Ecological Research最新文献

Industrial oil palm plantations are a major driver of biodiversity loss in Southeast Asia, alongside other industries like pulpwood production and logging activities that expedite habitat fragmentation and destruction. Despite this, some native species are highly adaptable within these environments. Our study investigates the space use of leopard cats (Prionailurus javanensis) within oil palm plantations adjacent to degraded forest fragments in the Kinabatangan floodplain, Sabah, Malaysian Borneo. From March to September 2020, we captured and collared four male cats with Global Positioning System collars, accumulating a total of 13,206 successful locational points. We estimated the home ranges using the Minimum Convex Polygon (MCP) and Adaptive Localized Convex Hull (a-LoCoH) methods. The average home ranges were 8.60 km² ± 1.98 (±SD) [95% MCP] and 5.39 km² ± 1.23 [95% a-LoCoH], with corresponding core areas of 2.55 km² ± 0.99 (±SD) [50% MCP] and 1.05 km² ± 0.30 [50% a-LoCoH]. The home ranges of male leopard cats overlapped (7% to 28%), while core areas remained exclusive. Despite significant variations in individual habitat use, these cats were detected more frequently in oil palm habitat, occupying 80.89% of their home range and 78.38% of core area. These cats relied more on buffer zones contiguous to plantation area rather than adjacent secondary forests, highlighting the importance of preserving High Conservation Value (HCV) forests.

Studies of host–parasitoid dynamics have traditionally focused on parasitic insects, but nematodes occasionally show levels of parasitism comparable to those of flies and wasps. Because parasitic insects and nematodes differ greatly in phylogeny and ecology, the biotic and abiotic factors that affect parasitism rates in these taxa are expected to be quite different. We aimed to determine how the parasitism rates of tachinid flies and mermithid nematodes on the endangered butterfly Reverdin's Blue (Plebejus argyrognomon) were influenced by attendant ants and abiotic conditions. We found that parasitism by mermithid nematodes increased, while parasitism by tachinids decreased, with an increasing number of precipitation days. Ant species effective in defending against tachinid flies differed from those effective in defense against mermithid nematodes, which may be related to the degree of overlap in the daily activity patterns of parasitoids and ants. In addition, higher vegetation increased the parasitism rates of both tachinids and mermithids. This may reflect the creation of a more humid microclimate for mermithids and greater resource availability for tachinids in complex vegetation structures. The sum of the two parasitism rates showed a hump-shaped relationship with the number of precipitation days. Further clarification of the parasitism mechanisms in the two groups of parasitoids will be important for predicting how host populations will respond to future climate change.

In response to climate change, species may shift their ranges toward the poles, alter their phenotypes, change their physiological resilience to rapidly rising temperatures, or some combination of the three. Physiological resilience is particularly important for species that are unable to migrate. For ectotherms, metabolic rates adjust to environmental temperatures; however, the degree to which their metabolism can adapt to temperature change is not well studied. Assessing invertebrate resilience to a rapidly warming environment is crucial for gauging their ability to adapt to climate change. Resilience to the metabolic stress associated with rapid temperature shifts may be assessed by determining how flexible the metabolic rate is at different temperatures. Here we examine the degree of metabolic plasticity (assessed via stable carbon isotope turnover proxy) for the adults of two species of invertebrates, the amphipod Gammarus minus and the isopod Caecidotea kenki, at temperatures ranging from 5°C to 18°C over the course of 24 days. Not surprisingly, isotope turnover increased with temperature for both species. The carbon isotopic endmembers were maple leaves (−30.4 ± 0.2‰, N = 20) and corn leaves (−12.2 ± 0.4‰, N = 20). Half-lives were between 60 and 90 days at 5°C and between 20 and 35 days at 18°C. G. minus showed a small but significantly greater variation in metabolic response to elevated temperatures than C. kenki, suggesting that it has a greater potential for successfully adapting to a warming climate.

Large-sized herbivores in cold regions often suffer from deep snow, which sharply increases their physio-behavioral costs. Among such animals, sika deer (Cervus nippon) have recently expanded their distribution into northern mainland Japan, one of the snowiest regions on Earth. In this study, we aimed to reveal the overwintering foraging tactics adopted by sika deer in these regions. We recorded the feeding marks of sedentary deer for 3 years with different snow accumulations by surveying transects established in southwestern Fukushima (total lengths: 145.5, 133.6, and 172.9 km in 2021–2023, respectively) and analyzed the composition and selectivity of food plants. Our key findings are as follows: (1) sedentary deer fed on the branch tips and bark of 112 woody plant species; (2) although the expected species richness of plants consumed by the deer differed only slightly between different snow conditions based on rarefaction/extrapolation analysis, food plant composition varied widely across the years (Bray–Curtis index >0.5 between every pair of years); (3) Manly's selectivity index indicated that the compositions of positively and negatively selected plant species were sensitive to different snow conditions; and (4) deer relied heavily on bark when snow depth increased; specifically, the probability of debarking when deer fed on plants in the heavy snow year was seven times higher than in the light snow year. These findings reveal that sedentary deer adopt euryphagous and opportunistic feeding tactics by switching their dietary composition to readily available foods in response to different snow conditions.

Temporal changes in community composition, known as temporal beta diversity, are a facet of biodiversity change. Macroecological patterns of temporal beta diversity have gained attention due to the recent biodiversity crisis. However, little attention has been paid to how temporal beta diversity differs from spatial beta diversity, and even the most basic neutral dynamics and temporal beta-diversity patterns remain poorly understood. Therefore, this study aimed to reveal the basic properties of temporal beta-diversity under neutral dynamics and to identify how they differ from spatial beta-diversity patterns. A simulation of neutral dynamics was conducted to test the parameter dependency of temporal beta-diversity patterns. Specifically, four fundamental parameters of the neutral model—the fundamental biodiversity number, local community size, mortality rate, and immigration rate—were studied. To describe the form of the simulated temporal distance-decay patterns based on the Bray–Curtis and Sørensen dissimilarity indices, a three-parameter negative exponential function was fitted to each simulated dissimilarity matrix. The negative exponential function was successfully fitted to all the simulated results. The simulated results demonstrated that upper limits exist in the temporal distance-decay patterns; thus, the temporal distance-decay curves saturate before reaching a completely dissimilar state. Additionally, the form of the curve strongly depends on the four parameters of the neutral model. These results, combined with conceptual considerations, suggest that the relationship between local communities and virtual species pools differs between temporal and spatial beta diversity. Specifically, it is hypothesized that the species pool is spatially variable but temporally more constant.

Coastal habitat restoration is an essential component of conservation management, given the dramatic coastal wetland loss on a global scale. In the Five Lakes of Mikata-goko (western Japan), creation and restoration projects for nature-based coastal protection (semi-natural coastal habitats) have recently been implemented and initiated by the Nature Restoration Committee; however, their outcomes in terms of biodiversity have yet to be evaluated. In this study, spatiotemporal changes in macrozoobenthic assemblages were examined to provide insights into coastal habitat restoration using local knowledge (LK). Natural forces (winds and waves) were used to replenish sand along a sand-starved shoreline in the LK-based practice. The restored shallow-water habitat realized seasonally stable species richness and higher annual richness of brackish-water macrozoobenthic assemblages dominated by previously prevalent species, the Shijimi clam (Corbicula japonica) and the nereid polychaeta (Hediste atoka) compared with adjacent deep, unrestored sites. The changes in assemblage structure were likely due to seasonally stable low-salinity (mesohaline) and oxygen-rich conditions (dissolved oxygen concentration >5 mg L⁻¹), owing to the shallow water depth in the restored habitat. The results suggest that the beach nourishment practice partially and successfully mitigated historical habitat loss in the lakes and, hence, can provide suggestions for future mitigation practices of coastal habitat loss in estuaries.

Plateau pikas alter alpine meadow biodiversity and ecosystem functions via foraging, burrowing, and excretion. While plant and soil biodiversity synergistically regulate ecosystem multifunctionality (EMF), their relative contributions under varying pika densities remain unclear. Through a 5-year study on the Tibetan Plateau's eastern edge, we assessed pika disturbance effects on multi-trophic biodiversity (plants, earthworms, ciliates, fungi, bacteria) and EMF (biomass, soil nutrients). Results showed plant diversity exerted stronger EMF control than soil biodiversity across burrow density gradients. At 550 burrows/ha, EMF drivers shifted: soil biodiversity maintained positive correlations in low-density areas, while plant diversity dominated in high-density zones. Structural equation modeling further revealed density-dependent divergence in regulatory pathways—both plant and soil biological diversity showed significant positive correlations with pika density under low-density conditions, but these relationships inverted to negative correlations in high-density environments. In conclusion, plateau pika densities reaching 550 burrows/ha trigger a shift in dominant drivers of EMF. We recommend maintaining populations below this critical threshold to sustain functional gains while prioritizing plant diversity conservation in density-exceeding areas, thereby balancing ecological services and productivity in alpine meadows.

This study investigated seasonal variations in phototrophic biofilm communities at the entrance zone of Petnica Cave. Biofilm samples were collected from seven sampling sites over four seasons. Several parameters were measured at each site, including air temperature, relative humidity, light intensity, substrate temperature, and moisture content of both biofilm-covered and bare substrates, to assess their influence on species composition. Cyanobacteria were the dominant group. According to the redundancy analysis (RDA), coccoid and simple trichal Cyanobacteria predominated in winter, while heterocytous Cyanobacteria were more abundant in summer. Chlorophyta exhibited a relatively even distribution across all seasons. Principal component analysis (PCA) revealed that Cyanobacteria occurrence showed a positive correlation with the moisture content of both the biofilm and the substrate, whereas Chlorophyta demonstrated a negative correlation with these parameters. Despite the presence of core taxa in all seasons, additional taxa appeared seasonally, contributing to increased diversity. These findings highlight the importance of moisture for the composition and resilience of the biofilm and provide insights into the seasonal adaptations of microorganisms in the cave entrance zone ecosystem.

The taxonomic, phylogenetic, and functional beta diversity (BD_tax, BD_phy, and BD_fun, respectively) of flea faunas across host species, in seven continental sections from four continents, was partitioned into species (=flea) and local (=host) contributions. We asked (a) whether the same flea or host species contributed similarly to taxonomic, phylogenetic, and functional beta diversity within each continental section; (b) which flea and host traits drove their contributions to BD_tax, BD_phy, and BD_fun; and (c) whether the effects of these traits on flea and host contributions differed between continental sections. Although different fleas and hosts contributed differently to each beta diversity facet, contributions of the same species to BD_tax, BD_phy, and BD_fun were similar. The heterogeneity between flea faunas, harbored by different host species, was mainly due to the variation in flea species composition, with the distribution of phylogenetic lineages and functional attributes playing lesser roles. The host contributions to BD_phy and BD_fun were driven by phylogenetic and functional similarities between flea species. The relationships between flea traits and their contributions to BD_tax, BD_phy, and BD_fun were weak (if at all), whereas host contributions were mainly associated with the structure of flea faunas in terms of species richness, with the effect of functional host traits being weaker. The main geographic differences in flea and host contributions to BD_tax, BD_phy, and BD_fun were differential associations between these contributions and flea and host functional traits. We concluded that the between-host heterogeneity of flea faunas was driven by the interplay of ecological and historical processes.

Conifers generally exhibit narrow, deep crowns, whereas broadleaf trees typically form spherical crowns. A widely accepted hypothesis attributes this difference to variations in solar angles: conifers, which prevail in high-latitude regions with lower solar angles, optimize light capture differently than broadleaf trees, which dominate low-latitude areas with higher solar angles. Previous studies have suggested that differences in crown morphology mitigate light competition in mixed forests, facilitating coexistence and enhancing productivity. However, these studies relied on simplified structural models that did not fully account for the physiological constraints of crown morphology or the dynamics of crown competition. In this study, we employed the Spatially Explicit Individual-Based Dynamic Global Vegetation Model to examine the effects of crown morphology on competition dynamics and ecosystem productivity in mixed forests. The model incorporates novel elements: (1) competition for space during canopy expansion, (2) self-pruning due to shading (i.e., lower branch dieback), (3) reductions in crown basal area resulting from self-pruning, and (4) reductions in total leaf area per tree following basal area loss. A 100-year simulation of narrow- and wide-crown saplings with distinct crown morphologies revealed that their relative advantages depended on tree density, planting arrangement, solar angle, and the composition of solar radiation (i.e., direct vs. diffuse light). However, contrary to prior assumptions, negative frequency-dependent selection—expected to promote coexistence—was not observed. Moreover, crown shape diversity did not enhance forest productivity. These findings challenge previous models and suggest that factors beyond crown morphology may drive species coexistence and ecosystem productivity in mixed ecosystems.