal richness patterns and deviate from Rapoport's rule. Furthermore, our findings indicate a robust correlation between observed richness and both sea surface temperature and environmental heterogeneity. The proportion of species vulnerable to human or stochastic impacts potentially leading to extirpation in relation to their geographic range was low across the majority of examined provinces.

Recent Sociocultural Changes Reverse the Long‐Term Trend of Declining Habitat Availability for Large Wild Mammals in Europe

ABSTRACTAimPeople have strongly influenced the biosphere for millennia, but how their increasing activities have shaped wildlife distribution is incompletely understood. We examined how the distribution of European large (>8 kg), wild mammals has changed in association with changing anthropogenic pressures and climate change through the Holocene.LocationEurope.MethodsWe used over 17,000 zooarchaeological records of 20 species spanning 12,000 years to develop time‐calibrated species distribution models, incorporating dynamic data on cropland extent, natural vegetation fragmentation, human population density and climate. We assessed habitat availability and potential species richness across time and within seven biogeographical regions. We also compared anthropogenic pressures at zooarchaeological record sites with present‐day habitats of remaining large mammals to evaluate recent increases in their potential for coexistence with human activities.ResultsWe found a continuous decline in potential large mammal species richness, particularly linked to changes in human population density. Most habitat loss became evident continentally after 1500 AD, but in the Atlantic and Mediterranean bioregions, habitat loss reached 20% during the Iron/Roman Ages (1000 BC–500 AD) due to increasing human population density. Climate change initially boosted species richness (+0.67 species/km2 on average) until the end of the Mesolithic but had negligible effects afterward. Today, large mammals appear to have a higher potential for coexisting with people compared to the past (e.g., herbivores today inhabit areas with a mean human population density of 95 people/km2, compared to an average of 17 people/km2 in the period 1500–2000 AD).Main ConclusionsOur study emphasizes the crucial role of anthropogenic pressures over natural climate change in determining the distribution and diversity of large mammal communities throughout history. Additionally, our results indicate that contemporary anthropogenic trends like land‐use de‐intensification and stronger conservation policies can counteract the impact of past, higher anthropogenic pressures and reverse defaunation.

Can microplastics variability drive the colonization dynamics of periphytic protozoan fauna in marine environments?

In recent years, microplastics have become a global environmental hot topic of concern. To explore the effects of different concentrations of microplastics on colonization dynamics of periphytic protozoan fauna, a 21-day study was conducted in temperature-controlled circulation systems. Periphytic protozoan communities were used as test organisms and exposed to five concentrations of MPs: 0, 1, 5, 25, and 125 mg l−1, identification and enumeration were conducted on days 3, 5, 7, 10, 14 and 21. The results showed that the colonization dynamics were driven by MPs and significantly shifted at concentrations over 5 mg l−1. However, a notable decline in maximum species richness and abundance was observed in the high concentrations of microplastic, along with significant deviations in colonization patterns from the control group (0 mg l−1). Therefore, it is suggested that the colonization dynamics of periphytic protozoa can serve as a bioindicator for assessing microplastic concentrations in marine environments.

Rapid declines in freshwater gastropods in Pune city, India

ABSTRACT We studied freshwater gastropod fauna in a heavily urbanized region in tropical India, across a range of habitat types. A total of 16 species were found from a two-year survey, which is a decline of 27% compared to studies completed in the 1970s. Planorbidae was the most species rich family in the collection, with five species. Racesina luteola (Lamarck, 1822) was the most commonly occurring species in the collection. Three non-native species, including Pomacea diffusa (Blume, 1957), are also reported. Habitat type influenced species occurrences, although lentic and lotic habitats were largely similar in their fauna. Many species reported previously were missing from the current survey, along with an increased incidence of non-native species which were absent from earlier reports. This decline in species richness, particularly of native species, alongside an increased incidence and spread of non-native species in the region, highlights the impact of urbanization on the freshwater gastropod community.

Understory plant biodiversity is inversely related to carbon storage in a high carbon ecosystem.

Given that terrestrial ecosystems globally are facing the loss of biodiversity from land use conversion, invasive species, and climate change, effective management requires a better understanding of the drivers and correlates of biodiversity. Increasingly, biodiversity is co-managed with aboveground carbon storage because high biodiversity in animal species is observed to correlate with high aboveground carbon storage. Most previous investigations into the relationship of biodiversity and carbon co-management do not focus on the biodiversity of the species rich plant kingdom, which may have tradeoffs with carbon storage. To examine the relationships of plant species richness with aboveground tree biomass carbon storage, we used a series of generalized linear models with understory plant species richness and diversity data from the USDA Forest Service Forest Inventory and Analysis dataset and high-resolution modeled carbon maps for the Tongass National Forest. Functional trait data from the TRY database was used to understand the potential mechanisms that drive the response of understory plants. Understory species richness and community weighted mean leaf dry matter content decreased along an increasing gradient of tree biomass carbon storage, but understory diversity, community weighted mean specific leaf area, and plant height at maturity did not. Leaf dry matter content had little variance at the community level. The decline of understory plant species richness but not diversity to increases in aboveground biomass carbon storage suggests that rare species are excluded in aboveground biomass carbon dense areas. These decreases in understory species richness reflect a tradeoff between the understory plant community and aboveground carbon storage. The mechanisms that are associated with observed plant communities along a gradient of biomass carbon storage in this forest suggest that slower-growing plant strategies are less effective in the presence of high biomass carbon dense trees in the overstory.

Species Richness and Similarity of New Zealand Mayfly Communities (Ephemeroptera) Decline with Increasing Latitude and Altitude.

The distribution of species in relation to latitude and altitude is of fundamental interest to ecologists and is expected to attain increasing importance as the Earth's climate continues to change. Species diversity is commonly greater at lower than higher latitudes on a global scale, and the similarity of communities frequently decreases with distance. Nevertheless, reasons for such patterns are not well understood. We investigated species richness and changes in community composition of mayflies (Ephemeroptera) over 13 degrees of latitude at 81 locations throughout New Zealand by light-trapping and the benthic sampling of streams. Mayflies were also sampled along an altitudinal gradient on a prominent inactive volcano in the east of North Island. Sampled streams were predominantly in the native forest, at a wide range of altitudes from sea level to c. 1000 m a. s. l. A total of 47 of the 59 described New Zealand mayflies were recorded during the study, along with five undescribed morphospecies. Species richness declined and the degree of dissimilarity (beta diversity) of mayfly communities increased significantly from north to south but less strongly with increasing altitude. Our results suggest that the southward decline in species richness has historical origins with the north of the country having acted as a major refuge and region of speciation during the Pleistocene. The increasing dissimilarity of the northern and southern communities may reflect an increasingly harsh climate, variable amounts of subsequent southward dispersal of northern species and, in the South Island, the presence of species which may have evolved in the newly uplifted mountains during the Miocene-Pliocene.

Redistribution of vocal snapping shrimps under climate change

A variety of marine organisms can produce sounds that are important components of the marine soundscape and play a critical role in maintaining marine biodiversity. Climate change has greatly altered the geographical ranges of many marine species, including sound-producing organisms. However, the direction and the magnitude of the potential impact of climate change on the geographical distribution of sound-producing marine organisms in future remain largely unknown. To address this knowledge gap, we selected snapping shrimp, one of the most well-known marine sound-producing organisms, as a model species and explored their redistribution under climate change via species distribution models. We aimed to predict the redistribution of snapping shrimps under climate change and identify the influencing factors, which have important implications for marine conservation. Our models exhibited good discrimination abilities and identified maximum temperature as the most influential predictor of snapping shrimp distribution. Model predictions suggested that species richness is higher in tropical and temperate coastal waters and peaks in the Indo-Pacific region. The majority of snapping shrimp species are expected to respond to the changing climate by shifting their geographical ranges to deeper waters and higher latitudes. Our results showed that, in the future, high-latitude species were more likely to experience range expansion, whereas low-latitude species might experience range contraction. Moreover, the Central Indo-Pacific are predicted to suffer the biggest decline in species richness, whereas areas such as the coastal waters of southern Australia and northern China might serve as climate refuges for snapping shrimps in the future. In summary, this study highlights the potential effects of climate change on the distribution of sound-producing snapping shrimps, which may result in cascading effects on marine ecosystems.

Post-Burn, Post-Flood Effects In A Degraded Grassland, Lake Texoma, Bryan County, Oklahoma

Plant communities change over time, sometimes leading to an increase or decrease in biological diversity. Often, absence of active management of a site leads to its degradation including loss of native species and invasion by non-native weeds. Lake Texoma, Texas and Oklahoma, represents an area where extensive landscape change has happened over the course of almost a century. The Denison Dam was completed in 1938, forming the lake, which over time has altered conditions in the forested and formerly-grazed locations surrounding it. The location studied in this paper is a 186-ha tract of land situated between Johnson Creek and the Roosevelt Bridge in Bryan County, Oklahoma. In summer 2000, a species list was compiled for a grassland located at the lake site as part of a larger study. This grassland comprised ~10% of the total site area. Following two major floods and an extended drought, the site was resampled in 2018. Results indicated it had suffered a serious decline in species richness and an increase in abundance of invasive or encroaching species. Species richness was reduced by approximately 50% between 2000 and 2018. Fewer transects were sampled in 2018 because of woody encroachment on the original site. In spring 2021, following an extensive prescribed burn, the site was resampled to see if burning led to any reduction in undesirable species. The most frequent species in 2000 included Panicum philadelphicum, Lespedeza virginica, Rudbeckia hirta and Ambrosia psilostachya and in 2018 they were Lespedeza cuneata, Ambrosia psilostachya, and Dichanthelium oligosanthes. It is possible that the invasive Lespedeza cuneata (sericea lespedeza) spread after a 2007 flood because of some combination of reduced competition and transport of seed in floodwater. In 2021, the most frequent species were the same as in 2018, showing little effect of the burn. However, the Shannon diversity and evenness in both early and late summer sampling periods after the burn were higher than those for the 2018 data, suggesting that the burn may have had some effect. To attempt to restore the site to more “native” conditions would probably require some combination of regular burning, flash grazing, and possibly herbicide use. Once sericea lespedeza establishes, it is very difficult to eradicate from a location.

Bioclimatic and remote sensing factors are better key indicators than local topography and soil: Vegetation composition variability in forests of Pakistan's Spin Ghar Mountain range

The composition, structure and distribution of vegetation are influenced by diverse environmental factors. Such research inquiries provide the initial data for future conservation and management efforts. The study area of North Waziristan district, Khyber Pakhtunkhwa, Pakistan comprises diverse forests of the Spin Ghar Mountain Range (at the border areas of Pakistan and Afghanistan), and a highly remote, mountainous, and unexplored region. There was little information on the complex relationships that existed between the study area's ambient environment and vegetation. This study hypothesized that the varying environmental complexity in the study area and vegetation variety may be significantly correlated, and the ranking of leading influencing factors might enhance our ecological understanding. A total of 61 study sites comprising 183 transects (50 m each) were randomly selected to record the vegetation-environment data from January-2018 to December-2020 (3 years). Monte Carlo permutation testing, hierarchical clustering of study samples, indicator species analysis, and ordination were applied to assess the sampling data. The results indicated that there were a total of 391 vascular plant species which were further classified into seven significantly different (p < 0.05) plant assemblages, each comprising of a distinct species makeup. A variety of different environmental variables (topographic (06), bioclimatic (19), edaphic (09), remote sensing, and anthropogenic predictors (16)) were considered. Simple term effects testing results depicted the significant (p(adj) < 0.05) role of 39 variables initially, whereas, conditional term effects testing (with variance inflation factor (VIF) threshold value of < 10, and forward selecting variables that provided the most unique information) results highlighted the prominent role of eight (08) contributors. The results of the latter analysis ranked the mean temperature of the warmest quarter (Bio10) as the most influencing factor, followed by Normalized Difference Vegetation Index (NDVI), longitude, continuous heat insulation load index (CHILI), precipitation of the warmest quarter (Bio18), global human modification of the terrestrial systems (gHM), organic carbon density (OCD), and annual precipitation (Bio12). This study concluded that the vegetation variability in the study area was significantly correlated with the prevailing environment, and considered bioclimatic and remote sensing factors were better key indicators for any vegetation distribution when the study was conducted on a large spatial scale. Based on these results, the anticipated future variations in climate, particularly global warming, lengthy drought spells, and population explosion might remarkably lead to decline in local plant species richness and distribution. For the study area to guard its priceless biodiversity for future generations, careful and prompt conservation and management planning are required.

Vegetation dieback in the Mississippi River Delta triggered by acute drought and chronic relative sea-level rise

Vegetation dieback and recovery may be dependent on the interplay between infrequent acute disturbances and underlying chronic stresses. Coastal wetlands are vulnerable to the chronic stress of sea-level rise, which may affect their susceptibility to acute disturbance events. Here, we show that a large-scale vegetation dieback in the Mississippi River Delta was precipitated by salt-water incursion during an extreme drought in the summer of 2012 and was most severe in areas exposed to greater flooding. Using 16 years of data (2007–2022) from a coastwide network of monitoring stations, we show that the impacts of the dieback lasted five years and that recovery was only partial in areas exposed to greater inundation. Dieback marshes experienced an increase in percent time flooded from 43% in 2007 to 75% in 2022 and a decline in vegetation cover and species richness over the same period. Thus, while drought-induced high salinities and soil saturation triggered a significant dieback event, the chronic increase in inundation is causing a longer-term decline in cover, more widespread losses, and reduced capacity to recover from acute stressors. Overall, our findings point to the importance of mitigating the underlying stresses to foster resilience to both acute and persistent causes of vegetation loss.

Short-Interval, High-Severity Wildfire Depletes Diversity of Both Extant Vegetation and Soil Seed Banks in Fire-Tolerant Eucalypt Forests

Many plant species are well-adapted to historical fire regimes. An increase in the severity, frequency, and extent of wildfires could compromise the regenerative capacity of species, resulting in permanent shifts in plant diversity. We surveyed extant vegetation and soil seed banks across two forest types with contrasting historical fire regimes—Shrubby Dry Forest (fire return interval: 10–20 years) and Sub-Alpine Woodland (50–100 years). Over the past 20 years, both forests have been subject to repeated, high-severity wildfires at intervals significantly shorter than their historical return intervals. We examined the soil seed bank response to fire-cued germination, and whether the plant diversity in soil seed banks and extant vegetation demonstrated similar responses to short-interval, high-severity wildfires. The soil seed bank demonstrated a positive response to heat in combination with smoke, and for the Sub-Alpine Woodland, this was limited to sites more frequently burnt by fire. With an increase in fire frequency, there was a decline in species richness and Shannon’s Diversity and a shift in species composition in both extant vegetation and the soil seed bank. The fire frequency effects on the relative richness of trait associations were restricted to the Shrubby Dry Forest, and included an increase in short-lived obligate seeders, wind-dispersed species, and ant-dispersed shrubs in burnt relative to long unburnt sites in both extant vegetation and the soil seed bank. Graminoids were the most abundant component of the soil seed banks of Sub-Alpine Woodlands, and this increased with more frequent fire, with a similar trend (p = 0.06) in extant vegetation. Clear shifts in plant diversity in both soil seed banks and extant vegetation in forest types with contrasting historical fire regimes suggest that emerging fire regimes are pushing ecosystems beyond their historical range of variability, including potentially more flammable states and a decline in the buffering capacity of soil seed banks.

Shifting mammal communities and declining species richness along an elevational gradient on Mount Kenya.

Conservation areas encompassing elevation gradients are biodiversity hotspots because they contain a wide range of habitat types in a relatively small space. Studies of biodiversity patterns along elevation gradients, mostly on small mammal or bird species, have documented a peak in diversity at mid elevations. Here, we report on a field study of medium and large mammals to examine the impact of elevation, habitat type, and gross primary productivity on community structure. Species richness was observed using a camera trap transect with 219 sites situated across different habitat types from 2329 to 4657 m above the sea level on the western slope of Mt Kenya, the second highest mountain in Africa. We found that the lowest elevation natural habitats had the highest species richness and relative abundance and that both metrics decreased steadily as elevation increased, paralleling changes in gross primary productivity, and supporting the energy richness hypothesis. We found no evidence for the mid-domain effect on species diversity. The lowest elevation degraded Agro-Forestry lands adjacent to the National Park had high activity of domestic animals and reduced diversity and abundance of native species. The biggest difference in community structure was between protected and unprotected areas, followed by more subtle stepwise differences between habitats at different elevations. Large carnivore species remained relatively consistent but dominant herbivore species shifted along the elevation gradient. There was some habitat specialization and turnover in species, such that the elevation gradient predicts a high diversity of species, demonstrating the high conservation return for protecting mountain ecosystems for biodiversity conservation.

Identification of temporal shifts of oral bacteria in bone regeneration following mandibular bone defect injury and therapeutic surgery in a porcine model.

Considered the second largest and most diverse microbiome after the gut, the human oral ecosystem is complex with diverse and niche-specific microorganisms. Although evidence is growing for the importance of oral microbiome in supporting a healthy immune system and preventing local and systemic infections, the influence of craniomaxillofacial (CMF) trauma and routine reconstructive surgical treatments on community structure and function of oral resident microbes remains unknown. CMF injuries affect a large number of people, needing extensive rehabilitation with lasting morbidity and loss of human productivity. Treatment efficacy can be complicated by the overgrowth of opportunistic commensals or multidrug-resistant pathogens in the oral ecosystem due to weakened host immune function and reduced colonization resistance in a dysbiotic oral microbiome. To understand the dynamics of microbiota's community structure during CMF injury and subsequent treatments, we induced supra-alveolar mandibular defect in Hanford miniature swine (n=3) and compared therapeutic approaches of immediate mandibullar reconstructive (IMR) versus delayed mandibullar reconstructive (DMR) surgeries. Using bacterial 16S ribosomal RNA gene marker sequencing, the composition and abundance of the bacterial community of the uninjured maxilla (control) and the injured left mandibula (lingual and buccal) treated by DMR were surveyed up to 70-day post-wounding. For the injured right mandibula receiving IMR treatment, the microbial composition and abundance were surveyed up to 14-day post-wounding. Moreover, we measured sera level of biochemical markers (e.g., osteocalcin) associated with bone regeneration and healing. Computed tomography was used to measure and compare mandibular bone characteristics such as trabecular thickness between sites receiving DMR and IMR therapeutic approaches until day 140, the end of study period. Independent of IMR versus DMR therapy, we observed similar dysbiosis and shifts of the mucosal bacteria residents after CMF injury and/or following treatment. There was an enrichment of Fusobacterium, Porphyromonadaceae, and Bacteroidales accompanied by a decline in Pasteurellaceae, Moraxella, and Neisseria relative abundance in days allotted for healing. We also observed a decline in species richness and abundance driven by reduction in temporal instability and inter-animal heterogeneity on days 0 and 56, with day 0 corresponding to injury in DMR group and day 56 corresponding to delayed treatment for DMR or injury and immediate treatment for the IMR group. Analysis of bone healing features showed comparable bone-healing profiles for IMR vs. DMR therapeutic approach.

Cerrado bat community assembly is determined by both present‐day and historical factors

AbstractAimTo investigate the influence of ecological factors, geologic and climatic history on current diversity patterns of bat communities. We predicted that (i) our three different biodiversity dimensions (species richness, functional and phylogenetic diversity) will have a positive relationship with habitat heterogeneity; (ii) variation in phylogenetic diversity will be positively influenced by elevation; (iii) biodiversity dimensions will be influenced by climatic stability, with less diversity in regions with higher climatic instability.LocationNeotropical Savannah (Cerrado).MethodsWe calculated nine metrics: species richness, functional diversity, phylogenetic diversity, mean paired functional distance (MFD) and phylogenetic distances (MPD), richness‐corrected functional diversity (SES‐FD), richness‐corrected phylogenetic diversity (SES‐PD) and richness‐corrected mean functional and phylogenetic distances (SES.MFD and SES.MPD) using distribution records for 111 bat species. Habitat heterogeneity, climatic variables, elevation, floristic and climatic stability were used as independent variables. We used hierarchical Bayesian models to spatialise biodiversity dimensions based on the best predictors.ResultsCerrado habitat heterogeneity is important for phylogenetic diversity and mean functional and paired phylogenetic distances. Precipitation, temperature, elevation, habitat heterogeneity, and climatic stability were the most important predictors of Cerrado bat biodiversity. Species richness is inversely related to climatic instability, which is the best predictor of this metric. There is a decline in species richness in regions where the floristic composition has been more altered during the last 30,000 years, mainly in southern Cerrado.Main ConclusionsPresent‐day and historical factors simultaneously explain the biodiversity dimensions of bat communities in the Cerrado. Habitat heterogeneity is a major driver of phylogenetic diversity of Cerrado bats, and species of closely related lineages share habitats with homogeneous vegetation. Cerrado climatic changes and geologic history influenced the observed diversity metrics (PD and FD) and the ones corrected for species richness (SES‐PD and SES‐FD) in opposite ways. Species richness corrected metrics (SES‐PD and SES‐FD) indicate that species filtered by adaptive traits mainly occupied regions of climatic instability.

Plant–soil feedback is dependent on tree mycorrhizal types and tree species richness in a subtropical forest

Plant-soil feedback (PSF) is an important driver of plant species coexistence and diversity maintenance. However, it remains unclear how changes in PSF due to decline in tree species richness influence the performance of arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) tree species. A PSF experiment was established with eight target tree species (four AM and four EcM tree species) based on a subtropical forest Biodiversity-Ecosystem Functioning Experimental in China (BEF-China) platform, where soil inocula were collected beneath the canopy of target tree species individuals growing in monoculture and eight tree-species mixture plots. We hypothesized that the negative PSF strength of AM tree species would be stronger in monocultures than that in eight tree-species mixtures, resulting in better performance in highly diverse plant communities, whereas EcM tree species would benefit less from tree species richness. However, the results showed consistent PSFs of AM tree species regardless of tree species richness. In contrast, EcM tree species experienced a change from positive in monocultures to negative PSF in eight tree-species mixtures, influencing the performance of EcM tree seedlings. With high concern of the cascading effects of tree species richness on PSFs via modulating soil fungal communities, we revealed that the alterations in EcM fungal abundance, putatively pathogenic fungal diversity, and fungal co-occurrence network complexity mirrored those of PSF associated with EcM tree species, showing the changes from positive in monocultures to negative feedback in eight tree-species mixtures. Our findings highlight the differential PSFs exhibited by AM and EcM tree species in response to tree species richness, and provide insight into the potential role of fungal functional guilds and co-occurrence network complexity in shaping the PSFs of them.

Annual and decadal surveys of molluscs on intertidal platform reefs in a warming marine environment in the southeastern Indian Ocean provide a baseline for monitoring for future environmental changes

ABSTRACT Few data sets are available to evaluate short- and long-term perturbations and impacts of increasing anthropogenic stresses and a warming marine environment in coastal regions near cities. The Perth, Western Australia shoreline has extensive, depauperate sandy beaches interrupted by small, biodiverse intertidal reef platforms. We present transect data on mollusc diversity and density on three Perth platforms recorded from 1983 to 1987, and compare it to 2007 and 2021 to analyse assemblage modifications in response to increased anthropogenic pressures. NMDS multivariate analysis showed a consistent drift in assemblage composition in 2007 and 2021, but this is was not statistically significant from the 1980s baseline (PERMANOVA, P = 0.336). There was no significant long-term decline (or increase) in molluscan species richness. Most species were uncommon but eight were recorded on at least 20 of the 21 surveys. The endemic Western Australian mussel Brachidontes ustulatus (Lamarck, 1819) accounted for 71.8% of all individuals. Total mollusc density varied primarily with changes in B. ustulatus. Tropical species were a minor component of the molluscs that did not change in diversity with warming temperatures. These data provide a long-term baseline for monitoring future anthropogenic changes.

Latitudinal richness patterns in a temperate forest region: disentangling the effects of evenness, density and aggregation

It is well known that species diversity declines with increasing latitude. However, the underlying causes and mechanisms remain ambiguous due to effects of scale, the shape of the species abundance distributions (SAD), the total number of individuals (N) and the spatial aggregation of individuals (AGG). In this study, we examine how SAD, N and AGG contribute to the latitudinal richness gradient. Our study is based on a dataset that includes tree, shrub, and herbaceous plants collected from 445 permanent forest plots scattered across an expansive temperate forest region, covering latitudes from 39.71°N to 53.37°N. We compared multiple diversity patterns along the latitude between three life forms (trees, shrubs and herbs) and analyzed the effects of SAD, N and AGG on the latitudinal richness gradient. Our results reveal a general decline in most diversity measures along the latitudinal gradient, with the exception of herbaceous plants. Furthermore, we observed consistent effects of AGG and SAD on the latitudinal richness gradient across all three life forms. Specifically, a decreasing species evenness with increasing latitude led to a reduction in richness, while the simultaneous decrease in spatial aggregation, along with the effects of total number of individuals, collectively contributed to the decline in species richness with increasing latitude. However, the effect of total abundance varies among life forms, with a negligible effect on tree richness, a negative effect on shrub richness, and a significantly positive effect on herbaceous richness. These findings highlight the dependency of the “more-individuals hypothesis” on specific life forms. Our study shows that decomposing species richness into community structure components provides an opportunity for linking specific processes to latitudinal diversity gradients.