
多様な群集では、ごく一部の種が大部分を占める優位性の状態から、多くの種が均等に存在する平等性の状態への移行が起こる。この移行は、環境変動や移入率の変化によって引き起こされる。


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多様な群集における優位性から平等性への移行

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キリンマウンテン国立公園の肉食動物は、時間的、空間的、および食性ニッチの分割によって共存している。頂点肉食動物は時間的または食性的に重複し、メソ肉食動物は食性的に高い重複を示すが、空間的および時間的ニッチ分割によって共存している。頂点肉食動物とメソ肉食動物の間では、空間的および食性ニッチ分割が共存を促進している。


Carnivores play key roles in maintaining ecosystem structure and function as well as ecological processes. Understanding how sympatric species coexist in natural ecosystems is a central research topic in community ecology and biodiversity conservation. In this study, we explored intra- and interspecific niche partitioning along spatial, temporal, and dietary niche partitioning between apex carnivores (wolf Canis lupus , snow leopard Panthera uncia , Eurasian lynx Lynx lynx ) and mesocarnivores (Pallas’s cat Otocolobus manul , red fox Vulpes vulpes , Tibetan fox Vulpes ferrilata ) in Qilian Mountain National Park, China using camera trapping data and DNA metabarcoding sequencing data. Our study showed that apex carnivore species had more overlap temporally (coefficients of interspecific overlap ranging from 0.661 to 0.900) or trophically (Pianka’s index ranging from 0.458 to 0.892), mesocarnivore species had high dietary overlap with each other (Pianka’s index ranging from 0.945 to 0.997), and apex carnivore and mesocarnivore species had high temporal overlap (coefficients of interspecific overlap ranging from 0.497 to 0.855). Large dietary overlap was observed between wolf and snow leopard (Pianka’s index=0.892) and Pallas’s cat and Tibetan fox (Pianka’s index=0.997), suggesting the potential for increased resource competition for these species pairs. We concluded that spatial niche partitioning is likely to key driver in facilitating the coexistence of apex carnivore species, while spatial and temporal niche partitioning likely facilitate the coexistence of mesocarnivore species, and spatial and dietary niche partitioning facilitate the coexistence between apex and mesocarnivore species. Our findings consider partitioning across temporal, spatial and dietary dimensions while examining diverse coexistence patterns of carnivore species in Qilian Mountain National Park, China. These findings will contribute substantially to current understanding of carnivore guilds and effective conservation management in fragile alpine ecosystems.

### Competing Interest Statement

The authors have declared no competing interest.

Different coexistence patterns between apex carnivores and mesocarnivores based on temporal, spatial, and dietary niche partitioning analysis in Qilian Mountain National Park, China

雲南省キリンマウンテン国立公園における頂点肉食動物とメソ肉食動物の時間的-空間的-および食性ニッチ分割に基づく共存パターンの分析


雲南省キリンマウンテン国立公園における頂点肉食動物とメソ肉食動物の時間的、空間的、および食性ニッチ分割に基づく共存パターンの分析



種間相互作用の性質と強さが、環境撹乱に対する共存の堅牢性を決定する。


In Lotka-Volterra community models, given a set of biotic interactions, recent approaches have analysed the probability of finding a set of species intrinsic growth rates (representing intraspecific demographic features) that will allow coexistence. Several metrics have been used to quantify the fragility of coexistence in the face of variations in those intrinsic growth rates (representing environmental perturbations), thus probing a notion of ‘distance’ to the edge of coexistence of the community. Here, for any set of interacting species, we derive an analytical expression for the whole distribution of distances to the edge of their coexistence. Remarkably, this distribution is entirely driven by (at most) two characteristic distances that can be directly computed from the matrix of species interactions. We illustrate on data from experimental plant communities that our results offer new ways to study the contextual role of species in maintaining coexistence, and allow us to quantify the extent to which intraspecific features and biotic interactions combine favorably (making coexistence more robust than expected), or unfavourably (making coexistence less robust than expected). Our work synthesizes different study of coexistence and proposes new, easily calculable metrics to enrich research on community persistence in the face of environmental disturbances.

### Competing Interest Statement

The authors have declared no competing interest.

The distribution of distances to the edge of species coexistence

環境撹乱に対する種共存の堅牢性について


氷河後退に伴い、見かけ上は裸地であった場所に新しい生態系が発達する。この過程を理解することは、気候変動が微小生息地と生物群集に与える影響を理解する上で重要である。


Across 46 proglacial landscapes worldwide, environmental properties and biodiversity have&nbsp;shown complex patterns of change&nbsp;since glaciers retreated.

The development of terrestrial ecosystems emerging after glacier retreat - Nature

氷河後退後に出現する陸上生態系の発達


熱帯林の劣化が進むにつれ、生物多様性が大幅に減少する閾値が存在する。


Framework to assess the conservation value of logged tropical forests.

Forest-degradation thresholds shape tropical biodiversity

熱帯林の劣化が生物多様性に及ぼす影響の閾値


気候温暖化に伴う鳥類群集の熱適応化は、生息地断片化によって促進される。小さな島や孤立度の高い島では、暖温適応種の定着が速く、一方で寒冷適応種の絶滅が早い。


Climatic warming can shift community composition driven by the colonization-extinction dynamics of species with different thermal preferences; but simultaneously, habitat fragmentation can mediate species’ responses to warming. As this potential interactive effect has proven difficult to test empirically, we collected data on birds over 10 years of climate warming in a reservoir subtropical island system that was formed 65 years ago. We investigated how the mechanisms underlying climate-driven directional change in community composition were mediated by habitat fragmentation. We found thermophilization driven by increasing warm-adapted species and decreasing cold-adapted species in terms of trends in colonization rate, extinction rate, occupancy rate and population size. Critically, colonization rates of warm-adapted species increased faster temporally on smaller or less isolated islands; cold-adapted species generally were lost more quickly temporally on closer islands. This provides support for dispersal limitation and microclimate buffering as primary proxies by which habitat fragmentation mediates species range shift. Overall, this study advances our understanding of biodiversity responses to interacting global change drivers.

### Competing Interest Statement

The authors have declared no competing interest.

Habitat fragmentation mediates the mechanisms underlying long-term climate-driven thermophilization in birds

気候変動と生息地断片化が鳥類の群集組成の長期的な変化に及ぼす相互作用的影響


人間の活動は、地上哺乳類の時空間的関連性を増加させ、野生生物の共存と持続可能性、さらには生態系機能に重大な影響を及ぼす可能性がある。


Spatial and temporal associations between sympatric species underpin biotic interactions, structure ecological assemblages, and sustain ecosystem functioning and stability. However, the resilience of interspecific spatiotemporal associations to human activity remains poorly understood, particularly in mountain forests where anthropogenic impacts are often pervasive. Here we applied context-dependent Joint Species Distribution Models to a systematic camera-trap survey dataset from a global biodiversity hotspot in eastern Himalaya to understand how prominent human activities in mountain forests influence species associations within terrestrial mammal communities. We obtained 10,388 independent detections of 17 focal species (12 carnivores and five ungulates) from 322 stations over 43,163 camera days of effort. We identified a higher incidence of positive associations in habitats with higher levels of human modification (87 %) and human presence (83 %) compared to those located in habitats with lower human modification (64 %) and human presence (65 %) levels. We also detected a significant reduction of pairwise encounter time at increasing levels of human disturbance, corresponding to more frequent encounters between pairs of species. Our findings indicate that human activities can push mammals together into more frequent encounters and associations, which likely influences the coexistence and persistence of wildlife, with potential far-ranging ecological consequences.

### Competing Interest Statement

The authors have declared no competing interest.

Human disturbance increases spatiotemporal associations among mountain forest terrestrial mammal species

人間の攪乱が山岳森林の地上哺乳類種間の時空間的関連性を増加させる


アマゾンの森林は干ばつに対して複雑な反応を示し、回復力と脆弱性の両方を示す。この反応は気候変動のみでは説明できず、水位深さ、土壌肥沃度、植生特性などの要因によって決まる。


Drought response is structured by water-table depth in higher-fertility Southern Amazonia, whereas lower-fertility Northern Amazonia supports more-drought-resilient forests independent of water-table depth.

Amazon forest biogeography predicts resilience and vulnerability to drought - Nature

アマゾンの森林生物地理学が干ばつに対する回復力と脆弱性を予測する


種の共分布パターンから種間相互作用を正確に推定することは困難であり、相互作用の統計的特性を推定することが重要である。


One of the more difficult challenges in community ecology is inferring species interactions on the basis of patterns in the spatial distribution of organisms. At its core, the problem is that distributional patterns reflect the ‘realized niche’, the net result of a complex interplay of processes involving dispersal, environmental, and interaction effects. Disentangling these effects can be difficult on at least two distinct levels. From a statistical point of view, splitting a population’s variation into contributions from its interaction partners, abiotic environment and spatial proximity requires ‘natural experiments’ where all three factors somehow vary independently from each other. On a more conceptual level, it is not even clear how to meaningfully separate these processes: for instance, species interactions could depend on the state of the abiotic and biotic environment, and these two processes may combine in highly non-additive ways. Here we show that the latter issue arises almost inescapably, even in a simple theoretical setting designed to minimize it. Using a model of competitive metacommunity dynamics where direct species interactions are assumed to be context-independent, we show that inferring these interactions accurately from cross-species correlations is a major challenge under all but the most restrictive assumptions. However, we also find that it is possible to estimate the statistical moments (mean value and variance) of the species interactions distribution much more robustly, even if the precise values cannot be inferred. Consequently, we argue that study of multi-species spatial patterns can still be informative for theoretical approaches that build on statistical distributions of species parameters to predict macroscopic outcomes of community assembly.

### Competing Interest Statement

The authors have declared no competing interest.

Getting More by Asking for Less: Linking Species Interactions to Species Co-Distributions in Metacommunities

共生種の共分布から種間相互作用を推定する際の課題


ラフレッグドハヤブサは、非繁殖期に「フォックストロット移動」と呼ばれる新しい移動パターンを示し、その非繁殖域は時間的に変化する「動的な範囲」を形成する。


Advancements in tracking technologies have revolutionized our understanding of bird migrations, revealing a diverse array of migratory behaviors. We propose a new pattern of migratory behavior termed ‘foxtrot migration,’ characterized by alternating quick and slow phases during the non-breeding period. This behavior involves directional and continuous movements, distinct from traditional seasonal itinerancy or forage-on-fly migration. Using the Rough-legged buzzard as a model species, we confirmed the presence of foxtrot migration and ‘dynamic non-breeding ranges’, driven by environmental factors such as snow cover dynamics. We advocate for accurate representation of dynamic ranges on maps and emphasize the need to consider range dynamics when assessing species conservation status. Our findings underscore the importance of understanding complex migratory behaviors in the face of environmental change, facilitated by advancements in tracking technologies. This knowledge is crucial for effective conservation strategies amid ongoing global environmental challenges.

### Competing Interest Statement

The authors have declared no competing interest.

Quick-quick-slow: the foxtrot migration and dynamic non-breeding range

人新世における鳥類個体群の保護-非繁殖期の移動の重要性


人新世における鳥類個体群の保護: 非繁殖期の移動の重要性
