Effects of diet shift on the gut microbiota of the critically endangered Siberian Crane

Wetlands worldwide have suffered from serious degradation and transformation,leading to waterbirds increasingly dependent on agricultural fields for feeding.Although gut microbiota is an essential component of host health,the impacts of agricultural feeding on gut microbial community and pathogen transmission remain poorly understood.To fill this knowledge gap,we used 16S rRNA sequencing to characterize the fecal bacterial community of the Siberian Crane(Grus leucogeranus),a Critically Endangered species,that recently has shifted its foraging from largely Vallisneria tubers in Poyang Lake natural wetlands to crops(i.e.,rice seeds and lotus rhizomes) in agricultural fields.We compared the bacterial communities between tuber foraging cranes and crop foraging cranes.Our results indicate that diet shift greatly modified the gut microbiota diversity,composition and function.Crop foraging cranes had higher microbiota diversity than tuber foraging cranes.The alteration in microbiota composition and function were correlated with change in food nutrition.Tuber(i.e.,high in fiber)foraging cranes were enriched in Clostridiaceae with fiber digestion ability,and crop(i.e.,high in carbohydrate)foraging cranes were enriched in bacterial taxa and functions related to carbohydrate metabolism.The flexibility of gut microbiota might enhance Siberian Cranes’ ability to adapt to novel diet and environment.However,many enriched families in crop foraging cranes were pathogenic bacteria,which might increase the susceptibility of cranes to pathogenic infection.Special caution should be taken to agricultural feeding waterbirds in Asia,where the widespread poultry-keeping in over-harvested rice fields might increase the transmission probability of pathogenetic bacteria among wild birds,domestic poultry and humans.

A highly effective incubation strategy enhanced the urban bird hatch success

Urbanization is currently considered one of the most rapid types of global environmental change.Urban habitats are biotically and abiotically different from their rural areas,i.e.,the ambient temperature,predator,and food availability.These novel challenges create new selection pressures,which allow one to investigate ecoevolutionary responses to contemporary environmental change.A total of 118 breeding nests were monitored for nest predation in both urban and rural areas from 2018 to 2020.We used environmental factors from urban and rural areas and behavioral data from 439 Chinese Blackbird(Turdus mandarinus)valid incubation days to understand the impact of urbanization on the incubation behavior of blackbirds and its adaptation mechanism to the urban environment.Cities have warmer ambient temperatures and lower predation pressures than rural areas.Urban blackbirds chose the incubation strategy with shorter and more bouts,while rural blackbirds selected the incubation strategy with longer and fewer bouts.The plasticity of incubation behavior of urban blackbirds was higher than that of rural areas,and the range of egg temperature was also higher than that of rural areas.In addition,incubation temperature and the number of bouts per day were the key factors affecting the day survival rate of blackbirds,and the hatching rate of urban blackbirds was higher than that of rural blackbirds.Our results provide evidence for behavioral shifts in blackbirds during adaptation to urbanization and support the central role of behavioral adaptation in the successful colonization of new environments by wildlife.These help us understand the behavioral characteristics required for wildlife to live in cities and the urban adaptors faced environmental pressures.

The impact of geomorphology of marsh creeks on fish assemblage in Changjiang River estuary

Tidal marshes are an important habitat and nursery area for fi sh.In the past few decades,rapid economic development in the coastal areas of China has led to the interruption and destruction of an increasing number of tidal marshes.The growing interest in tidal marsh restoration has increased the need to understand the relationship between geomorphological features and fi sh assemblages in the design of marsh restoration projects.We studied temporal variations in,and the effects of creek geomorphological features on,the estuarine tidal creek fi sh community.Using modifi ed channel nets,we sampled fi sh monthly from March 2007 to February 2008 from seven tidal creeks along an intertidal channel system in Chongming Dongtan National Nature Reserve.Fourteen creek geomorphological variables were measured or derived to characterize intertidal creek geomorphological features.The Gobiidae,with 10 species,was the most speciesrich family.The most abundant fi sh species were Liza affi nis,Chelon haematocheilus,and Lateolabrax maculatus.The fi sh community was dominated by juvenile marine transients,which comprised about 80% of the total catch.The highest abundance of fi sh occurred in June and July,and the highest biomass occurred in December.Canonical redundancy analyses demonstrated that depth,steepness,cross-sectional area,and volume signifi cantly affected the fi sh species assemblage.L.affi nis favored small creeks with high elevations.Synechogobius ommaturus,Acanthogobius luridus,and Carassius auratus preferred deep,steep creeks with a large cross-sectional area and volume.These fi ndings indicate that the geomorphological features of tidal creeks should be considered in the conservation and sustainable management of fi sh species and in the restoration of salt marshes.

Reserve network planning for fishes in the middle and lower Yangtze River basin by systematic conservation approaches

Although China has established more than 600 wetland nature reserves, conservation gaps still exist for many species, especially for freshwater fishes. Underlying this problem is the fact that top-level planning is missing in the construction of nature reserves. To promote the development of nature reserves for fishes, this study took the middle and lower reaches of the Yangtze River basin(MLYRB) as an example to carry out top-level reserve network planning for fishes using approaches of systematic conservation planning. Typical fish species living in freshwater habitats were defined and considered in the planning. Based on sample data collected from large quantities of literatures, continuous distribution patterns of 142 fishes were obtained with species distribution modeling and subsequent processing, and the distributions of another eleven species were artificially designated. With the distribution pattern of species, Marxan was used to carry out conservation planning. To obtain ideal solutions with representativeness, persistence, and efficiency, parameters were set with careful consideration regarding existing wetland reserves, human disturbances, hydrological connectivity, and representation targets of species. Marxan produced the selection frequency of planning units(PUs) and a best solution. Selection frequency indicates the relative protection importance of a PU. The best solution is a representative of ideal fish reserve networks. Both of the PUs with high selection frequency and those in the best solution have low proportions included in existing wetland nature reserves, suggesting that there are significant conservation gaps for fish species in MLYRB. The best solution could serve as a reference for establishing a fish reserve network in the MLYRB. There is great flexibility for replacing selected PUs in the solution, and such flexibility facilitates the implementation of the solution in reality in case of unexpected obstacles. Further, we suggested adopting a freshwater management framework in the implementation of such solution.

Genetic Diversity of Crop Wild Relatives under Threat in Yangtze River Basin:Call for Enhanced In Situ Conservation and Utilization

The changing climate threatens agricultural production and food security(Vincent et al.,2019).The limited genetic diversity of crops restricts the improvement potential,which acts as an inevitable barrier for breeding new,climate-fluctuating tolerant cultivated varieties with higher yields.

Incomplete lineage sorting and introgression in the diversification of Chinese spot-billed ducks and mallards

Incomplete lineage sorting and introgression are 2 major and nonexclusive causes of specieslevel non-monophyly.Distinguishing between these 2 processes is notoriously difficult because they can generate similar genetic signatures.Previous studies have suggested that 2 closely related duck species,the Chinese spot-billed duck Anas zonorhyncha and the mallard A.platyrhynchosvjere polyphyletically intermixed.Here,we utilized a wide geographical sampling,multilocus data and a coalescent-based model to revisit this system.Our study confirms the finding that Chinese spot-billed ducks and Mallards are not monophyletic.There was no apparent interspecific differentiation across loci except those at the mitochondrial DNA(mtDNA)control region and the Z chromosome(CHD1Z).Based on an isolation-with-migration model and the geographical distribution of lineages,we suggest that both introgression and incomplete lineage sorting might contribute to the observed non-monophyly of the 2 closely related duck species.The mtDNA introgression was asymmetric,with high gene flow from Chinese spot-billed ducks to Mallards and negligible gene flow in the opposite direction.Given that the 2 duck species are phenotypically distinctive but weakly genetically differentiated,future work based on genomescale data is necessary to uncover genomic regions that are involved in divergence,and this work may provide further insights into the evolutionary histories of the 2 species and other waterfowls.

Applications of systematic approaches in freshwater conservation planning

Systematic conservation planning(SCP)is a widely accepted biodiversity-focused approach to selecting priority areas for protection.Since freshwater ecosystems are globally in urgent need of more conservation and the development of freshwater protected areas has lagged behind such need,SCP is proposed to be widely applied in freshwater conservation.As SCP originates from terrestrial realms,freshwater-specific characteristics should be considered when applied to freshwater systems.The challenges mainly include difficulty in data collection for freshwater species and uncertainty in classification of coarse-filters for representation,while also considering the maintenance of natural connectivity in fresh waters and taking longitudinal,lateral,and climate-change-caused threats into account.Only by addressing these issues may the representativeness and persistence of freshwater biodiversity be ensured in the proposed conservation network.Though challenging at times,the application of systematic approaches in freshwater conservation planning has been widely attempted throughout the last 12 years and applied in different freshwater ecosystems at different scales.In addition,the consideration of freshwater-specific issues has been becoming more and more comprehensive.This review divides the whole process of SCP into successive steps while discussing detailed applications of freshwater planning at each step.First,according to the review,each step attempts to explore many alternatives,such as usingsurrogates from the species level to the ecosystem level(or a combination within this range)to represent the spatial variation of freshwater biodiversity,deriving raw data from various sources to use for planning,applying different techniques to expand or integrate data,setting various target forms to ensure representativeness or persistence,considering existing protected areas in different ways in the process of planning,using priority principles in various paradigms for both representativeness and persistence,and applying several types of software to the final design of the protection network.Second,applications in each step(except‘‘setting representative targets’’)have been more or less tried in considering freshwater-specific issues.For representativeness issues,accepting various sources of information and attempting different ways of data reduction are the main approaches to solving these challenges.For persistence issues,identifying the main ecological processes and threats in freshwater systems and involving them in the process of prioritization are major concerns,and setting targets or priority principles are key steps for taking these persistence issues into account.Finally,more systematic conservation of freshwater systems and new or improved alternatives of each step are expected to enrich this field of study.

Testing mechanisms underlying elevational patterns of lakeshore plant community assembly in Poyang Lake, China

Aims Plant community assembly in wetlands usually changes with eleva-tion gradients,which may be due to the direct effect of flooding and indirect effects such as changes in soil properties and competition.However,the respective importance of each factor remains to be investigated.Methods We investigated patterns of plant diversity,community biomass and soil properties along an elevation gradient of a lakeshore meadow at Poyang Lake,China.Important Findings(i)With increasing elevation,species richness and Simpson diver-sity index decreased.Both aboveground biomass(AGB)and below-ground biomass(BGB)increased with elevation,however,the BGB/AGB ratio also increased,which suggests a significant effect of belowground competition.(ii)Soil N content and soil N:P ratio increased,whereas soil pH decreased with elevation.Other soil properties showed no significant response.(iii)Structural equa-tion modeling showed that variation of plant diversity was mainly explained by BGB.Thus,intensified belowground competition seems to be the primary mechanism causing lower plant diversity at higher elevations.(iv)These findings were further supported by the observed greater response ratio of N and P storage in plant commu-nities than the response ratio of soil N and P content to elevation,suggesting that soil nutrient limitation and belowground nutrient competition increased with elevation.Our study has important implications to wetland management and biodiversity conserva-tion under environmental change(e.g.changes in flooding regimes,eutrophication).