小兴安岭阔叶红松林地表甲虫Metacommunity格局

Metacommunity理论框架为理解生物群落的时空格局及其构建机制提供了一个强有力的方法。然而,少有研究揭示土壤动物metacommunity的格局及其构建机制,小尺度空间的研究更是少见。于2015年分别在凉水和丰林小兴安岭典型阔叶红松林长期动态监测样地内,通过空间直观定位调查监测的方法获得地表甲虫群落,揭示小尺度空间(300 m)地表甲虫metacommunity的格局,并进一步分析地形、土壤因子与这种metacommunity格局的相关性。结果表明:镶嵌型(nestedness)和随机型(random)是小尺度空间地表甲虫metacommunity的常见格局。地表甲虫的metacommunity格局具有类群依赖性,步行虫科和葬甲科多形成镶嵌型格局,而隐翅虫科则仅形成随机型格局。地表甲虫metacommunity格局具有季节波动性,在相对温暖的季节易形成显著的镶嵌型格局,而在相对寒冷的季节多为随机型格局。凉水和丰林地表甲虫的metacommunity格局没有明显差异。地形和土壤因子对地表甲虫metacommunity格局有重要的影响,该影响过程相对复杂,依类群和时间而异。本实验表明镶嵌型和随机型是小尺度空间小兴安岭典型阔叶红松林地表甲虫的常见格局,地形、土壤因子对这些格局的形成有重要的影响。

The impact of earlier flood recession on metacommunity diversity of wintering waterbirds at shallow lakes in the middle and lower Yangtze River floodplain

The hydrological regime in wetlands plays an important role in the process of wintering waterbird metacommunity assemblage.However,increasing frequency of extreme climate and the intensification of human activities,such as the construction of sluices and dams,have resulted in frequently abnormal hydrological regime in the middle and lower Yangtze River floodplain.In recent years,earlier flood recession has become one of the main hydrological problems faced in the shallow lakes,having a great impact on wetland biodiversity.It is necessary to understand the impact of earlier flood recession on waterbirds,an indicator of wetland biodiversity,and the metacommunity concept is helpful to elucidate the underlying mechanism involved in the processes of assemblage by waterbird communities.In this study,we surveyed the wintering waterbirds at three sub-lakes of Caizi Lakes during 2019-2020 and 2020-2021 and compared the richness,abundance,alpha and beta diversity of waterbirds in and among local metacommunities under earlier flood recession and normal hydrological regime.The results showed that the earlier flood recession reduced the species richness in the early stage and abundance in the late stage,it also reduced the Shannon-Wiener index in the early stage and increased the dissimilarity between and within waterbird metacommunities in the late stage.The partition of beta diversity showed that the turnover component played a major role in the process of waterbird metacommunity assemblage.It was found that the earlier flood recession reduced the richness,abundance in different stages of flood recession,which also increased the turnover of waterbirds.Metacommunities with high habitat heterogeneity had better resistance to abnormal hydrological regime,which resulted in high dissimilarity between and within metacommunities.The results of this study provide important information for waterbird conservation and water level management at shallow lakes in the middle and lower Yangtze River floodplain.

Ontogenetic trait variation and metacommunity effects influence species relative abundances during tree community assembly

Predicting species abundance is one of the most fundamental pursuits of ecology.Combining the information encoded in functional traits and metacommunities provides a new perspective to predict the abundance of species in communities.We applied a community assembly via trait selection model to predict quadrat-scale species abundances using functional trait variation on ontogenetic stages and metacommunity information for over 490 plant species in a subtropical forest and a lowland tropical forest in Yunnan,China.The relative importance of trait-based selection,mass effects,and stochasticity in shaping local species abundances is evaluated using different null models.We found both mass effects and trait selection contribute to local abundance patterns.Trait selection was detectable at all studied spatial scales(0.04e1 ha),with its strength stronger at larger scales and in the subtropical forest.In contrast,the importance of stochasticity decreased with spatial scale.A significant mass effect of the metacommunity was observed at small spatial scales.Our results indicate that tree community assembly is primarily driven by ontogenetic traits and metacommunity effects.Our findings also demonstrate that including ontogenetic trait variation into predictive frameworks allows ecologists to infer ecological mechanisms operating in community assembly at the individual level.

Environmental filtering and spatial processes equally contributed to macroinvertebrate metacommunity dynamics in the highly urbanized river networks in Shenzhen, South China

Background:Disentangling the relative roles of environmental filtering and spatial processes in structuring ecological communities is a central topic in metacommunity ecology.Metacommunity ecology in the temperate river ecosystems has been well developed,while less attention has been paid to subtropical urban river networks.Here,we examined the ecological factors and seasonal difference in structuring macroinvertebrates metacommunity assembly in the subtropical urban river networks in Shenzhen,South China.Results:Our results revealed that there was no significant distinction of macroinvertebrate community composition among seasons,with only the relative abundance of Mollusca and Odonata significantly differed in both wet and dry seasons.One possible explanation was that most macroinvertebrates are generally pollution-tolerant taxa characterized with nonseasonal life cycle.In addition,distance-based redundancy analysis and variation partitioning approach revealed that metacommunity was determined equally by the environmental and dispersal-related factors.Further,our results showed that,although a slight temporal variation of relative contribution,the identity and explanation power of ecological factors were different among seasons.Specifically,stronger environmental filtering structuring community dynamics was observed in the dry than wet seasons,which might be owing to higher environmental heterogeneity under a low water-flow condition.Moreover,we detected that the influence of spatial processes was stronger in the wet than dry seasons,indicating an obvious dispersal processes due to high connectivity among sites.Conclusion:Overall,our results revealed that environmental and spatial factors equally explained variations of macroinvertebrate metacommunity,implying the necessity of considering dispersal-related processes structuring ecological communities in river bioassessment programs.Moreover,degraded habitat conditions and water quality were the predominant factors that affected macroinvertebrate communities,indicating the significance and feasibility of improving local abiotic conditions to sustain local biodiversity.Further,our findings revealed the importance of seasonal dynamics of these urban river networks in structuring macroinvertebrate metacommunity.Thereby,our study improves the understanding of ecological processes governing macroinvertebrate metacommunity and underlines the idea that community ecology studies should go beyond the single snapshot survey in river networks.

β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.

Spatiotemporal distribution of seasonal bird assemblages on land-bridge islands: linking dynamic and static views of metacommunities

Background: Although assessing temporal dynamics of populations is crucial for understanding metacommunities, empirical studies have primarily analyzed only static snapshots of communities. Here, we present a holistic view of how species traits and habitat characteristics relate to metacommunity dynamics and use it to test for differences in the spatiotemporal distribution of seasonal bird assemblages. Methods: We surveyed forest birds in breeding and winter seasons within 36 islands for 9 years. We then grouped birds into four landbird assemblages, selected on the basis of published differences in biology or ecology: winter residents, migratory winter visitors, breeding summer residents, and migratory summer visitors. We estimated dynamic species colonization and extirpation through the 9-year period, and evaluated the associations among island attributes, species attributes and community composition. Results: Overall, winter and summer residents showed strong associations between composition and habitat structure of the islands. In addition, winter and summer residents on large islands had lower extirpation and turnover than winter and summer visitors. Visitor assemblages showed no significant habitat associations, and in winter had high extirpation rates and small body sizes. By contrast, local extirpation of summer visitors was correlated with local species richness, indicating a likely effect of competition on extirpation. Conclusions: Our results demonstrated repeated patterns among species composition, bird traits, habitat/island characteristics and observed metacommunity dynamics. Winter and summer residents best matched species sorting and patch dynamics, respectively, due to differences in resource availability and requirements of overwinter survival versus breeding. Summer visitors were consistent with species sorting and winter visitors were randomly distributed, likely because of interactions with resident competitors. Our results highlight that coexisting seasonal migrant and resident assemblages differ in their spatial dynamics, with consequences for relevant conservation and management strategies.

The assembly of plant-patch networks in Mediterranean alpine grasslands

Aims Harsh environmental conditions in alpine ecosystems shape vegetation structure into patches,where many different plant species cluster and grow together.Yet,which factors are important for the structure and dynamics of such plant–patch networks remains poorly understood.We aim to assess which and how environmental and biotic factors predict the assembly of plant–patch networks along a mountain range.Methods We examined the distribution of plant species in more than 5500 vegetation patches in 37 Mediterranean alpine grasslands distributed along a 500 m altitudinal gradient(National Park of Sierra Guadarrama,Spain).We established a plant–patch network for each grassland community and analyzed how nestedness and modularity vary with environmental(altitude,insolation and soil conditions)and biotic factors(number of species per plot,mean patch area and total pasture area).Important Findings Plant–patch networks showed consistent,non-random patterns characterized by a nested,but not modular,structure,which suggests that positive associations among co-occurring specialists promote their growth within patches as subsets of a pool with more generalist species.Both nestedness and modularity of plant–patch networks varied among grasslands.Specifically,nestedness decreased with increasing species per plot and increased with mean patch area,while it was independent of environmental variables;modularity increased with increasing pasture area and species per plot.The negative relationship between species per plot and nested patterns may be linked to the restricted number of species that can coexist within the same patch at a given size.Moreover,the positive relationship between patch size and nestedness indicates that the growth of rare plant species within vegetation patches occupied by more abundant species is facilitated in bigger rather than smaller patches.Furthermore,these results indicate that the nested assembly of vegetation patches may be independent of abiotic conditions.These findings suggest that large and unfragmented vegetation patches are fundamental for the maintenance of plant diversity in alpine grasslands.Looking at species distribution at fine spatial scales may shed new light on the biotic processes underlying plant network assembly and provide novel ways for conserving biodiversity.

Genetic adaptation as a biological buffer against climate change:Potential and limitations

Climate change profoundly impacts ecosystems and their biota,resulting in range shifts,novel interactions,food web alterations,changed intensities of host–parasite interactions,and extinctions.An increasing number of studies have documented evolutionary changes in traits such as phenology and thermal tolerance.In this opinion paper,we argue that,while evolutionary responses have the potential to provide a buffer against extinctions or range shifts,a number of constraints and complexities blur this simple prediction.First,there are limits to evolutionary potential both in terms of genetic variation and demographic effects,and these limits differ strongly among taxa and populations.Second,there can be costs associated with genetic adaptation,such as a reduced evolutionary potential towards other(human-induced)environmental stressors or direct fitness costs due to tradeoffs.Third,the differential capacity of taxa to genetically respond to climate change results in novel interactions because different organism groups respond to a different degree with local compared to regional(dispersal and range shift)responses.These complexities result in additional changes in the selection pressures on populations.We conclude that evolution can provide an initial buffer against climate change for some taxa and populations but does not guarantee their survival.It does not necessarily result in reduced extinction risks across the range of taxa in a region or continent.Yet,considering evolution is crucial,as it is likely to strongly change how biota will respond to climate change and will impact which taxa will be the winners or losers at the local,metacommunity and regional scales.

Don’t stop me now, I’m having such a good time! Czechoslovakian wolfdogs renovate the motivation to play with a bow

Dogs engage in play behavior at every age and the play bow is their most iconic playful posture.However,the function of this posture is still under debate.Here,we selected the Czechoslovakian Wolfdog(CWD)as a model breed to clarify the function of the play bow.We analyzed frame-by-frame 118 sessions of 24 subjects and recorded 76 play bow events.We found that all the play bows were performed in the visual field of the playmate suggesting that the sender takes into account the attentional state of the receiver when releasing the signal.By drawing survival curves and using log-rank test we found that play bow was mainly performed during a short pause in an ongoing session and that its performance triggered the playmate’s reaction again.These findings show that play bow functions in restoring the partner motivation to play.Finally,by using a sequential analysis and a generalized mixed model,we found no evidence supporting the metacommunicative function of the play bow.The signal did not necessarily precede a contact offensive behavior(e.g.,play biting and play pushing)and it was not affected by the level of asymmetry of the play session.In conclusion,in CWDs play bow can be considered a visual signal useful to maintain the motivation to play in the receiver.Therefore,we suggest that the mismatched number of play bows emitted by the 2 players in a given session can be predictive of their different motivations to play.

Visual communication in social play of a hierarchical carnivore species:the case of wild spotted hyenas

Communication relies on signals that can be produced via different sensory modalities to modify receivers’behavior.During social interactions,the possibility to perceive subtle visual cues enhances the use of facial expressions to exchange information.One of the most appropriate fields to explore the specific design features of visual signals is play fighting.Here,we explored the production and potential role of Relaxed Open Mouth(ROM)and Head Bobbing(HB)in regulating play fighting of wild spotted hyenas Crocuta crocuta,a highly hierarchical carnivore species.In accordance with the assumptions of the signal optimization theory,wild hyenas produced ROM and HB almost exclusively when the sender was in direct visual contact with the receiver thus suggesting that senders were attentive to the playmates’face.Contrary to HB,the sequential analysis revealed that ROM often anticipated offensive patterns such as play biting thus supporting the hypothesis that ROM,but not HB,is a metacomunicative signal.Moreover,when the offensive patterns were biased toward one of the 2 players,the session was punctuated by a higher number of ROMs.Our findings support the general hypothesis that these 2 visual signals can play different roles in the management of play fighting in this carnivore species.The complementary use of ROM and HB would suggest that spotted hyenas are highly competent and fast in processing facial displays of different nature to correctly“read others’intentions”and respond with appropriate motor actions to avoid misunderstanding during one of the most multifaceted and risky social interaction.