Ecological Research最新文献

Continental plastic production is on the rise, making these materials significant pollutants with a growing recognition of their impact on agricultural environments. The aim of this study was to provide information about the abundance of plastics in an agricultural environment around the town of Sagunto (Valencia, eastern Spain) and on the use of plastics by the great tit (Parus major), a breeding species in these agricultural areas. Environmental plastic samples were collected using the quadrat method, applied randomly across the study area. Sixty-four samples were collected. Data on the great tit were collected from 35 successful nests, which were gathered after the chicks had fledged. Our results show that 65.6% of the environmental samples contain plastics. From the abundance per square meter, we estimated a density of 18,750 plastic pieces per hectare at the studied agricultural ecosystem. Among the 19 nests containing plastics (54.3%), 556 plastic pieces were found, with the number of pieces per nest ranging from 1 to 153 (mean = 12 ± 1.28; N = 35). Furthermore, the presence of a nearby landfill in Sagunto showed no correlation with the abundance of plastics in either the environment or the nests. This suggests that plastic abundance depends on very local sources, which in this case might be the consequence of farmers and laborers not removing the plastics after use. The great tit selects filament plastics and the colors black and red to incorporate into their nests.

The relationship between organism size and abundance, or population density, has been well characterized by a scaling relationship, with different studies reporting a range of scaling exponents. Various mechanistic explanations have been put forth, more recently leveraging metabolic scaling, but there is still considerable debate about the value of exponents. In this paper, I take a phenomenological approach and use dimensional analysis to address the determinants of organism abundance. By considering four variables—energy input, body size, length, and time—a scaling law for organism abundance as a function of body size emerges, most parsimoniously with an exponent of −1. I also consider how abundance is likely to scale with variables with dimensions of length and time: velocity, acceleration, variance, and covariance. Different scaling exponents for the abundance–body size scaling relationship, including −3/4, can easily be obtained by considering life history components or interactions with the abiotic environment.

Community ecologists often consider their research approaches as either process-oriented or pattern-oriented, which has frequently sparked controversy over the superiority or inferiority of each approach. Here, we argue the ambiguity in the distinction between pattern- and process-oriented approaches by reviewing previous studies. We then highlight three factors—interest, methods, and significance—that influence researchers' perceptions and evaluation of research approaches. This examination reveals the subjectivity inherent in classifying studies. Furthermore, we emphasize the complementary nature of pattern- and process-oriented perspectives in understanding ecological communities. We advocate a scientific culture that embraces diverse research approaches and acknowledges the various levels of generality required to address complex ecological issues. Ultimately, fostering an environment where ecologists with diverse approaches and perspectives collaborate constructively, rather than compete antagonistically, is essential for advancing community ecology.

The initial community assembly of the gut microbiome during infancy significantly influences its development over time. Strains of the genus Bifidobacterium are some of the early colonizers in the infant gut and a commonly used probiotic taxon, but their colonization success varies significantly by situation. This review explores the importance of ecological processes underlying the community establishment of Bifidobacterium strains in the gut by focusing on the potential roles of dispersal, drift, selection, and diversification. We highlight the role of maternal sources in microbial dispersal at birth and discuss the possible consequences of random changes to relative abundances caused by ecological drift. Selective pressures exerted by dietary components, particularly human milk oligosaccharides (HMOs) in breastmilk, can also influence community structure. Diversification enhances genetic variability and enables bifidobacteria to adapt to selective pressures. However, these processes interact with each other, and predicting the colonization success of bifidobacteria is challenging. Here, we propose that considering the balance between stochastic and deterministic processes can help refine strategies for promoting bifidobacterial colonization. When stochastic processes dominate during the initial stages of community assembly, early arrival can help bifidobacteria occupy open niches. On the other hand, once the gut microbiome reaches stability during the later stages of community assembly, deterministic factors become more prominent. In such cases, adding appropriate prebiotics may be necessary to provide a selective advantage. By integrating this framework, we suggest that future research consider how ecological processes affect the colonization success and abundance patterns of Bifidobacterium strains in the infant gut.

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.