Reduced Species Richness Research Articles

Predicting biodiversity loss in island and countryside ecosystems through the lens of taxonomic and functional biogeography

We investigate how variation in patch area and forest cover quantified for three different spatial scales (buffer size of 500, 1500 and 3000 m radius) affects species richness and functional diversity of bat assemblages in two ecosystems differing in fragment–matrix contrast: a landbridge island system in Panama and a countryside ecosystem in the Brazilian Amazon. Bats were sampled on 11 islands and the adjacent mainland in Panama, and in eight forest fragments and nearby continuous forest in Brazil. Species–area relationships (SAR) were assessed based on Chao1 species richness estimates, and functional diversity–area relationships (FAR) were quantified using Chao1 functional diversity estimates measured as the total branch length of a trait dendrogram. FARs were calculated using three trait sets: considering five species functional traits (FARALL), and trait subsets reflecting ‘diet breadth’ (FARDIET) and ‘dispersal ability’ (FARDISPERSAL). We found that in both study systems, FARALL was less sensitive to habitat loss than SAR, in the sense that an equal reduction in habitat loss led to a disproportionately smaller loss of functional diversity compared to species richness. However, the inhospitable and static aquatic matrix in the island ecosystem resulted in more pronounced species loss with increasing loss of habitat compared to the countryside ecosystem. Moreover, while we found a significant FARDISPERSAL for the island ecosystem in relation to forest cover within 500 m landscape buffers, FARDIET and FARDISPERSAL were not significant for the countryside ecosystem. Our findings highlight that species richness and functional diversity in island and countryside ecosystems scale fundamentally differently with habitat loss, and suggest that key bat ecological functions, such as pollination, seed dispersal and arthropod suppression, may be maintained in fragments despite a reduction in species richness. Our study reinforces the importance of increasing habitat availability for decreasing the chances of losing species richness in smaller fragments.

Threshold changes in the structure and composition of bush clumps in piospheres in an arid thicket mosaic, South Africa

Arid Thicket transformation by domestic meso-herbivores is purported to follow a state-and-transition model. Our study represents a first attempt to verify this hypothesis in Pruim-Spekboomveld, a variation of Arid Thicket. We correlate structural and compositional attributes of thicket bush clumps to distance from artificial watering points in four piosphere treatments that have had a different rangeland management history. We fit linear, exponential and sigmoid regression models to our data and use Akaike's Information Criterion to select the best fitting model. Furthermore, we compare the end regions of our data in the piosphere treatments to each other and to similar data collected in a transformed and untransformed reference site. We use both the pattern and extent of transformation within and between the treatments and the reference sites, to verify the existence of stable states and ecological thresholds. Our results indicate a threshold reduction in species richness, functional type diversity, succulent shrub diversity, succulent shrub cover and palatable shrub cover; and a corresponding threshold increase in perennial alien invasive and ephemeral forb cover; with an increase in herbivore-induced transformation. These findings suggest that our treatments have crossed a degradation threshold and therefore represent an alternative stable state to the untransformed reference site.

Nitrogen alters effects of disturbance on annual grassland community diversity: Implications for restoration

Abstract In an era of anthropogenically altered disturbance regimes and increased nutrient loads, understanding how communities respond to these perturbations is essential for successful habitat restoration. Disturbance and resource supply can affect community diversity by altering community assembly processes, such as recruitment, mortality or competitive inequalities. The mechanisms behind community responses to these drivers will differentially affect multiple facets of diversity. Here we examine how factorial manipulations of disturbance (raking to remove above‐ground vegetation) and nitrogen supply affect taxonomic and phylogenetic diversity of predominantly annual California grassland communities spanning a 500‐km latitudinal and twofold rainfall gradient. The disturbance caused density‐independent biomass removal and increased access to resources such as space and light, thus mimicking demographic effects of disturbance as considered in ecological models and broadly applicable to empirical systems. We used paired metrics of richness, evenness and community composition to compare evidence from taxonomy and phylogeny. Disturbance increased species and phylogenetic diversity (richness and evenness metrics). However, nitrogen addition interacted with disturbance to reduce species richness and phylogenetic diversity. Undisturbed communities were more strongly clustered phylogenetically, but disturbance eroded this clustering such that communities became more random (i.e. indistinguishable from a null model of assembly). Species composition differed between disturbed and undisturbed communities, and many species were observed in only one community type. Disturbance interacted with nitrogen supply to alter phylogenetic composition of communities, and recently disturbed communities were more spatially variable in phylogenetic composition than undisturbed communities. Phylogenetic composition of communities also differed among nitrogen treatments. Synthesis. Our results suggest that disturbing these grassland communities by removing above‐ground vegetation increased community diversity by increasing recruitment. Seed addition following this type of disturbance is thus likely to be an effective restoration technique. However, we have shown that disturbance combined with nitrogen enrichment reduces community diversity. The mechanism for this enrichment effect does not appear to be linked to increased productivity leading to light limitation. This work suggests restoration efforts employing biomass removal must take nutrient availability into account to maximize local community diversity.

Litter addition decreases plant diversity by suppressing seeding in a semiarid grassland, Northern China.

Plant community diversity is conducive to maintain the regional ecosystems stability and ecosystem services. Seed germination is one of the main ways to regulate plant diversity, owing to seedling recruitment as a basis for plant community renewal. However, the exact mechanism of how plant litter affects seedling recruitment, and species richness is not yet fully understood. Therefore, a litter addition and removal experiment was established in a semiarid grassland to study the effects of plant litter on seedling recruitment and species richness from April to August in 2016 and 2017 in Northern China. The positive correlation between species richness and seedling recruitment indicated that a guarantee of seedling recruitment was the main precondition to protect species richness. Adding rather than removing litter significantly reduced species richness. Litter addition inhibited species richness by directly increasing mechanical damage or indirectly reducing photosynthetically active radiation and seedling recruitment. The results of this study are conducive to understand the evolutionary and regulatory mechanisms of community species richness and seedling recruitment in grassland ecosystems after adding or removing plant litter.OPEN RESEARCH BADGES This article has been awarded Open Data, Open Materials and Preregistered research design Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.5061/dryad.5dj3jg5 and http://doi.org/10.5061/dryad.13gj03s

Land management modulates the environmental controls on global earthworm communities

AbstractAimSoils and their biological communities face increasing pressure from multiple global drivers, including land management and climate change. In soils, earthworms play key roles in ecosystem functioning, but the environmental controls on their global communities are not fully understood. Here, an earthworm dataset was compiled to investigate the effects of environmental variables and land management on global earthworm communities.Location40° S–65° N.Time period1962 to 2016.Major taxa studiedEarthworms.MethodsA dataset of 899 earthworm community observations, together with environmental variables, was compiled across 169 globally distributed sites. Sites included natural forest and grassland or managed arable, pasture and plantation ecosystems. Total, anecic, endogeic and epigeic abundances and total species richness were compared in natural and managed ecosystems to quantify the effects of land management across climates. A hierarchical model was used to test the importance of environmental controls in predicting the relationship between total earthworm species richness and abundance at a global scale.ResultsLand management prompted little change in total earthworm abundance at the global scale, but reduced species richness and shifted community composition. Endogeic earthworms were more abundant in managed ecosystems, while anecic and epigeic earthworms showed variable responses across ecosystem types. Global relationships between total earthworm species richness and abundance were explained by climate, soil pH and land management.Main conclusionsLand management modulates the effects of environmental controls on global earthworm communities, through direct disturbance and indirect changes in edaphic conditions.

Vertical size structure is associated with productivity and species diversity in a short‐stature grassland: Evidence for the importance of height variability within herbaceous communities

AbstractQuestionsLocal size structure is frequently measured in plant populations and forested systems due to its association with population‐ and community‐level processes. In contrast, size structure is rarely examined within herbaceous communities despite evidence for size‐dependent processes in these systems, suggesting an important functional vegetation property may be widely overlooked. Here, we test whether vertical size structure (a) varies within a short‐stature grassland, (b) varies along a productivity gradient, and (c) enhances the understanding of a foundational ecological pattern: the diversity–productivity relationship.LocationRough fescue grassland in Alberta, Canada.MethodsWe measured the heights of individuals within 32 plots and used average height, the Gini coefficient, and a two‐parameter Weibull distribution to estimate community‐level vertical size structure. Linear mixed models were used to test whether size structure parameters were significantly associated with productivity, species richness, and species evenness.ResultsVertical size structure varied significantly among local communities, such that some were dominated by short individuals while others were comprised of a more equal number of taller individuals. With increasing productivity, there was an increase in average plant height and a decrease in height inequality. Decreased height inequality was associated with reduced species richness with evidence that loss was not size‐dependent. The inclusion of vertical size structure parameters increased the explained variance of the diversity–productivity relationship by ~35% while also increasing its parsimony.ConclusionsEven within a short‐stature grassland, there is substantial functional variation in vertical size structure. Productivity is strongly associated with size structure patterns, and the inclusion of height inequalities greatly enhances productivity–diversity relationships, likely because they are the product of assembly mechanisms such as size‐asymmetric competition, assemblage‐level thinning, and niche complementarity. Overall, this demonstrates that vertical size structure has been a missing mechanism in most community assembly theories and models and should be included in the future.

Earthworm communities in conventional and organic fruit orchards under two different climates

Climate strongly influences the distribution of soil organisms in agroecosystems, but local agricultural practices can also alter the natural composition of soil communities. Conventional (CONV) practices usually cause long-term negative effects in soil agroecosystems, by reducing soil biodiversity and altering edaphic processes, while organic (ORG) practices promote soil health and the diversity and abundance of fauna. Here, we used distributional and multivariate analyses to compare the species composition and ecological structure of earthworm communities in four fruit orchards (kiwifruit, grapevine, clementine, and olive) cultivated under CONV and ORG practices and located in two different biogeographic regions of the Iberian Peninsula (Atlantic and Mediterranean). Results indicated that the interaction among the three factors studied (biogeographic region, agricultural management and fruit tree orchard) caused a significant effect on all parameters analyzed (abundance, biomass, diversity, earthworms communities, and earthworms life strategies). More earthworms were collected in Atlantic (7160 ind m−2) than Mediterranean (5576 ind m−2) region, although no differences were found between CONV and ORG practices. However, agricultural practices caused an important effect on earthworm diversity, with significant reductions in species richness (S), diversity (H′ index) and mature earthworms in the dryer and warmer climate under CONV practices. The multivariate analysis reflected those dissimilarities in ecological structure between biogeographic regions (95%) and agricultural practices (>82%). Finally, the comparison of the abundance and biomass curves confirmed that ORG practices were beneficial for earthworm populations, showing moderate or absence of ecological perturbation, and consequently, they diverted more energy to individual growth than to reproduction. Therefore, the positive effects of implementing more sustainable agricultural practices in agroecosystems will depend on their interactive effects with environmental factors, being especially useful in the dryer and warmer climates, such as in the Mediterranean region.

Long-term responses of desert ant assemblages to climate.

Productivity is a key driver of ecosystem structure and function, so long-term studies are critical to understanding ecosystems with high temporal variation in productivity. In some deserts, productivity, driven by moisture availability, varies immensely over time (rainfall) and space (landscape factors). At high productivity, species richness is expected to be driven in opposing directions by abundance (More Individuals Hypothesis - MIH) and competition. While studies investigating the impacts of spatial variation in productivity on community structure are common, the impacts of temporal variability on productivity are poorly understood. We tested how well rainfall predicted the activity, species numbers and assemblage composition of ants and if responses were moderated by landscape position. We also asked whether the number of species (richness per sampling unit and estimated species richness) responded directly to rainfall or was moderated by ant activity or competition from dominant ants. Over a 22-year period, when annual rainfall fluctuated between 79mm and 570mm, we sampled ants using pitfall traps in paired dune and swale habitats in the Simpson Desert, Australia. We used climate records over this period to model changes in ant assemblages. Activity of dominant ants responded primarily to long-term rainfall, increasing exponentially, while subordinate ants responded to short-term weather and time. Consistent with the MIH, the number of ant species was best predicted by activity, particularly that of subordinate ants. Activity of dominant ants had a declining positive effect on numbers of species. Landscape position strongly predicted species composition, while long-term rainfall determined composition at genus level but not species level. Over time, species composition fluctuated, but several genera consistently increased in activity. Productivity moderators such as long-term rainfall and landscape position are key drivers of ant activity and composition in the study ecosystem, acting indirectly on numbers of species. Numbers of species were explained largely by ant activity, making a strong case for the MIH, but not competition. Longer periods of low rainfall may indirectly reduce species richness in desert ecosystems. However, a trend to increasing richness over time may indicate that conservation management can ameliorate this impact.

Effects of extractive use on forest birds in Western Himalayas: Role of local and landscape factors

Rural populations in developing countries depend on forests for fuelwood, fodder and other non-timber forest products. Such dependence has significant effects on faunal diversity and composition, primarily due to alteration of vegetation structure. While earlier studies have assessed the consequences of extractive activities for forest fauna, very few simultaneously acknowledge the role of landscape context, which includes agricultural land-uses and managed forests. This study was carried out in oak-dominated forests located in the middle elevations of the Western Himalayas to investigate effects of extractive activities on avifaunal communities, taking into account the role of landscape composition. Birds were sampled at 74 sites, six times each, over two seasons using fixed-radius point counts. We analysed avian species richness, abundance, composition and guild abundances (based on foraging and habitat preference) as a function of vegetation structure and proportion of dense oak forest around each site. Our results suggest that extractive activities in forests can result in reduced species richness, abundance and altered composition of forest avifauna, brought about by changes in vegetation structure. We also find that these effects may be intensified by the loss of dense oak forests in the landscape. Insectivorous birds and forest specialists were most sensitive to extractive activities and landscape composition. Decreasing canopy cover and proportion of oak forest in the landscape had strong negative effects on insectivorous and forest specialist species. Other local factors such as vertical stratification and understory density also had effects on these avian guilds. Our study indicates that in order to conserve bird species in an increasingly human-dominated landscape of the Western Himalayas, it may be necessary to control extractive activities that affect forest structure as well as retain protected forest stands within a continuum of harvested forest and agricultural landscapes.

Diversity loss in grasslands due to the increasing dominance of alien and native competitive herbs

The increasing dominance of competitive plant species may reduce species richness of plant communities. Yet, species richness may depend on spatial scale and the alien versus native status of the dominant species. To explore the dominance effects of alien versus native species on species richness, we sampled semi-natural grasslands in southwestern Poland. We established 100 m2 squares at different grassland sites, and in two opposite corners we placed two series of five nested plots (0.001, 0.01, 0.1, 1 and 10 m2), in which we recorded all vascular plant species. Next, we selected squares with a strongly dominant plant in one corner (high-dominance series) and with no strong dominant in the opposite corner (low-dominance series). The number of species per plot and the slopes of the species–area curves fitted to each nested-plot series were used to assess whether the alien vs. native status of the dominant species influences species-richness pattern across scales. We found a significantly lower number of species in the high-dominance series than in the low-dominance series, regardless of the alien versus native status of the dominant species. The slopes of the species–area curves indicated that the rate of species accumulation with increasing area was faster in the high-dominance series than in the low-dominance series; however, this pattern did not depend on the alien vs. native status of the dominants. Our study confirms that increasing dominance is linked to a decline in species richness, but reveals that alien dominants do not have a stronger impact than native dominants.

Temperature and surface runoff affect the community of periphytic diatoms and have distinct effects on functional groups: evidence of a mesocosms experiment

In response to climate change it is expected an increase in temperature and precipitation in subtropical regions of South America. Precipitation increases surface runoff, which leads to an increased input of nutrients and suspended solids in freshwater ecosystems, resulting in changes in turbidity and water color. We analyzed the effects of increased temperature and surface runoff (simulated by soil addition) on freshwater periphytic diatom communities through a bi-factorial (temperature: ambient and increased in 2.5°C; runoff: present and absent) experiment, simulating lentic waters in mesocosms of polyethylene. Diatom species richness was reduced by increased temperature. Further, runoff reduced species richness of high-profile and motile diatoms, while the interaction between temperature and runoff explained differences in relative abundances of the high-profile and planktonic (occurring occasionally entangled in the periphyton matrix) functional groups. The low-profile group was positively affected by soil addition. Temperature and runoff also affected the composition of all functional groups (low-profile, high-profile, motile, and planktonic diatoms). These results indicated different responses of diatom functional groups to temperature increase and surface runoff, showing the importance of considering ecological differences among functional groups to evaluate the possible consequences of climate change.

The influence of landscape alterations on changes in ground beetle (Carabidae) and spider (Araneae) functional groups between 1995 and 2013 in an urban fringe of China

Urbanization is one of the main causes of land use change, especially from 1990 to now in China, but knowledge of its effect on different functional groups of carabids and spiders in the adjacent rural areas over time remains limited. We assessed whether landscape alterations (1993 versus 2013) drove changes in carabid and spider functional groups (1995 versus 2013) in an agricultural landscape located on the fringe of a rapidly growing city in China. Although built-up land increased from 6.3% to 32% across the whole landscape, the overall species richness of carabids and spiders did not decline. In contrast to the reduction in species richness of large carabids, the species richness of small carabids increased. Species richness of both large and small spiders increased. The species composition of carabids and spiders significantly changed between 1995 and 2013. Species compositions of large, predatory carabids and large or ground-hunting spiders were more sensitive to the changes in built-up land than those of small, omnivorous carabids and small or web-building spiders. The amount of grassland (abandoned land covered by wild grass) also increased as farmers began to work in the city. The increased grassland significantly contributed to the increased species richness of predatory and macropterous carabids. However, increased landscape diversity did not affect species richness of either carabids or spiders. High landscape diversity was related to reduction in field size, resulting in a decrease in the mean body size of carabids. This indicates that evaluating the effect of landscape change on carabid and spider diversity should be based on their functional traits. Different taxa, even different functional groups, have different responses to landscape change. The increase in built-up land did not immediately reduce species richness at the urban fringe. Increasing wild grasslands and combining smaller fields may benefit farmland biodiversity in this region.

No lines in the sand: Impacts of intense mechanized maintenance regimes on sandy beach ecosystems span the intertidal zone on urban coasts

Abstract As coastal population growth accelerates, intensive management practices increasingly alter urban shorelines, creating major conservation challenges. To evaluate key ecological impacts and identify indicators of coastal urbanization, we compared intertidal macroinvertebrate communities between urban beaches with intense maintenance regimes (sediment filling and grooming) and reference beaches lacking such maintenance in densely populated southern California. On urban beaches, intertidal communities were highly impacted with significantly reduced species richness, abundance, and biomass (effect sizes: 79%, 49%, 30%, respectively). Urban impacts affected macroinvertebrates across all intertidal zones, with greatest effects on upper intertidal wrack-associated taxa. On urban beaches altered intertidal communities were remarkably homogeneous across littoral cells in a biogeographically complex region. Functional diversity comparisons suggested degraded ecological functioning on urban beaches. No taxa flourished on urban beaches, but we identified several vulnerable indicator taxa. Our results suggest intense maintenance regimes on urban coasts are negatively impacting sandy beach ecosystems on a landscape scale. Beaches not subject to intense mechanized maintenance, can support high biodiversity, even near major urban centers.

Roles of Chinese Medicine and Gut Microbiota in Chronic Constipation.

Chronic constipation is a common gastrointestinal dysfunction, but its aetiology and pathogenesis are still unclear. Interestingly, the compositions of the gut microbiota in constipation patients and healthy controls are different. Various studies reported the different gut microbiota alterations in constipation patients, but most studies indicated that constipation patients showed the decreased beneficial bacteria and the reduced species richness of gut bacteria. Besides, the alterations in the gut microbiota may lead to constipation and constipation-related symptoms and the regulation of gut microbiota has a positive effect on gut functional diseases such as constipation. Microbial treatment methods, such as probiotics, prebiotics, synbiotics, and fecal microbiota transplantation, can be used to regulate gut microbiota. Increasing evidences have suggested that Chinese medicine (CM) has a good therapeutic effect on chronic constipation. Chinese medicine is well known for its multitarget and multimode effects on diseases as well as less side effects. In previous studies, after the treatment of constipation with CM, the gut microbiota was restored, indicating that the gut microbiota might be the target or important way for CM to exert its efficacy. In this review, we summarized the effects of microbial treatment and CM on the gut microbiota of constipation patients and discussed the relationship between CM and gut microbiota.

Selection, Succession, and Stabilization of Soil Microbial Consortia.

Soil microorganisms play fundamental roles in cycling of soil carbon, nitrogen, and other nutrients, yet we have a poor understanding of how soil microbiomes are shaped by their nutritional and physical environment. In this study, we investigated the successional dynamics of a soil microbiome during 21 weeks of enrichment on chitin and its monomer, N-acetylglucosamine. We examined succession of the soil communities in a physically heterogeneous soil matrix as well as a homogeneous liquid medium. The guiding hypothesis was that the initial species richness would influence the tendency for the selected consortia to stabilize and maintain a relatively constant community structure over time. We also hypothesized that long-term, substrate-driven growth would result in consortia with reduced species richness compared to the parent microbiome and that this process would be deterministic with relatively little variation between replicates. We found that the initial species richness does influence the long-term community stability in both liquid media and soil and that lower initial richness results in a more rapid convergence to stability. Despite use of the same soil inoculum and access to the same major substrate, the resulting community composition differed greatly in soil from that in liquid medium. Hence, distinct selective pressures in soils relative to homogenous liquid media exist and can control community succession dynamics. This difference is likely related to the fact that soil microbiomes are more likely to thrive, with fewer compositional changes, in a soil matrix than in liquid environments. IMPORTANCE The soil microbiome carries out important ecosystem functions, but interactions between soil microbial communities have been difficult to study due to the high microbial diversity and complexity of the soil habitat. In this study, we successfully obtained stable consortia with reduced complexity that contained species found in the original source soil. These consortia and the methods used to obtain them can be a valuable resource for exploration of specific mechanisms underlying soil microbial community ecology. The results of this study also provide new experimental context to better inform how soil microbial communities are shaped by new environments and how a combination of initial taxonomic structure and physical environment influences stability.

Nitrogen addition reduced ecosystem stability regardless of its impacts on plant diversity

Abstract Global environmental changes are altering ecosystem stability, sometimes by altering biodiversity. For example, by driving grassland plant species loss, nitrogen (N) addition can reduce ecosystem stability. In other cases, however, N addition may alter productivity and ecosystem stability, by increasing the dominance of particularly productive or stable species. We examined how N addition affected plant diversity, productivity and the temporal stability of productivity in an 8‐year grassland experiment. We found that N addition enhanced productivity and decreased ecosystem stability throughout the experimental period, even though it reduced species richness in the first 4 years, but increased richness during the subsequent years. During the early years, N addition decreased ecosystem stability by synchronizing species fluctuations and population stability of the dominant species. During later years, N addition did not increase stability, even though it increased species richness; instead, N addition continued to decrease ecosystem stability by decreasing species dominance and stability of the dominant species, without changing the identity of the dominant species. Synthesis. Our results indicate that N addition decreased ecosystem stability via mechanisms that were both dependent and independent of plant diversity, and that the mechanisms involved shifted over time. N addition impacted on ecosystem functioning through species richness and the effects on species dominance and the stability of most dominant species, highlighting the join effect of multiple biotic drivers in regulating ecosystem stability.

SUN-092 Distinct Changes in Gut Microbiota Are Associated with Estradiol-Mediated Protection from Diet-Induced Obesity in Female Mice

Due to an aging-associated decrease in ovarian estrogens, postmenopausal women tend to gain weight, which predisposes them to developing cardiovascular disease, type 2 diabetes, chronic inflammation, and cancer. Estradiol replacement has been shown to protect postmenopausal women and ovariectomized rodents from obesity and metabolic disorders, but the underlying mechanisms are not fully understood. In addition to estrogens, gut microbiota are also known to regulate energy homeostasis. In this study, we investigated the effects of estrogens on gut microbiota and energy metabolism in female mice on standard diet (SD) or high-fat diet (HFD). Ovariectomized adult C57BL6/J mice received implants containing estradiol (E2) or vehicle (Veh) (n=6/group). Mice were fed SD for the first two weeks and then switched to HFD for the remaining four weeks of the study. To investigate the effects of E2 and diet on gut microbiota, fresh fecal samples were collected at various times during SD and HFD for 16S rRNA gene sequencing. Using metabolic cages, the effects of E2 and HFD on energy balance were assessed longitudinally by measuring food intake, energy expenditure, and physical activity. In addition, plasma glucose, insulin, leptin, resistin and cytokines were measured during SD and HFD. Insulin sensitivity and glucose metabolism were assessed during a 2-hr hyperinsulinemic-euglycemic clamp in awake mice at the end of HFD. Our results indicate that chronic E2 treatment protected the ovariectomized mice from HFD-induced obesity, mostly due to increases in energy expenditure and physical activity. These effects were associated with altered bacterial communities; E2 increased the relative abundance of the mucin-producing microbes Akkermansia spp. (phylum Verrucomicrobia) that are responsible for the integrity of the gut epithelial barrier. Veh mice had increased the relative abundances of Erysipleotrichaceae and Streptococcaceae (family) and their lower taxa. HFD profoundly altered microbial diversity by reducing species richness, increasing evenness and altering relative abundances of multiple taxa. HFD was associated with increased Bacteriodes (phylum Bacteriodetes) and Clostridia (phylum Firmicutes), which are responsible for HFD-induced weight gain in humans. The relative abundance of Erysipleotrichi was positively correlated with HFD, but negatively correlated with E2 treatment, suggesting a potential causal relationship between this taxon and obesity. E2-treated mice were more insulin-sensitive with marked increases in whole body glucose turnover and glycogen synthesis after HFD. Taken together, these results suggest that changes in gut microbiota contribute to E2-mediated protection against diet-induced obesity and metabolic dysregulation. These findings may provide important insights for potential microbial targets for the treatment of metabolic disorders in women.

Tropical logging and deforestation impacts multiple scales of weevil beta-diversity

Half of Borneo's forest has been logged and oil palm plantations have replaced millions of hectares of forest since the 1970's. While this extensive land-use change has been shown to reduce species richness across landscapes, there is limited current knowledge on how deforestation affects the spatial arrangement of ecological communities. Identifying responses of beta-diversity to land-use change may reveal processes which could mitigate total biodiversity loss. We sampled weevils (superfamily: Curculionoidea) at multiple spatial scales across a land-use gradient at the Stability of Altered Forest Ecosystems (SAFE) Project in Sabah, Malaysia, in 2011–2012. We caught 160 taxa of weevil and calculated the response of alpha-diversity (1-ha scale) and beta-diversity (10-, 100-, and 1000-ha scales) to disturbance. Alpha-diversity of weevils was greatest in unlogged forest but landscape-level beta-diversity (100- and 1000-ha scale) was maintained across logged and unlogged due to high rates of spatial turnover. Turnover at smallest spatial scales (10-ha) in unlogged forest was highest in rough, flat terrain but smooth, sloping terrain had highest turnover in logged forest. Logging of flat terrain at small spatial scales has potential to decrease beta-diversity at greater scales. Beta-diversity at landscape-level in oil palm plantation remained high but was propagated by abundance shifts of few species instead of spatial turnover of many species. High temporal beta-diversity in unlogged forest was evident through periodic fluxes in abundance of many weevil species. We conclude that unlogged forest is irreplaceable for high beetle biodiversity but increased spatial turnover in some terrains may help conserve beetle communities in heavily-degraded landscapes.

Positive effects of the tea catechin (-)-epigallocatechin-3-gallate on gut bacteria and fitness of Ectropis obliqua Prout (Lepidoptera: Geometridae)

Ectropis obliqua Prout (Lepidoptera: Geometridae) is the most devastating insect pest of tea plants in China and infests thousands of hectares of tea plantations in China annually. (-)-Epigallocatechin-3-gallate (EGCG) is a major phenolic compound in tea leaves and has a strong antibacterial function. Here, we show that EGCG can effectively improve the fitness of E. obliqua larvae and present the reason by which EGCG promotes larval fitness. In this study, we compared the fitness difference among Control, Antibiotic and Treatment of larvae. The fitness of larvae treated with EGCG and antibiotic was similar and better than that of control group. We also demonstrated that EGCG treatment could significantly reduce species richness and abundance of gut bacteria in E. obliqua larvae. Hence that we speculate that EGCG promotes larval fitness and is associated with ECGG antimicrobial activity. In short, our study provides evidence of the E. obliqua larvae have adapted to secondary compounds found in tea leaves, and may even benefit from these compounds. Our study also contributes to a greater understanding of the reason involved in plant–insect interactions.

TRACING ORIGIN AND COLLAPSE OF HOLOCENE BENTHIC BASELINE COMMUNITIES IN THE NORTHERN ADRIATIC SEA

The shallow northern Adriatic Sea has a long history of anthropogenic impacts that reaches back many centuries. While the effects of eutrophication, overfishing, pollution, and trawling over recent decades have been extensively studied, the major ecological turnovers during the Holocene as a whole remain poorly explored. In this study, we reconstruct ecological baselines defining benthic ecosystem composition prior to major anthropogenic changes at four stations characterized by low sedimentation and millennial-scale time averaging of molluscan assemblages. We discriminate between natural and anthropogenic drivers based on (1) stratigraphic changes in the composition of molluscan communities observed in sediment cores and (2) changes in concentrations of heavy metals, pollutants, and organic enrichment. The four 1.5-m long sediment cores reach back to the Pleistocene–Holocene boundary, allowing for a stratigraphic distinction of the major sea-level phases of the Holocene. During the transgressive phase and maximum flooding, sea-level and establishment of the modern circulation pattern determined the development of benthic communities in shallow-water, vegetated habitats with epifaunal biostromes and, in deeper waters, with bryozoan meadows. After sea-level stabilization, the composition of these baseline communities remained relatively uniform and started to change markedly only with the intensification of human impacts in the late highstand, leading to a dominance of infauna and a decline of epifauna at all sites. This profound ecological change reduced species richness, increased the abundance of infaunal suspension feeders, and led to a decline of grazers and deposit feeders. We suggest that modern soft-bottom benthic communities in the northern Adriatic Sea today do not show the high geographic heterogeneity in composition characteristic of benthos prior to anthropogenic influences.