The gut microbiota of migratory waterbirds is affected by various complex factors,including cross-species transmission,which increases the risk of pathogen spreading among sympatric animals and poses a potential publi...The gut microbiota of migratory waterbirds is affected by various complex factors,including cross-species transmission,which increases the risk of pathogen spreading among sympatric animals and poses a potential public health risk to humans.In this study,we investigated the microbial communities of wintering Bean Geese(Anser fabalis),Domestic Ducks(A.platyrhynchos domesticus),humans,and soil using high-throughput sequencing of the 16S rRNA gene region in Shengjin Lake,China.In total,6,046,677 clean reads were obtained,representing 41,119 operational taxonomic units(OTUs)across the four groups.The dominant microbial phyla were the Proteobacteria,Firmicutes,Bacteroidota,and Actinobacteriota.The Sorensen similarity index and alpha and beta diversity results showed that the gut microbial communities of Bean Geese and Domestic Ducks were more similar to those of the other pairs.Network analysis revealed that Faecalibacterium prausnitzii,Pseudomonas fragi,and Bradyrhizobium elkanii were hubs of the three major modules.Fourteen common microbiomes were iden-tified in Bean Geese,Domestic Ducks,humans,and soil in Shengjin Lake.A total of 96 potential pathogens were identified among the four groups,with 20 specific potentially pathogenic microbiomes found in the gut of Bean Geese.Some of these pathogens are responsible for significant financial losses in the poultry industry and pose risks to human health.Klebsiella pneumoniae,Morganella morganii,Escherichia coli,and Ralstonia insidiosa are potential core pathogens found in the four groups at Shengjin Lake that can cause diseases in humans and an-imals and facilitate cross-species transmission through various media.Therefore,humans are at risk of con-tracting these pathogens from migratory birds because of their frequent contact with domestic poultry.However,further studies are required to explore the potential pathogenic species and transmission pathways among sympatric wintering Bean Geese,Domestic Ducks,humans,and soil.展开更多
Background:The reliability of long-term population estimates is crucial for conservation and management purposes.Most previous studies assume that count indices are proportionally related to abundance;however,this ass...Background:The reliability of long-term population estimates is crucial for conservation and management purposes.Most previous studies assume that count indices are proportionally related to abundance;however,this assumption may not hold when detection varies spatially and temporally.We examined seasonal variations in abundance of three bird species(Cabot’s Tragopan Tragopan caboti,Silver Pheasant Lophura nycthemera,and Whitenecklaced Partridge Arborophila gingica) along an elevational gradient,using N-mixture models that take into account imperfect detection in our bird data.Methods:Camera-trapping was used to monitor temporal activity patterns of these species at Guangdong Nanling National Nature Reserve from December 2013 to November 2017(4 seasons per year).For abundance analysis(N-mixture modeling),we divided a year into 4 seasons,i.e.3 months per season,and performed the analysis by season.Elevation was incorporated into the N-mixture model as a covariate that may affect abundance.We compared the N-mixture model with a null model(no covariate model) and selected the better model based on AIC values to make an inference.Results:From 24 sampling sites,we obtained 6786 photographs of 8482 individuals of 44 bird species and 26 mammal species.Silver Pheasant was photographed much more frequently and showed higher temporal activity frequency than White-necklaced Partridge or Cabot’s Tragopan.Silver Pheasant was camera-captured most frequently in summer,and other two species in winters.All three species had two daytime activity peaks:between 6:00 a.m.and 10:00 a.m.,and between 5:00 p.m.and 7:00 p.m.,respectively.Our estimated abundance and detection probability from the N-mixture model were variable by season.In particular,all three species showed greater abundance in summer than in winter,and estimated abundance patterns of all three species were more similar with observed cameratrapping counts in summers.Moreover,in winter,elevation had a positive impact on abundance of Silver Pheasant and Cabot’s Tragopan,but not on White-necklaced Partridge.Conclusions:Our results demonstrate that the N-mixture model performed well in the estimation of temporal popu lation abundance at local fixed permanent plots in mountain habitat in southern China,based on the modeling of repeated camera-trapping counts.The seasonal differences in abundance of the three endemic bird species and the strong effect of elevation on abundance of two species in winter were only indicative of variations in spatio-tempora distribution within species and between species.In identifying suitable habitat for endemic pheasants,the positive elevational effect also suggests that more attention should be paid to conservation of areas with higher elevation in the Nanling Mountains.展开更多
Sympatric reptiles are the ideal system for investigating temperature-driven coexistence. Understanding thermally physiological responses of sympatric lizards is necessary to reveal the physiological mechanisms that u...Sympatric reptiles are the ideal system for investigating temperature-driven coexistence. Understanding thermally physiological responses of sympatric lizards is necessary to reveal the physiological mechanisms that underpin the sympatric occurrence of reptiles. In this study, we used three lizard species, Eremias argus, E. multiocellata, and Phrynocephalus przewalskii, which are sympatric in the Inner Mongolia desert steppe, as a study system. By comparing their resting metabolic rates(RMR) and locomotion at different body temperatures, we aimed to better understand their physiological responses to thermal environments, which may explain the sympatric occurrence of these lizards. Our results showed that E. argus had significantly higher RMR and sprint speed than E. multiocellata, and higher RMR than P. przewalskii. In addition, the optimal temperature that maximized metabolic rates and locomotion for E. argus and E. multiocellata was 36°C, whereas for P. przewalskii it was 39°C. Our study revealed the physiological responses to temperatures that justify the sympatric occurrence of these lizards with different thermal and microhabitat preferences and active body temperatures. Eremias argus and E. multiocellata, which have lower body temperatures than P. przewalskii, depend on higher RMR and locomotion to compensate for their lower body temperatures in field conditions. Our study also highlights the importance of using an integrative approach, combining behavior and physiology, to explore the basis of sympatric occurrence in ectothermic species.展开更多
Gut microbiota and host interactions co-evolve and develop into stably adapted microbial communities and play vital roles in maintaining the health of organisms.Diet is supposed to be an important driver of difference...Gut microbiota and host interactions co-evolve and develop into stably adapted microbial communities and play vital roles in maintaining the health of organisms.Diet is supposed to be an important driver of differences in gut microbiota,but previous studies would commonly use literature depictions,which are essential but inaccurate,to explain the effects of diet on the gut microbiota of wild birds.In this study,we collected intestinal samples from five sympatric flycatchers to compare the gut microbial differences using bacterial 16S rRNA genes from Illumina MiSeq platform.Over 1,642,482 quality-filtered sequences from 1816S rRNA libraries were obtained and distinct compositions and diversities of gut microbiota were found in five flycatchers.Their gut microbiota is mainly from the four bacterial phyla of Proteobacteria,Firmicutes,Actinomycetes,and Bacteroidetes,but at the genus level showed a significant difference.Functional predictions revealed that the metabolic capacity of the gut microbiota of five flycatchers is greatly distinguished at KEGG level 3.And multiple food fragments showed a significant correlation with gut microbiota.Besides,the significant differences in the specific composition of the diets of the five insectivorous flycatchers indicated the differentiation of dietary niches.The study of the gut microbiota and feeding habits of sympatric flycatchers would increase the understanding of the gut microbial diversity of wild birds,and also improve our cognition of the co-evolution and co-adaptation within the host gut microbiota relations.展开更多
An individual-based model, EcoSim, was employed to investigate if specialized resource use could promote sympatric speciation. Prey individuals in the original version of EcoSim were supplied with a single primary foo...An individual-based model, EcoSim, was employed to investigate if specialized resource use could promote sympatric speciation. Prey individuals in the original version of EcoSim were supplied with a single primary food resource. A dual resource version with different food resources (Food 1 and Food 2) was also developed to create favorable conditions for the emergence of specialized food consumption among prey individuals. The single resource version was used as the control to determine the impact of the presence of multiple food resources on the occurrence of sympatric speciation. Each unit of Food 2 contained a higher amount of energy than Food 1, and Food 1 was more accessible than Food 2. Initially, prey individuals mostly fed on Food 1. How-ever, after the emergence of food specialization, the consumption rate of Food 2 signifi-cantly exceeded the consumption rate of Food 1;although prey individuals more frequently encountered Food 1. While sympatric speciation was observed in the dual resource version runs, we could not identify any sympatric species in the single resource version runs. Machine learning techniques were also employed to identify the most influential initial conditions leading to sympatric speciation. According to the obtained results, in most lineages sympatric speciation occurred at the beginning of the food specialization pro-cess. When the lineage had a high special diversity, the lineage needed two different criteria to diverge sympatrically: possessing high genetic diversity and a large population size. In support of previous findings, this study demonstrated that the most accurate determination of initial conditions leading to sympatric speciation can be obtained from lineages that are at the beginning of the divergence process. In conclusion, this study indicated that divergent foraging behavior could potentially lead to the sympatric emergence of new species in the absence of geographic isolation.展开更多
The efficacy of nest-site choice ultimately determines the breeding success of birds. Comparisons of the reproductive strategies of various bird species which inhabit the same habitat may provide insights on the evolu...The efficacy of nest-site choice ultimately determines the breeding success of birds. Comparisons of the reproductive strategies of various bird species which inhabit the same habitat may provide insights on the evolution of the diverse life-history strategies in birds. In this study, nest-site choice and breeding success of four species of passerine birds that rely on reeds for reproduction were investigated in a wetland in Hebei, China. The four species were the Oriental reed warbler(Acrocephalus orientalis)(ORW), the blunt-winged warbler(Acrocephalus concinens)(BW), the reed parrotbill(Paradoxornis heudei)(RP), and the vinous-throated parrotbill(Sinosuthora webbiana)(VP). Our results showed that breeding nests of the four species were distributed in a mosaic pattern within the same habitat, with similar nest shapes/structures and nest-sites in the reeds. The only characteristics which differed significantly among the species were nest height above the water surface, height of reeds where nests were placed, and density of reeds around the nest site. In addition, the starting time of reproduction clearly differed for the four species. The breeding success rates of the four species were 34.5%(86/249) for ORW, 35.3%(6/17) for BW, 38.5%(15/39) for RP, and 40.9%(9/22) for VP in the two study years. The main factors affecting the breeding success were nest predation and poor weather conditions, like heavy rainstorms and wind, while nest parasitism by the common cuckoo(Cuculus canorus) represented an important factor for breeding failure only in the Oriental reed warbler. Our study demonstrated that these four sympatric species of passerine birds inhabiting the same wetland exhibit differences in terms of nest-site choice and breeding phenology.展开更多
Electroantennogram (EAG) responses of male and female Oedipodinae grasshop-pers, Oedaleus decorus asiaticus B.-Bienko and Angaracris barabensis Pall to 37 plant volatile compounds were recorded. The two species have s...Electroantennogram (EAG) responses of male and female Oedipodinae grasshop-pers, Oedaleus decorus asiaticus B.-Bienko and Angaracris barabensis Pall to 37 plant volatile compounds were recorded. The two species have sympatric distribution and synchronous sea-sonal activity in Inner Mongolia Grasslands. They have different host plant preference with Oedaleus decorus asiaticus graminivorous and A. barabensis forbivorous. The EAG response profiles to 37 compounds of the two species and their both sexes were similar. Most of the green leaf volatiles elicited higher EAG responses in both species and sexes than terpenic compounds and some aromatic compounds. Strong EAG responses were elicited by 6-carbon alcohols (1-hexanol, Z-hexen-2-ol-1, E-2-hexen-1-ol, E-hexen-3-ol-1), aldehyde (E-2-hexen-1-al), ester (Z-hexen-3-yl acetate), and 7-carbon alcohols (1-heptanol) in both species and sexes. Monoterpenes with functional groups of alcohols and aldehydes were more stimulating than other monoterpenes tested. The sesquiterpenes tested elicited relatively low responses. Ben-zaldehyde elicited the highest responses for both species among aromatic components. Oedaleus decorus asiaticus showed higher EAG responses than A. barabensis to the green leaf volatiles, 1-decanol, 1-nonanol, 1-pentanol, hexanal, Z-hexen-3-yl acetate and to the sesquiter-penes (-)-trans-caryophyllene. Males have higher responses than females in Oedaleus decorus asiaticus. No sexual difference was observed in A. barabensis. Dose-dependent responses to six selected chemicals were observed from females. In both species, all the chemicals tested elicit EAG responses at concentration between 10-3 mol/L and 10-2 mol/L, except that the responses of A. barabensis to terpineol had a threshold concentration of 10-2 mol/L benzaldehyde and 1-hexanol had the highest slopes in dose curves, while 1-octen-3-ol showed the smallest slope in responses to the six chemicals tested. Comparative studies on the responses of two antennal sections and the whole antenna to six selected chemicals were carried out using females of both species. A significant EAG response was only recorded from the distal part of the antenna and not from the proximal seven segments.展开更多
Effects of elevated CO2 （twice ambient vs. ambient） and Bt CrylAc transgene （Bt cotton cv. 33B vs. its nontransgenic parental line cv. DP5415） on the interspecific competition between two ecologically similar spec...Effects of elevated CO2 （twice ambient vs. ambient） and Bt CrylAc transgene （Bt cotton cv. 33B vs. its nontransgenic parental line cv. DP5415） on the interspecific competition between two ecologically similar species of cotton aphid Aphis gossypii and whitefly biotype-Q Bemisia tabaci were studied in open-top chambers. The results indicated that elevated CO2 and Bt cotton both affected the population abundances of A. gossypii and biotype-Q B. tabaci when introduced solely （i.e., without interspecific competition） or two species coexisted （i.e., with interspecific competition）. Compared with ambient CO2, elevated COe increased the population abundances ofA. gossypii and biotype-Q B. tabaci as fed on Bt and nontransgenic cotton on 45 （i.e., seedling stage） and 60 （i.e., flowering stage） days after planting （DAP）, but only significantly enhanced aphid abundance without interspecific competition on the 45-DAP nontransgenic cotton and 60-DAP Bt cotton, and significantly increased whitefly abundance with interspecific competition on the 45-DAP Bt cotton and 60-DAP nontransgenic cotton. In addition, compared with nontransgenic cotton at elevated CO2, Bt cotton significantly reduced biotype-Q B. tabaci abundances without and with interspecific competition during seedling and flowering stage, while only significantly decreasing A. gossypii abundances without interspecific competition during the seedling stage. When the two insect species coexisted, the proportions ofbiotype-Q B. tabaci were significantly higher than those ofA. gossypii on Bt and nontransgenic cotton at the same CO2 levels, and elevated CO2 only significantly increased the percentages of biotype-Q B. tabaci and significantly reduced the proportions of A. gossypii on seedling and flowering nontransgenic cotton. Therefore, the effects of elevated CO2 were favorable for biotype-Q B. tabaci to out-compete A. gossypii under the predicted global climate change.展开更多
Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependen...Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependent framework in species habitat relationships may lead to biased inferences.Multi-scale species distribution models(SDMs)can thus improve the predictive ability as compared to single-scale approaches.This study outlines the importance of multi-scale modeling in assessing the species habitat relationships and may provide a methodological framework using a robust algorithm to model and predict habitat suitability maps(HSMs)for similar multi-species and multi-scale studies.Results:We used a supervised machine learning algorithm,random forest(RF),to assess the habitat relationships of Asiatic wildcat(Felis lybica ornata),jungle cat(Felis chaus),Indian fox(Vulpes bengalensis),and golden-jackal(Canis aureus)at ten spatial scales(500-5000 m)in human-dominated landscapes.We calculated out-of-bag(OOB)error rates of each predictor variable across ten scales to select the most influential spatial scale variables.The scale optimization(OOB rates)indicated that model performance was associated with variables at multiple spatial scales.The species occurrence tended to be related strongest to predictor variables at broader scales(5000 m).Multivariate RF models indicated landscape composition to be strong predictors of the Asiatic wildcat,jungle cat,and Indian fox occurrences.At the same time,topographic and climatic variables were the most important predictors determining the golden jackal distribution.Our models predicted range expansion in all four species under future climatic scenarios.Conclusions:Our results highlight the importance of using multiscale distribution models when predicting the distribution and species habitat relationships.The wide adaptability of meso-carnivores allows them to persist in human-dominated regions and may even thrive in disturbed habitats.These meso-carnivores are among the few species that may benefit from climate change.展开更多
The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across ma...The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across many taxa, reproductive isolating barriers among multiple species （：〉2） that would represent the most common phenomenon in nature, remain to be clarified. Here, we use double digest restriction-site associated DNA （ddRAD） sequencing to examine patterns of hybridization at a sympatric site where three Ligularia species grow together and verify whether those patterns contribute to the maintenance of boundaries among species. The results based on the RAD SNP datasets indicated hybridization Ligularia cyathiceps x L. duciformis and L. duciformis x L. yunnanensis were both restricted toFls plus a few first-generation backcrosses and no gene introgression were identified, giving rise to strong reproductive isolation among hybridizing species. More- over, hybrid swarm simulation, using HYBRIDLAB, indicated the RAD SNP datasets had sufficient discriminatory power for accurate hybrid detection. We conclude that parental species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligualria in the eastern Qinghai-Tibetan Plateau and adjacent areas. Moreover, this study highlights the effectiveness of RAD sequencing in hybridization studies.展开更多
A new species of the Asian leaf litter toad genus Leptobrachella is described from Sichuan Province, China. Molecular phylogenetic analyses based on mitochondrial and nuclear gene sequences clustered the new species a...A new species of the Asian leaf litter toad genus Leptobrachella is described from Sichuan Province, China. Molecular phylogenetic analyses based on mitochondrial and nuclear gene sequences clustered the new species as an independent clade nested into L. oshanensis species group. The new species could be distinguished from its congeners by a combination of following characters: body size moderate(25.8–32.6 mm in male, 33.7–34.1 mm in female);distinct black spots present on flanks;toes rudimentary webbed, with narrow lateral fringes, dermal ridges under toes interrupted at articulations;ventral belly cream white with variable brown specking;skin on dorsum relatively smooth with fine tiny granules or short ridges;iris copper above, silver bellow;greyish black patches on posterior thigh absent or small;spines on surface of chest absent in male during breeding season;nasals entirely or partially separated from sphenethmoid in male;dorsal surface of tadpoles semitransparent light brown, spots on tail absent, keratodont row formula I: 3+3(2+2)/2+2: I;calls simple, call series basically consist of repeated long calls, at dominant frequency(4831.9 ± 155.8) Hz and call duration(544.5 ± 146.8) ms. In addition, we made supplementary description on L. oshanensis including holotype, variations, tadpoles, skull and bioacoustics. Besides, this paper reports cases of femoral adipose glands in the genus Leptobrachella as first known sexual dimorphism skin glands for males of Megophryidae.展开更多
Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence,differentiation in cache pilfering abilities among sympat...Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence,differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed.We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species(Tamias sibiricus,Apodemus peninsulae and Clethrionomys rufocanus)and the relationship of their pilfering abilities at the inter-and intraspecific levels.Our results showed that T.sibiricus exhibited a relatively stronger pilfering ability than A.peninsulae and C.rufocanus,as indicated by its higher recovery rate of artificial caches.Meanwhile A.peninsulae showed a medium pilfering ability and C.rufocanus displayed the lowest ability.We also noted that both cache size and cache depth significantly affected cache recovery in all three species.T.sibiricus scatter-hoarded more seeds than it larder-hoarded,A.peninsulae larder-hoarded more than scatter-hoarded,and C.rufocanus acted as a pure larder-hoarder.In T.sibiricus,individuals with lower pilfering abilities tended to scatter hoard seeds,indicating an intraspecific variation in hoarding propensity.Collectively,these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests,suggesting a strong connection between hoarding strategy and pilfering ability.展开更多
Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympa...Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed. We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species (Tamias sibiricus, Apodemus peninsulae and Clethrionomys rufocanus) and the relationship of their pilfering abilities at the inter- and intraspecific levels. Our results showed that T. sibiricus exhibited a relatively stronger pilfering ability than A. peninsulae and C. rufocanus, as indicated by its higher recovery rate of artificial caches. Meanwhile A. peninsulae showed a medium pilfering ability and C. rufocanus displayed the lowest ability. We also noted that both cache size and cache depth significantly affected cache recovery in all three species. T. sibiricus scatter-hoarded more seeds than it larder-hoarded, A. peninsulae larder-hoarded more than scatter-hoarded, and C. rufocanus acted as a pure larder-hoarder. In T. sibiricus, individuals with lower pilfering abilities tended to scatter hoard seeds, indicating an intraspecific variation in hoarding propensity. Collectively, these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests, suggesting a strong connection between hoarding strategy and pilfering ability.展开更多
Invasion of the oriental fruit lfy, Bactrocera dorsalis, into new niches containing different food sources （a process referred to as host shift）, may cause population genetic differentiation and sympatric speciation...Invasion of the oriental fruit lfy, Bactrocera dorsalis, into new niches containing different food sources （a process referred to as host shift）, may cause population genetic differentiation and sympatric speciation. To attempt to infer that experimentally, test populations were established by transferring a subset of the original populations, which had been grown on banana for many generations, onto navel orange, and then subculturing the navel orange population and banana population for at least 20 generations. Four pairs of SSR primers with high polymorphism on laboratory strains were used to detect population genetic differentiation. All six tested populations （the 5th, 10th and 15th generations of B. dorsalis fed on banana and navel orange, respectively） were found to have low genetic diversity. Furthermore, the genetic diversity of the navel orange populations was found to decline after being crossed for several generations. Populations initially were deviated from Hardy-Weinberg equilibrium, however, equilibrium was achieved with increasing numbers of generations in both of the host populations. Limited gene lfows were found among the six populations. The Nei’s standard genetic distances between the two host populations of the same generation were initially low, but increased with generation number. Genetic distances between banana and navel orange populations of the same generation were lower than genetic distances between different generations grown on the same host plant. Analysis of molecular distance （AMOVA） results based on generation groups and host groups demonstrated that genetic variation among generations was greater than that between the two host populations. The results indicated that population genetic differentiation occurred after the host shift, albeit at low level. Biogeography and taxonomy of the B. dorsalis complex revealed that speciation of B. dorsalis might be tightly associated with host shift or host specialization of B. dorsalis following dispersal.展开更多
Natural hybridization,which often occurs between closely related species exhibiting sympatric or parapatric distributions,is an important source of genetic variation within populations.The closely related Jankowski’s...Natural hybridization,which often occurs between closely related species exhibiting sympatric or parapatric distributions,is an important source of genetic variation within populations.The closely related Jankowski’s Bunting(Emberiza jankowskii)and Meadow Bunting(E.cioides)are similar in morphology and genetics,occupy overlapping niches,and are sympatric in eastern Inner Mongolia.Previous studies have reported trans-species polymorphisms of alleles between the two species,as well as an unexpectedly high genetic diversity of the endangered E.jankowskii.We speculate that introgressive hybridization has occurred between the two species and contributed to the additional unexpected variation to E.jankowskii.We used mitochondrial NADH dehydrogenase subunit 2(ND2)gene and 15 nuclear microsatellite markers to compare the genetic diversity of E.jankowskii and E.cioides,and inferred the origin of trans-species polymorphisms between the two species by phylogenetic reconstruction and Bayesian cluster analysis.The two species could be clearly distinguished by population cluster analysis.Despite the large number of mutational differences,we still detected sharing of major haplotypes and the presence of hybrids between the two species.Our study confirmed that weak introgressive hybridization has occurred between sympatric E.jankowskii and E.cioides,which may be mediated by female E.cioides individuals,and that interspecific introgression has contributed to the maintenance of high genetic diversity in E.jankowskii.While being wary of the potential negative effects of introgressive hybridization,we suggest that expanding the habitat of E.jankowskii remains the most effective conservation strategy at present.展开更多
Background:Interspecific competition is known to be strongest between those species that are both closely related and sympatric.Egrets are colonially nesting wetland birds that often overlap and can therefore be expec...Background:Interspecific competition is known to be strongest between those species that are both closely related and sympatric.Egrets are colonially nesting wetland birds that often overlap and can therefore be expected to compete in roosting and nesting habitat as well as in diet.According to the niche partitioning hypothesis,it is to be expected that these similar species would show differentiation in at least one of the main niche dimensions to reduce competition.We tested niche partitioning between the colonially nesting Little Egret(Egretta garzetta)and Cattle Egret(Bubulcus ibis)in temporal,spatial and trophic dimensions.Methods:Field study was conducted in three mixed egret colonies in Yangxian County,southwest Shaanxi Prov-ince,central China.For each nest colony we recorded its spatial location,the height of nesting trees and of nests,the height of roosting trees and of roosting individuals within the trees.We determined the first egg-laying and first hatching dates of the two species.Craw dissection of storm-killed egret nestlings was used to measure the diet.Six transects were surveyed to study foraging habitat selection.Results:We found that hatching time of Little Egrets peaked earlier(by about 1 month)than that of Cattle Egrets.Cattle Egrets nested and roosted higher than Little Egrets.The foraging habitats used by Little Egrets were dominated by river banks(73.49%),followed by paddy fields(13.25%)and reservoirs(10.84%),whereas Cattle Egret foraging sites were characterized by grasslands(44.44%),paddy fields(33.33%)and river banks(22.22%).Little Egrets consumed more fishes(65.66%)and Odonata larvae(13.69%)than Cattle Egrets,while Cattle Egrets were found feeding mainly on Coleoptera(29.69%)and Orthoptera(23.29%).Little Egrets preyed on larger mean biomasses of food items than Cattle Egrets.Conclusions:Our results confirm the niche partitioning hypothesis as a mechanism for coexistence among ecologi-cally similar species.In two coexisting egret species,niche partitioning is multidimensional,such that the two coexist-ent species occupy differing ecological space based on all three temporal,spatial and trophic niche dimensions.展开更多
Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals.However,exactly how the subordinate species coexists with superior species is unknown.In the for...Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals.However,exactly how the subordinate species coexists with superior species is unknown.In the forests west of Beijing City,intense asymmetrical interactions of food competition exist among granivorous rodents(e.g.Apodemus peninsulae,Niviventer confucianus,Sciurotamias davidianus and Tscherskia triton)that have broadly overlapping habitats and diets but have varied body size(range 15-300 g),hoarding habits(scatter vs larder)and/or daily rhythm(diurnal vs nocturnal).The smallest rodent,A.peninsulae,which typically faces high competitive pressure from larger rodents,is an ideal model to explore how subordinate species coexist with superior species.Under semi-natural enclosure conditions,we tested responses of seed-hoarding behavior in A.peninsulae to intraspecific and interspecific competitors in the situations of pre-competition(without competitor),competition(with competitor)and post-competition(competitor removed).The results showed that for A.peninsulae,the intensity of larder-hoarding increased and the intensity of scatter-hoarding declined in the presence of intraspecifics and S.davidianus,whereas A.peninsulae ceased foraging and hoarding in the presence of N.confucianus and T.triton.A.peninsulae reduced intensity of hoarding outside the nest and moved more seeds into the nest for larder-hoarding under competition from intraspecific individuals and S.davidianus.In most cases,the experimental animals could recover to their original state of pre-competition when competitors were removed.These results suggest that subordinate species contextually regulate their food-hoarding strategies according to different competitors,promoting species coexistence among sympatric animals that have asymmetrical food competition.展开更多
Reproductive isolation is a fundamental require- ment for speciation and includes several sequential stages. Few studies have determined the relative contributions of pre- and post-zygotic reproductive isolation in pl...Reproductive isolation is a fundamental require- ment for speciation and includes several sequential stages. Few studies have determined the relative contributions of pre- and post-zygotic reproductive isolation in plants, especially between relative species with clear differentiation in flower form. To investigate the mechanisms responsible for repro- ductive isolation in sympatric A4ussaenda pubescens var. alba and Mussaenda shikokiana （Rubiaceae） in Guangxi Province, China, we made observations of flowering phenology, patterns of insect visitation, and conducted pollination experiments, including artificial hybridization. The two species had over- lapping flowering times and were pollinated by overlapping pollinators; however, their relative importance differed significantly with M. pubescens visited more commonly by bees and M. shikokiana more frequently by butterflies. Using vegetative and floral characters and molecular evidence based on nuclear ribosomal internal and external transcribed spacer regions we detected seven naturally occurring hybrids among a sample of approximately 125 individuals. Hybrids were characterized by morphologies that most closely resembled their maternal parents based on chloroplast evidence. Studies of artificially synthesized and natural hybrids demonstrated that hybrid seed had very low germination rates and naturally occurring hybrids exhibited pollen sterility. Post-zygotic reproductive isolating mechanisms play a primary role in limiting gene exchange between co-occurring species and maintaining species integrity in areas of sympatry.展开更多
Sitobion avenae （E） is an important cereal pest worldwide that can survive on various plants in the Poaceae, but divergent selection on different host plants shouldpromote the evolution of specialized genotypes or h...Sitobion avenae （E） is an important cereal pest worldwide that can survive on various plants in the Poaceae, but divergent selection on different host plants shouldpromote the evolution of specialized genotypes or host races. In order to evaluate their resource use strategies, clones of S. avenae were collected from oat and barley. Host-transfer experiments for these clones were conducted in the laboratory to compare their fitness traits. Our results demonstrated that barley clones had significantly lower fecundityand tended to have longer developmental times when transferred from barley to oat. However, oat clones developed faster after they were transferred to barley. Clones fromoat and barley had diverged to a certain extent in terms of fecundity and developmental time of the nymphs. The separation of barley clones and oat clones of S. avenae was alsoevident in a principal component analysis. Barley clones tended to have higher broad-sense heritabilities for fitness traits than oat clones, indicating the genetic basis of differentiationbetween them. Barley clones showed significantly higher extent of specialization compared to oat clones from two measures of specialization （i.e., Xsp and Ysp）. Therefore, barleyclones were specialized to a certain extent, but oat clones appeared to be generalized. The fitness of S. avenae clones tended to increase with higher extent of specialization. Theevolution toward ecological specialization in S. avenae clones, as well as the underlying genetic basis, was discussed.展开更多
The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between ge...The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, con- cluding that speciation with gene flow was unlikely under a ＂two-allele model＂ （where two traits were necessary for reproductive isolation） but that divergence could occur quite easily under a ＂one-allele model.＂ Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry （a tendency to remain where one was born） is known to occur in phyto- phagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe- rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe- rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philo- patry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 （5）： 658-666, 2013].展开更多
基金supported by the Natural Science Foundation for the Higher Education Institutions of Anhui Province of China(grant no.KJ 2021A0246).
文摘The gut microbiota of migratory waterbirds is affected by various complex factors,including cross-species transmission,which increases the risk of pathogen spreading among sympatric animals and poses a potential public health risk to humans.In this study,we investigated the microbial communities of wintering Bean Geese(Anser fabalis),Domestic Ducks(A.platyrhynchos domesticus),humans,and soil using high-throughput sequencing of the 16S rRNA gene region in Shengjin Lake,China.In total,6,046,677 clean reads were obtained,representing 41,119 operational taxonomic units(OTUs)across the four groups.The dominant microbial phyla were the Proteobacteria,Firmicutes,Bacteroidota,and Actinobacteriota.The Sorensen similarity index and alpha and beta diversity results showed that the gut microbial communities of Bean Geese and Domestic Ducks were more similar to those of the other pairs.Network analysis revealed that Faecalibacterium prausnitzii,Pseudomonas fragi,and Bradyrhizobium elkanii were hubs of the three major modules.Fourteen common microbiomes were iden-tified in Bean Geese,Domestic Ducks,humans,and soil in Shengjin Lake.A total of 96 potential pathogens were identified among the four groups,with 20 specific potentially pathogenic microbiomes found in the gut of Bean Geese.Some of these pathogens are responsible for significant financial losses in the poultry industry and pose risks to human health.Klebsiella pneumoniae,Morganella morganii,Escherichia coli,and Ralstonia insidiosa are potential core pathogens found in the four groups at Shengjin Lake that can cause diseases in humans and an-imals and facilitate cross-species transmission through various media.Therefore,humans are at risk of con-tracting these pathogens from migratory birds because of their frequent contact with domestic poultry.However,further studies are required to explore the potential pathogenic species and transmission pathways among sympatric wintering Bean Geese,Domestic Ducks,humans,and soil.
基金supported by Guangdong Science and Technology Plan Project(2013B02031005)Guangdong Academy of Science(GDAS)Special Project of Science and Technology Development(2017GDASCX-0107,2018 GDASCX-0107)+1 种基金Guangdong Forestry Special Project(0877-16GZTP01D060,1210-1741YDZB0401)Special Fund of Guangdong Nature Reserve(RYCG12-14,GDHS15SGFX07060,Cabot’s Tragopan monitoring)
文摘Background:The reliability of long-term population estimates is crucial for conservation and management purposes.Most previous studies assume that count indices are proportionally related to abundance;however,this assumption may not hold when detection varies spatially and temporally.We examined seasonal variations in abundance of three bird species(Cabot’s Tragopan Tragopan caboti,Silver Pheasant Lophura nycthemera,and Whitenecklaced Partridge Arborophila gingica) along an elevational gradient,using N-mixture models that take into account imperfect detection in our bird data.Methods:Camera-trapping was used to monitor temporal activity patterns of these species at Guangdong Nanling National Nature Reserve from December 2013 to November 2017(4 seasons per year).For abundance analysis(N-mixture modeling),we divided a year into 4 seasons,i.e.3 months per season,and performed the analysis by season.Elevation was incorporated into the N-mixture model as a covariate that may affect abundance.We compared the N-mixture model with a null model(no covariate model) and selected the better model based on AIC values to make an inference.Results:From 24 sampling sites,we obtained 6786 photographs of 8482 individuals of 44 bird species and 26 mammal species.Silver Pheasant was photographed much more frequently and showed higher temporal activity frequency than White-necklaced Partridge or Cabot’s Tragopan.Silver Pheasant was camera-captured most frequently in summer,and other two species in winters.All three species had two daytime activity peaks:between 6:00 a.m.and 10:00 a.m.,and between 5:00 p.m.and 7:00 p.m.,respectively.Our estimated abundance and detection probability from the N-mixture model were variable by season.In particular,all three species showed greater abundance in summer than in winter,and estimated abundance patterns of all three species were more similar with observed cameratrapping counts in summers.Moreover,in winter,elevation had a positive impact on abundance of Silver Pheasant and Cabot’s Tragopan,but not on White-necklaced Partridge.Conclusions:Our results demonstrate that the N-mixture model performed well in the estimation of temporal popu lation abundance at local fixed permanent plots in mountain habitat in southern China,based on the modeling of repeated camera-trapping counts.The seasonal differences in abundance of the three endemic bird species and the strong effect of elevation on abundance of two species in winter were only indicative of variations in spatio-tempora distribution within species and between species.In identifying suitable habitat for endemic pheasants,the positive elevational effect also suggests that more attention should be paid to conservation of areas with higher elevation in the Nanling Mountains.
基金Animal Ethics Committees at the Institute of Zoology, Chinese Academy of Sciences approved the ethics and protocol (IOZ14001) for the collection, handling, and husbandry of the study animalsBI J. H. (No.31660615) and SUN B. J. (No. 31870391 and 31500324) are supported by grants from the National Natural Science Foundation of China
文摘Sympatric reptiles are the ideal system for investigating temperature-driven coexistence. Understanding thermally physiological responses of sympatric lizards is necessary to reveal the physiological mechanisms that underpin the sympatric occurrence of reptiles. In this study, we used three lizard species, Eremias argus, E. multiocellata, and Phrynocephalus przewalskii, which are sympatric in the Inner Mongolia desert steppe, as a study system. By comparing their resting metabolic rates(RMR) and locomotion at different body temperatures, we aimed to better understand their physiological responses to thermal environments, which may explain the sympatric occurrence of these lizards. Our results showed that E. argus had significantly higher RMR and sprint speed than E. multiocellata, and higher RMR than P. przewalskii. In addition, the optimal temperature that maximized metabolic rates and locomotion for E. argus and E. multiocellata was 36°C, whereas for P. przewalskii it was 39°C. Our study revealed the physiological responses to temperatures that justify the sympatric occurrence of these lizards with different thermal and microhabitat preferences and active body temperatures. Eremias argus and E. multiocellata, which have lower body temperatures than P. przewalskii, depend on higher RMR and locomotion to compensate for their lower body temperatures in field conditions. Our study also highlights the importance of using an integrative approach, combining behavior and physiology, to explore the basis of sympatric occurrence in ectothermic species.
基金financially supported by The Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0501)National Natural Science Foundation of China(No.31772478,31501851)。
文摘Gut microbiota and host interactions co-evolve and develop into stably adapted microbial communities and play vital roles in maintaining the health of organisms.Diet is supposed to be an important driver of differences in gut microbiota,but previous studies would commonly use literature depictions,which are essential but inaccurate,to explain the effects of diet on the gut microbiota of wild birds.In this study,we collected intestinal samples from five sympatric flycatchers to compare the gut microbial differences using bacterial 16S rRNA genes from Illumina MiSeq platform.Over 1,642,482 quality-filtered sequences from 1816S rRNA libraries were obtained and distinct compositions and diversities of gut microbiota were found in five flycatchers.Their gut microbiota is mainly from the four bacterial phyla of Proteobacteria,Firmicutes,Actinomycetes,and Bacteroidetes,but at the genus level showed a significant difference.Functional predictions revealed that the metabolic capacity of the gut microbiota of five flycatchers is greatly distinguished at KEGG level 3.And multiple food fragments showed a significant correlation with gut microbiota.Besides,the significant differences in the specific composition of the diets of the five insectivorous flycatchers indicated the differentiation of dietary niches.The study of the gut microbiota and feeding habits of sympatric flycatchers would increase the understanding of the gut microbial diversity of wild birds,and also improve our cognition of the co-evolution and co-adaptation within the host gut microbiota relations.
文摘An individual-based model, EcoSim, was employed to investigate if specialized resource use could promote sympatric speciation. Prey individuals in the original version of EcoSim were supplied with a single primary food resource. A dual resource version with different food resources (Food 1 and Food 2) was also developed to create favorable conditions for the emergence of specialized food consumption among prey individuals. The single resource version was used as the control to determine the impact of the presence of multiple food resources on the occurrence of sympatric speciation. Each unit of Food 2 contained a higher amount of energy than Food 1, and Food 1 was more accessible than Food 2. Initially, prey individuals mostly fed on Food 1. How-ever, after the emergence of food specialization, the consumption rate of Food 2 signifi-cantly exceeded the consumption rate of Food 1;although prey individuals more frequently encountered Food 1. While sympatric speciation was observed in the dual resource version runs, we could not identify any sympatric species in the single resource version runs. Machine learning techniques were also employed to identify the most influential initial conditions leading to sympatric speciation. According to the obtained results, in most lineages sympatric speciation occurred at the beginning of the food specialization pro-cess. When the lineage had a high special diversity, the lineage needed two different criteria to diverge sympatrically: possessing high genetic diversity and a large population size. In support of previous findings, this study demonstrated that the most accurate determination of initial conditions leading to sympatric speciation can be obtained from lineages that are at the beginning of the divergence process. In conclusion, this study indicated that divergent foraging behavior could potentially lead to the sympatric emergence of new species in the absence of geographic isolation.
基金The National Natural Science Foundation of China (31672303, 31472013, 31772453)The Science and Technology Research and Development Project of Chengde (202002A088)。
文摘The efficacy of nest-site choice ultimately determines the breeding success of birds. Comparisons of the reproductive strategies of various bird species which inhabit the same habitat may provide insights on the evolution of the diverse life-history strategies in birds. In this study, nest-site choice and breeding success of four species of passerine birds that rely on reeds for reproduction were investigated in a wetland in Hebei, China. The four species were the Oriental reed warbler(Acrocephalus orientalis)(ORW), the blunt-winged warbler(Acrocephalus concinens)(BW), the reed parrotbill(Paradoxornis heudei)(RP), and the vinous-throated parrotbill(Sinosuthora webbiana)(VP). Our results showed that breeding nests of the four species were distributed in a mosaic pattern within the same habitat, with similar nest shapes/structures and nest-sites in the reeds. The only characteristics which differed significantly among the species were nest height above the water surface, height of reeds where nests were placed, and density of reeds around the nest site. In addition, the starting time of reproduction clearly differed for the four species. The breeding success rates of the four species were 34.5%(86/249) for ORW, 35.3%(6/17) for BW, 38.5%(15/39) for RP, and 40.9%(9/22) for VP in the two study years. The main factors affecting the breeding success were nest predation and poor weather conditions, like heavy rainstorms and wind, while nest parasitism by the common cuckoo(Cuculus canorus) represented an important factor for breeding failure only in the Oriental reed warbler. Our study demonstrated that these four sympatric species of passerine birds inhabiting the same wetland exhibit differences in terms of nest-site choice and breeding phenology.
基金supported by the Chinese Academy of Sciences(KSCX2-SW-105)the National Natural Science Foundation of China(Grant No.39725004)Chinese National Commission of Sciences and Technology(No:96-016-01-06).
文摘Electroantennogram (EAG) responses of male and female Oedipodinae grasshop-pers, Oedaleus decorus asiaticus B.-Bienko and Angaracris barabensis Pall to 37 plant volatile compounds were recorded. The two species have sympatric distribution and synchronous sea-sonal activity in Inner Mongolia Grasslands. They have different host plant preference with Oedaleus decorus asiaticus graminivorous and A. barabensis forbivorous. The EAG response profiles to 37 compounds of the two species and their both sexes were similar. Most of the green leaf volatiles elicited higher EAG responses in both species and sexes than terpenic compounds and some aromatic compounds. Strong EAG responses were elicited by 6-carbon alcohols (1-hexanol, Z-hexen-2-ol-1, E-2-hexen-1-ol, E-hexen-3-ol-1), aldehyde (E-2-hexen-1-al), ester (Z-hexen-3-yl acetate), and 7-carbon alcohols (1-heptanol) in both species and sexes. Monoterpenes with functional groups of alcohols and aldehydes were more stimulating than other monoterpenes tested. The sesquiterpenes tested elicited relatively low responses. Ben-zaldehyde elicited the highest responses for both species among aromatic components. Oedaleus decorus asiaticus showed higher EAG responses than A. barabensis to the green leaf volatiles, 1-decanol, 1-nonanol, 1-pentanol, hexanal, Z-hexen-3-yl acetate and to the sesquiter-penes (-)-trans-caryophyllene. Males have higher responses than females in Oedaleus decorus asiaticus. No sexual difference was observed in A. barabensis. Dose-dependent responses to six selected chemicals were observed from females. In both species, all the chemicals tested elicit EAG responses at concentration between 10-3 mol/L and 10-2 mol/L, except that the responses of A. barabensis to terpineol had a threshold concentration of 10-2 mol/L benzaldehyde and 1-hexanol had the highest slopes in dose curves, while 1-octen-3-ol showed the smallest slope in responses to the six chemicals tested. Comparative studies on the responses of two antennal sections and the whole antenna to six selected chemicals were carried out using females of both species. A significant EAG response was only recorded from the distal part of the antenna and not from the proximal seven segments.
基金Acknowledgments Thanks are given to two anonymous reviewers for their great input into this manuscript. This research was supported by the National Basic Research Program of China （973） （2010CB126200）, the National Nature Science Foundation of China （30700527）, and the Major Project of Cultivate New Varieties of Genetically Modified Organisms （2009ZX08011-007B, 2009ZX08012-005B and 2011ZX08012-005）, Fok Ying Tung Education Foundation （122033）, and the Doctoral Subject Foundation for the New Teachers of the Ministry of Education of the People＇s Republic of China （20070307002）.
文摘Effects of elevated CO2 （twice ambient vs. ambient） and Bt CrylAc transgene （Bt cotton cv. 33B vs. its nontransgenic parental line cv. DP5415） on the interspecific competition between two ecologically similar species of cotton aphid Aphis gossypii and whitefly biotype-Q Bemisia tabaci were studied in open-top chambers. The results indicated that elevated CO2 and Bt cotton both affected the population abundances of A. gossypii and biotype-Q B. tabaci when introduced solely （i.e., without interspecific competition） or two species coexisted （i.e., with interspecific competition）. Compared with ambient CO2, elevated COe increased the population abundances ofA. gossypii and biotype-Q B. tabaci as fed on Bt and nontransgenic cotton on 45 （i.e., seedling stage） and 60 （i.e., flowering stage） days after planting （DAP）, but only significantly enhanced aphid abundance without interspecific competition on the 45-DAP nontransgenic cotton and 60-DAP Bt cotton, and significantly increased whitefly abundance with interspecific competition on the 45-DAP Bt cotton and 60-DAP nontransgenic cotton. In addition, compared with nontransgenic cotton at elevated CO2, Bt cotton significantly reduced biotype-Q B. tabaci abundances without and with interspecific competition during seedling and flowering stage, while only significantly decreasing A. gossypii abundances without interspecific competition during the seedling stage. When the two insect species coexisted, the proportions ofbiotype-Q B. tabaci were significantly higher than those ofA. gossypii on Bt and nontransgenic cotton at the same CO2 levels, and elevated CO2 only significantly increased the percentages of biotype-Q B. tabaci and significantly reduced the proportions of A. gossypii on seedling and flowering nontransgenic cotton. Therefore, the effects of elevated CO2 were favorable for biotype-Q B. tabaci to out-compete A. gossypii under the predicted global climate change.
基金The study had no central budget.The field assistance,including accommodation,vehicle,and field assistants were facilitated by a local NGO(The Corbett Foundation).
文摘Background:The habitat resources are structured across different spatial scales in the environment,and thus animals perceive and select habitat resources at different spatial scales.Failure to adopt the scale-dependent framework in species habitat relationships may lead to biased inferences.Multi-scale species distribution models(SDMs)can thus improve the predictive ability as compared to single-scale approaches.This study outlines the importance of multi-scale modeling in assessing the species habitat relationships and may provide a methodological framework using a robust algorithm to model and predict habitat suitability maps(HSMs)for similar multi-species and multi-scale studies.Results:We used a supervised machine learning algorithm,random forest(RF),to assess the habitat relationships of Asiatic wildcat(Felis lybica ornata),jungle cat(Felis chaus),Indian fox(Vulpes bengalensis),and golden-jackal(Canis aureus)at ten spatial scales(500-5000 m)in human-dominated landscapes.We calculated out-of-bag(OOB)error rates of each predictor variable across ten scales to select the most influential spatial scale variables.The scale optimization(OOB rates)indicated that model performance was associated with variables at multiple spatial scales.The species occurrence tended to be related strongest to predictor variables at broader scales(5000 m).Multivariate RF models indicated landscape composition to be strong predictors of the Asiatic wildcat,jungle cat,and Indian fox occurrences.At the same time,topographic and climatic variables were the most important predictors determining the golden jackal distribution.Our models predicted range expansion in all four species under future climatic scenarios.Conclusions:Our results highlight the importance of using multiscale distribution models when predicting the distribution and species habitat relationships.The wide adaptability of meso-carnivores allows them to persist in human-dominated regions and may even thrive in disturbed habitats.These meso-carnivores are among the few species that may benefit from climate change.
基金supported by the National Natural Science Foundation of China(No.31470336 to X.G.and 31600178 to J.Y.)
文摘The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across many taxa, reproductive isolating barriers among multiple species （：〉2） that would represent the most common phenomenon in nature, remain to be clarified. Here, we use double digest restriction-site associated DNA （ddRAD） sequencing to examine patterns of hybridization at a sympatric site where three Ligularia species grow together and verify whether those patterns contribute to the maintenance of boundaries among species. The results based on the RAD SNP datasets indicated hybridization Ligularia cyathiceps x L. duciformis and L. duciformis x L. yunnanensis were both restricted toFls plus a few first-generation backcrosses and no gene introgression were identified, giving rise to strong reproductive isolation among hybridizing species. More- over, hybrid swarm simulation, using HYBRIDLAB, indicated the RAD SNP datasets had sufficient discriminatory power for accurate hybrid detection. We conclude that parental species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligualria in the eastern Qinghai-Tibetan Plateau and adjacent areas. Moreover, this study highlights the effectiveness of RAD sequencing in hybridization studies.
基金supported by Construction of Basic Conditions Platform of Sichuan Science and Technology Department (2019JDPT0020)China Biodiversity Observation Networks (Sino BON–Amphibian and Reptile)。
文摘A new species of the Asian leaf litter toad genus Leptobrachella is described from Sichuan Province, China. Molecular phylogenetic analyses based on mitochondrial and nuclear gene sequences clustered the new species as an independent clade nested into L. oshanensis species group. The new species could be distinguished from its congeners by a combination of following characters: body size moderate(25.8–32.6 mm in male, 33.7–34.1 mm in female);distinct black spots present on flanks;toes rudimentary webbed, with narrow lateral fringes, dermal ridges under toes interrupted at articulations;ventral belly cream white with variable brown specking;skin on dorsum relatively smooth with fine tiny granules or short ridges;iris copper above, silver bellow;greyish black patches on posterior thigh absent or small;spines on surface of chest absent in male during breeding season;nasals entirely or partially separated from sphenethmoid in male;dorsal surface of tadpoles semitransparent light brown, spots on tail absent, keratodont row formula I: 3+3(2+2)/2+2: I;calls simple, call series basically consist of repeated long calls, at dominant frequency(4831.9 ± 155.8) Hz and call duration(544.5 ± 146.8) ms. In addition, we made supplementary description on L. oshanensis including holotype, variations, tadpoles, skull and bioacoustics. Besides, this paper reports cases of femoral adipose glands in the genus Leptobrachella as first known sexual dimorphism skin glands for males of Megophryidae.
基金supported by the National Natural Science Foundation(31172101,30930016)。
文摘Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence,differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed.We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species(Tamias sibiricus,Apodemus peninsulae and Clethrionomys rufocanus)and the relationship of their pilfering abilities at the inter-and intraspecific levels.Our results showed that T.sibiricus exhibited a relatively stronger pilfering ability than A.peninsulae and C.rufocanus,as indicated by its higher recovery rate of artificial caches.Meanwhile A.peninsulae showed a medium pilfering ability and C.rufocanus displayed the lowest ability.We also noted that both cache size and cache depth significantly affected cache recovery in all three species.T.sibiricus scatter-hoarded more seeds than it larder-hoarded,A.peninsulae larder-hoarded more than scatter-hoarded,and C.rufocanus acted as a pure larder-hoarder.In T.sibiricus,individuals with lower pilfering abilities tended to scatter hoard seeds,indicating an intraspecific variation in hoarding propensity.Collectively,these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests,suggesting a strong connection between hoarding strategy and pilfering ability.
基金supported by the National Natural Science Foundation (31172101, 30930016)
文摘Although differences in food-hoarding tactics both reflect a behavioral response to cache pilferage among rodent species and may help explain their coexistence, differentiation in cache pilfering abilities among sympatric rodents with different hoarding strategies is seldom addressed. We carried out semi-natural enclosure experiments to investigate seed hoarding tactics among three sympatric rodent species (Tamias sibiricus, Apodemus peninsulae and Clethrionomys rufocanus) and the relationship of their pilfering abilities at the inter- and intraspecific levels. Our results showed that T. sibiricus exhibited a relatively stronger pilfering ability than A. peninsulae and C. rufocanus, as indicated by its higher recovery rate of artificial caches. Meanwhile A. peninsulae showed a medium pilfering ability and C. rufocanus displayed the lowest ability. We also noted that both cache size and cache depth significantly affected cache recovery in all three species. T. sibiricus scatter-hoarded more seeds than it larder-hoarded, A. peninsulae larder-hoarded more than scatter-hoarded, and C. rufocanus acted as a pure larder-hoarder. In T. sibiricus, individuals with lower pilfering abilities tended to scatter hoard seeds, indicating an intraspecific variation in hoarding propensity. Collectively, these results indicated that sympatric rodent species seem to deploy different food hoarding tactics that allow their coexistence in the temperate forests, suggesting a strong connection between hoarding strategy and pilfering ability.
基金supported by the National Basic Research Program of China (2009CB125903)the Innovation Fund for graduate student in Southwest University of China (kb2011014)
文摘Invasion of the oriental fruit lfy, Bactrocera dorsalis, into new niches containing different food sources （a process referred to as host shift）, may cause population genetic differentiation and sympatric speciation. To attempt to infer that experimentally, test populations were established by transferring a subset of the original populations, which had been grown on banana for many generations, onto navel orange, and then subculturing the navel orange population and banana population for at least 20 generations. Four pairs of SSR primers with high polymorphism on laboratory strains were used to detect population genetic differentiation. All six tested populations （the 5th, 10th and 15th generations of B. dorsalis fed on banana and navel orange, respectively） were found to have low genetic diversity. Furthermore, the genetic diversity of the navel orange populations was found to decline after being crossed for several generations. Populations initially were deviated from Hardy-Weinberg equilibrium, however, equilibrium was achieved with increasing numbers of generations in both of the host populations. Limited gene lfows were found among the six populations. The Nei’s standard genetic distances between the two host populations of the same generation were initially low, but increased with generation number. Genetic distances between banana and navel orange populations of the same generation were lower than genetic distances between different generations grown on the same host plant. Analysis of molecular distance （AMOVA） results based on generation groups and host groups demonstrated that genetic variation among generations was greater than that between the two host populations. The results indicated that population genetic differentiation occurred after the host shift, albeit at low level. Biogeography and taxonomy of the B. dorsalis complex revealed that speciation of B. dorsalis might be tightly associated with host shift or host specialization of B. dorsalis following dispersal.
基金supported by the National Natural Science Foundation of China(Grant Nos.31601856 and 31670398)。
文摘Natural hybridization,which often occurs between closely related species exhibiting sympatric or parapatric distributions,is an important source of genetic variation within populations.The closely related Jankowski’s Bunting(Emberiza jankowskii)and Meadow Bunting(E.cioides)are similar in morphology and genetics,occupy overlapping niches,and are sympatric in eastern Inner Mongolia.Previous studies have reported trans-species polymorphisms of alleles between the two species,as well as an unexpectedly high genetic diversity of the endangered E.jankowskii.We speculate that introgressive hybridization has occurred between the two species and contributed to the additional unexpected variation to E.jankowskii.We used mitochondrial NADH dehydrogenase subunit 2(ND2)gene and 15 nuclear microsatellite markers to compare the genetic diversity of E.jankowskii and E.cioides,and inferred the origin of trans-species polymorphisms between the two species by phylogenetic reconstruction and Bayesian cluster analysis.The two species could be clearly distinguished by population cluster analysis.Despite the large number of mutational differences,we still detected sharing of major haplotypes and the presence of hybrids between the two species.Our study confirmed that weak introgressive hybridization has occurred between sympatric E.jankowskii and E.cioides,which may be mediated by female E.cioides individuals,and that interspecific introgression has contributed to the maintenance of high genetic diversity in E.jankowskii.While being wary of the potential negative effects of introgressive hybridization,we suggest that expanding the habitat of E.jankowskii remains the most effective conservation strategy at present.
基金supported by National Natural Science Foundation of China(Nos.31772483 and 31372218 to CD,No.31900371 to YY).
文摘Background:Interspecific competition is known to be strongest between those species that are both closely related and sympatric.Egrets are colonially nesting wetland birds that often overlap and can therefore be expected to compete in roosting and nesting habitat as well as in diet.According to the niche partitioning hypothesis,it is to be expected that these similar species would show differentiation in at least one of the main niche dimensions to reduce competition.We tested niche partitioning between the colonially nesting Little Egret(Egretta garzetta)and Cattle Egret(Bubulcus ibis)in temporal,spatial and trophic dimensions.Methods:Field study was conducted in three mixed egret colonies in Yangxian County,southwest Shaanxi Prov-ince,central China.For each nest colony we recorded its spatial location,the height of nesting trees and of nests,the height of roosting trees and of roosting individuals within the trees.We determined the first egg-laying and first hatching dates of the two species.Craw dissection of storm-killed egret nestlings was used to measure the diet.Six transects were surveyed to study foraging habitat selection.Results:We found that hatching time of Little Egrets peaked earlier(by about 1 month)than that of Cattle Egrets.Cattle Egrets nested and roosted higher than Little Egrets.The foraging habitats used by Little Egrets were dominated by river banks(73.49%),followed by paddy fields(13.25%)and reservoirs(10.84%),whereas Cattle Egret foraging sites were characterized by grasslands(44.44%),paddy fields(33.33%)and river banks(22.22%).Little Egrets consumed more fishes(65.66%)and Odonata larvae(13.69%)than Cattle Egrets,while Cattle Egrets were found feeding mainly on Coleoptera(29.69%)and Orthoptera(23.29%).Little Egrets preyed on larger mean biomasses of food items than Cattle Egrets.Conclusions:Our results confirm the niche partitioning hypothesis as a mechanism for coexistence among ecologi-cally similar species.In two coexisting egret species,niche partitioning is multidimensional,such that the two coexist-ent species occupy differing ecological space based on all three temporal,spatial and trophic niche dimensions.
基金the National Natural Science Foundation of China(grant no.31772471)the self-determined research funds of CCNU from the colleges’basic research and operation of MOE(grant no.CCNU17A02017).
文摘Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals.However,exactly how the subordinate species coexists with superior species is unknown.In the forests west of Beijing City,intense asymmetrical interactions of food competition exist among granivorous rodents(e.g.Apodemus peninsulae,Niviventer confucianus,Sciurotamias davidianus and Tscherskia triton)that have broadly overlapping habitats and diets but have varied body size(range 15-300 g),hoarding habits(scatter vs larder)and/or daily rhythm(diurnal vs nocturnal).The smallest rodent,A.peninsulae,which typically faces high competitive pressure from larger rodents,is an ideal model to explore how subordinate species coexist with superior species.Under semi-natural enclosure conditions,we tested responses of seed-hoarding behavior in A.peninsulae to intraspecific and interspecific competitors in the situations of pre-competition(without competitor),competition(with competitor)and post-competition(competitor removed).The results showed that for A.peninsulae,the intensity of larder-hoarding increased and the intensity of scatter-hoarding declined in the presence of intraspecifics and S.davidianus,whereas A.peninsulae ceased foraging and hoarding in the presence of N.confucianus and T.triton.A.peninsulae reduced intensity of hoarding outside the nest and moved more seeds into the nest for larder-hoarding under competition from intraspecific individuals and S.davidianus.In most cases,the experimental animals could recover to their original state of pre-competition when competitors were removed.These results suggest that subordinate species contextually regulate their food-hoarding strategies according to different competitors,promoting species coexistence among sympatric animals that have asymmetrical food competition.
基金supported by the National Natural Science Foundation of China (31170184, U1202261, 31000109)the China Scholarship Council (for C. S.’s study in Canada)
文摘Reproductive isolation is a fundamental require- ment for speciation and includes several sequential stages. Few studies have determined the relative contributions of pre- and post-zygotic reproductive isolation in plants, especially between relative species with clear differentiation in flower form. To investigate the mechanisms responsible for repro- ductive isolation in sympatric A4ussaenda pubescens var. alba and Mussaenda shikokiana （Rubiaceae） in Guangxi Province, China, we made observations of flowering phenology, patterns of insect visitation, and conducted pollination experiments, including artificial hybridization. The two species had over- lapping flowering times and were pollinated by overlapping pollinators; however, their relative importance differed significantly with M. pubescens visited more commonly by bees and M. shikokiana more frequently by butterflies. Using vegetative and floral characters and molecular evidence based on nuclear ribosomal internal and external transcribed spacer regions we detected seven naturally occurring hybrids among a sample of approximately 125 individuals. Hybrids were characterized by morphologies that most closely resembled their maternal parents based on chloroplast evidence. Studies of artificially synthesized and natural hybrids demonstrated that hybrid seed had very low germination rates and naturally occurring hybrids exhibited pollen sterility. Post-zygotic reproductive isolating mechanisms play a primary role in limiting gene exchange between co-occurring species and maintaining species integrity in areas of sympatry.
文摘Sitobion avenae （E） is an important cereal pest worldwide that can survive on various plants in the Poaceae, but divergent selection on different host plants shouldpromote the evolution of specialized genotypes or host races. In order to evaluate their resource use strategies, clones of S. avenae were collected from oat and barley. Host-transfer experiments for these clones were conducted in the laboratory to compare their fitness traits. Our results demonstrated that barley clones had significantly lower fecundityand tended to have longer developmental times when transferred from barley to oat. However, oat clones developed faster after they were transferred to barley. Clones fromoat and barley had diverged to a certain extent in terms of fecundity and developmental time of the nymphs. The separation of barley clones and oat clones of S. avenae was alsoevident in a principal component analysis. Barley clones tended to have higher broad-sense heritabilities for fitness traits than oat clones, indicating the genetic basis of differentiationbetween them. Barley clones showed significantly higher extent of specialization compared to oat clones from two measures of specialization （i.e., Xsp and Ysp）. Therefore, barleyclones were specialized to a certain extent, but oat clones appeared to be generalized. The fitness of S. avenae clones tended to increase with higher extent of specialization. Theevolution toward ecological specialization in S. avenae clones, as well as the underlying genetic basis, was discussed.
文摘The study of speciation genetics is primarily concerned with identifying the genetic traits that allow divergent selec- tion to overcome the homogenizing effects of gene flow. Felsenstein reviewed this race between gene flow and selection, con- cluding that speciation with gene flow was unlikely under a ＂two-allele model＂ （where two traits were necessary for reproductive isolation） but that divergence could occur quite easily under a ＂one-allele model.＂ Despite this finding, much of the sympatric speciation research involving phytophagous insects has relied on a two-trait model, where insects evolve both preferences for and increased performance on novel host plants. Philopatry （a tendency to remain where one was born） is known to occur in phyto- phagous insects and is a single trait isolation mechanism. However, it is traditionally invoked as simply augmenting reproductive isolation. Species in the Enchenopa binotata complex are believed to have speciated in sympatry. They exhibit host plant prefe- rences, host specific performance advantages and strong philopatry. We experimentally shifted E. binotata to evolutionarily novel host plants. Previous research has demonstrated that the experimental population of insects possesses genetic variation in prefe- rence and performance to the novel host. The degree of philopatry at mating and egg-laying was assayed for the first four years under full choice conditions. Host plant preference and performance was assayed after eight years. Philopatry was an immediate and strong isolating mechanism, while preference for and performance on the novel host lagged. We therefore suggest that philo- patry may be a more important mechanism in the early stages of a host shift than previously believed [Current Zoology 59 （5）： 658-666, 2013].
