Temporal Niche Research Articles

Stratified activity: Vertical partitioning of the diel cycle by rainforest mammals in Borneo

AbstractAnimal activity is driven by the environmental conditions and physical structure of a habitat, and the need to interact with, or avoid, other animals. Knowledge of the proportion of the 24‐hour cycle spent active (activity level), and the time/s of day in which activity is concentrated (activity pattern), informs our understanding of species' ecology and community dynamics. In multidimensional habitats such as tropical rainforests, arboreal (canopy‐dwelling) taxa comprise up to three‐quarters of vertebrate assemblages; yet, wildlife surveys are typically limited to ground level. Terrestrial‐only sampling can result in activity metrics that do not take account of species' full use of horizontal and vertical habitat space. We paired ground‐ and canopy‐level camera traps to characterize mammal activity across vertical strata in Borneo. Additionally, we sampled unlogged and recovering‐logged rainforest to evaluate whether this activity was impacted by logging. Activity across vertical strata varied substantially among 37 species. Arboreal mammals were predominantly nocturnal or diurnal but never cathemeral, terrestrial mammals were mostly nocturnal or cathemeral, and semi‐arboreal mammals appeared to fill the temporal niches under‐utilized by other groups. Differences in activity between unlogged and recovering‐logged forest were minimal, with 92% of species found in both forest types retaining the same activity pattern. Our study demonstrates that the inclusion of canopy‐based sampling provides much greater insights into overall rainforest mammal activity than terrestrial sampling alone. Our results suggest that the varying opportunities and constraints of each stratum act in concert to influence the diel patterns of tropical mammals.Abstract in Malay is available with online material.

The spatial and temporal displacement of native species by domestic dogs

Domestic dogs have been predicted to be a high risk to 10 % of mammal and 11 % of bird species across mainland Southeast Asia. Within Thailand their population is estimated at over 12 million and 80 % live in rural areas where they adopt a free-ranging lifestyle. This lifestyle enables them to enter protected forests without restrictions. To access the spatial and temporal impacts domestic dogs have on local wildlife a two-year camera trap study was undertaken in a fragmented forest complex in Northern Thailand. Co-occurrence modelling was used to estimate the impacts of domestic dogs on a native predator (golden jackal) and prey (green peafowl) specie’s occurrence probability. Temporal segregation was accessed using activity pattern overlaps and compared to Huai Kha Khaeng, a more protected and unfragmented forest complex. Although the results from the co-occurrence models did not find any spatial segregation, it was found that temporal avoidance was occurring in the protected areas with domestic dogs and golden jackal having a clear temporal niche, this temporal separation was lessened in the unfragmented forest. Additionally, over 3x more humans were independently photographed than any other species and 2.5x more domestic dogs were independently photographed than golden jackal in the fragmented protected areas. Ultimately, working in partnership with the local community on approaches that will reduce domestic dogs presence in the forest is essential along with a stringent population management plan in order to lower the number of free-ranging dogs in the area.

The genomic basis of temporal niche evolution in a diurnal rodent

Patterns of diel activity-how animals allocate their activity throughout the 24-h daily cycle-play key roles in shaping the internal physiology of an animal and its relationship with the external environment.1,2,3,4,5 Although shifts in diel activity patterns have occurred numerous times over the course of vertebrate evolution,6 the genomic correlates of such transitions remain unknown. Here, we use the African striped mouse (Rhabdomys pumilio), a species that transitioned from the ancestrally nocturnal diel niche of its close relatives to a diurnal one,7,8,9,10,11 to define patterns of naturally occurring molecular variation in diel niche traits. First, to facilitate genomic analyses, we generate a chromosome-level genome assembly of the striped mouse. Next, using transcriptomics, we show that the switch to daytime activity in this species is associated with a realignment of daily rhythms in peripheral tissues with respect to the light:dark cycle and the central circadian clock. To uncover selection pressures associated with this temporal niche shift, we perform comparative genomic analyses with closely related rodent species and find evidence of relaxation of purifying selection on striped mouse genes in the rod phototransduction pathway. In agreement with this, electroretinogram measurements demonstrate that striped mice have functional differences in dim-light visual responses compared with nocturnal rodents. Taken together, our results show that striped mice have undergone a drastic change in circadian organization and provide evidence that the visual system has been a major target of selection as this species transitioned to a novel temporal niche.

Topcats and underdogs: intraguild interactions among three apex carnivores across Asia's forestscapes.

Intraguild interactions among carnivores have long held the fascination of ecologists. Ranging from competition to facilitation and coexistence, these interactions and their complex interplay influence everything from species persistence to ecosystem functioning. Yet, the patterns and pathways of such interactions are far from understood in tropical forest systems, particularly across countries in the Global South. Here, we examined the determinants and consequences of competitive interactions between dholes Cuon alpinus and the two large felids (leopards Panthera pardus and tigers Panthera tigris) with which they most commonly co-occur across Asia. Using a combination of traditional and novel data sources (N = 118), we integrate information from spatial, temporal, and dietary niche dimensions. These three species have faced catastrophic declines in their extent of co-occurrence over the past century; most of their source populations are now confined to Protected Areas. Analysis of dyadic interactions between species pairs showed a clear social hierarchy. Tigers were dominant over dholes, although pack strength in dholes helped ameliorate some of these effects; leopards were subordinate to dholes. Population-level spatio-temporal interactions assessed at 25 locations across Asia did not show a clear pattern of overlap or avoidance between species pairs. Diet-profile assessments indicated that wild ungulate biomass consumption by tigers was highest, while leopards consumed more primate and livestock prey as compared to their co-predators. In terms of prey offtake (ratio of wild prey biomass consumed to biomass available), the three species together harvested 0.4-30.2% of available prey, with the highest offtake recorded from the location where the carnivores reach very high densities. When re-examined in the context of prey availability and offtake, locations with low wild prey availability showed spatial avoidance and temporal overlap among the carnivore pairs, and locations with high wild prey availability showed spatial overlap and temporal segregation. Based on these observations, we make predictions for 40 Protected Areas in India where temporally synchronous estimates of predator and prey densities are available. We expect that low prey availability will lead to higher competition, and in extreme cases, to the complete exclusion of one or more species. In Protected Areas with high prey availability, we expect intraguild coexistence and conspecific competition among carnivores, with spill-over to forest-edge habitats and subsequent prey-switching to livestock. We stress that dhole-leopard-tiger co-occurrence across their range is facilitated through an intricate yet fragile balance between prey availability, and intraguild and conspecific competition. Data gaps and limitations notwithstanding, our study shows how insights from fundamental ecology can be of immense utility for applied aspects like large predator conservation and management of human-carnivore interactions. Our findings also highlight potential avenues for future research on tropical carnivores that can broaden current understanding of intraguild competition in forest systems of Asia and beyond.

Disentangling Exploitative and Interference Competition on Forest Dwelling Salamanders.

Exploitative competition and interference competition differ in the way access to resources is modulated by a competitor. Exploitative competition implies resource depletion and usually produces spatial segregation, while interference competition is independent from resource availability and can result in temporal niche partitioning. Our aim is to infer the presence of spatial or temporal niche partitioning on a two-species system of terrestrial salamanders in Northern Italy: Speleomantes strinatii and Salamandrina perspicillata. We conducted 3 repeated surveys on 26 plots in spring 2018, on a sampling site where both species are present. We modelled count data with N-mixture models accounting for directional interactions on both abundance and detection process. In this way we were able to disentangle the effect of competitive interaction on the spatial scale, i.e., local abundance, and from the temporal scale, i.e., surface activity. We found strong evidence supporting the presence of temporal niche partitioning, consistent with interference competition. At the same time, no evidence of spatial segregation has been observed.

Phytophthora, Nothophytophthora and Halophytophthora diversity in rivers, streams and riparian alder ecosystems of Central Europe

Waterways are ideal pathways for Phytophthora dispersal and potential introduction to terrestrial ecosystems. While many Phytophthora species from phylogenetic clades 6, 9 and 10 are predominant oomycetes in watercourses due to their adaptation to a lifestyle as saprotrophs and opportunistic pathogens of riparian plants, species from clades 2, 7 and 8 are predominantly soil- or airborne using aquatic habitats as temporal niches for spreading and invading terrestrial sites along the watercourses. In contrast to forest ecosystems, knowledge of Phytophthora diversity in watercourses in Central Europe is limited. Between 2014 and 2019 extensive surveys of streams and rivers were undertaken across Austria, in South Moravia, Czech Republic and Žilina province, Slovakia to unveil the diversity and distribution of Phytophthora and related oomycetes. In addition, in Austria riparian forests of black alder (Alnus glutinosa) and grey alder (A. incana) in lowlands and in the Alps were examined. A variety of Phytophthora species from clades 2, 6, 7, 8, 9 and 10 were isolated, with clade 6 species showing the widest distribution and abundance. Furthermore, interspecific clade 6 hybrids and other oomycetes such as Halophytophthora fluviatilis and undescribed Nothophytophthora spp. were also obtained. In riparian alders, symptoms of Phytophthora infections were associated with species from the P. × alni complex and P. plurivora. Phytophthora plurivora was most common in alder stands whereas P. uniformis was the oomycete species occurring at the highest altitude in alpine riparian areas.

Overlap in habitat use and activity patterns between sika deer (Cervus nippon) and Japanese serows (Capricornis crispus) in subalpine habitats: exploitative competition rather than direct interference?

Examining multiple niche relationships, such as habitat use and activity patterns, between sympatric species contributes to an understanding of the mechanisms of coexistence and competition. Sika deer ( Cervus nippon Temminck, 1838) and Japanese serows ( Capricornis crispus (Temminck, 1836)) often show different habitat use, and diversity in vegetation and topography seems to facilitate their coexistence. Conversely, their habitat use may overlap in areas with low-diversity habitats; however, this remains unstudied. Moreover, whether they spatiotemporally avoid each other to reduce direct interference is unclear. We examined the fine-scale patterns of habitat use and activity of deer and serows in the subalpine forests of Mount Fuji, which have low-diversity habitats, using camera trapping data over 3 years. Deer and serow habitat niches largely overlapped, especially in summer (92%–94%) and autumn (89%–91%), suggesting that low-diversity habitats facilitate overlapping habitat use. Both species selected areas frequently used by the other during spring to autumn and their temporal niches largely overlapped, especially in summer (88%) and autumn (83%), suggesting that they do not spatiotemporally avoid each other (i.e., there is no direct interference). Rapid range expansion of deer into these subalpine habitats may exclude native serows through resource exploitative competition rather than interference competition.

Spatio-temporal distribution and overlap of Naemorhedus griseus and Capricornis milneedwardsii in Gongga Mountain, Sichuan, China.

Clarifying the distribution pattern and overlapping relationship of sympatric relative species in the spatio-temporal niche is important for our understanding of the behavioral relationship between species and the integrated management of multi-species habitats. Based on the infrared camera monitoring data from 2012 to 2021, we investigted the spatio-temporal distribution characteristics of the national secondary-class key protected animals Naemorhedus griseus and Capricornis milneedwardsii in the Gongga Mountain National Nature Reserve, Sichuan Province. We analyzed the distribution of N. griseuss and C. milneedwardsiis in the reserve using the MaxEnt model, based on 72 and 108 occurrence data of the two species, respectively, obtained by infrared cameras from 2016 to 2021, combined with 12 environmental factors potentially affecting their spatial distribution. Then, based on 1312 occurrence data of N. griseus and 1889 occurrence data of C. milneedwardsii collected by infrared camera from 2012 to 2021, we estimated their daily activity rhythms by using the kernel density estimation to understand the distribution pattern and overlap of the two species in the temporal niche. The results showed that the area of suitable habitats for N. griseus and C. milneedwardsii was 731.95 km2 and 1220.46 km2, respectively. The overlapping area was 697.17 km2. The main environmental factors had similar effects on the habitat selection of the two species. The daily activity of both species peaked in the early morning and evening. The utilization of the interval and intensity of the morning and evening time periods were different for the two species. The morning and evening activity peaks of C. milneedwardsii were earlier and later, respectively, than that of N. griseus. C. milneedwardsii had a higher utilization intensity during the nocturnal period. In general, high degree of spatial overlap and low degree of overlap in the temporal niche dimension contribute to the long-term coexistence of the two species.

Carnivore coexistence in Chicago: niche partitioning of coyotes and red foxes

Mesopredators including coyotes (Canis latrans) and red foxes (Vulpes vulpes) often co-occur in urban environments, but how niche partitioning facilitates their coexistence remains unclear. Highly urbanized areas can be spatial refuges for smaller mesopredators (i.e., spatial human shield effect), however these species also may coexist through temporal niche partitioning. We used camera traps (n = 110 sites) across an urbanization gradient in Chicago to examine coyote-fox interactions from 2011 to 2018. We analyzed spatial partitioning through multi-season occupancy models and structural equation modeling (SEM), and quantified temporal overlap between canids and with humans. Coyotes most often occurred in natural areas, and urbanization reduced their colonization rates and increased their extinction rates. Initial occupancy for red foxes was negatively impacted by urbanization, but their extinction rates depended on a surprising interaction between coyotes and humans. When coyotes were rare, fox extinction was related positively to human activity; but when coyotes were more common, fox extinction was related negatively to human activity. This outcome may reflect a human shield effect at a within-site scale. The SEM further supported the negative impact of urbanization on both canids, and lack of an effect of coyotes on the distribution of foxes. Diel activity of coyotes and red foxes indicated temporal niche partitioning intensified at more urbanized sites. Our results suggest the spatial human shield effect is not operating across sites in Chicago. Instead, coyotes and red foxes may share green spaces, especially in highly urbanized areas, where species coexistence is promoted by temporal niche partitioning.

Spatial and temporal niche separation of methanomassiliicoccales phylotypes in temperate fens.

The hydrogen-dependent and methylotrophic order Methanomassiliicoccales consists of the families Methanomethylophilaceae and Methanomassiliicoccaceae. While Methanomethylophilaceae are comparatively well studied, there is a lack of knowledge on Methanomassiliicoccaceae. In this 16S rRNA gene amplicon sequencing based study we investigated the temporal and spatial dynamics of the Methanomassiliicoccales in drained and rewetted sites of three common temperate fen peatlands. A 2.5-year-monitoring of the fen microbiome composition in three peat depths revealed a dynamic methanogen and Methanomassiliicoccales composition across space and time. Four Methanomassiliicoccales phylotypes were found and they were differentially distributed between the fen types. The wetland cluster phylotype was omnipresent and dominant in abundance in all sites along all depths. The Methanomassiliicoccales phylotype was highly abundant in topsoil while the AB364942 phylotype was exclusively found in deeper regions of the rewetted percolation fen. The phylotype affiliated with Methanomassiliicoccales strain U3.2.1 was only detected in the rewetted percolation fen. We discussed the distribution of the four phylotypes with implications to their ecophysiology, where oxygen tolerance and substrate spectrum might play major roles. In conclusion, the Methanomassiliicoccales are widespread and do account for a significant proportion of methanogens, which might suggest their importance for methane emissions from peatlands.

A review of caracal and jungle cat diets across their geographical ranges during 1842-2021.

Co-occurring carnivore species that are phylogenetically related or of similar size, morphology, and ecological needs often reduce competition by partitioning shared resources through temporal, spatial, and dietary niche segregation via behavioral adaptations. Caracals (Caracal caracal) and jungle cats (Felis chaus) co-occur in portions of their geographical ranges and are expected to display resource segregation in these ranges. We compiled scat, stomach content, and prey remains found data from published and unpublished sources to summarize information on the diets of caracals and jungle cats across their geographical ranges during 1842-2021. We obtained 63 sources from 26 countries in Europe, Asia, and Africa, in which caracal diet included 151 species while jungle cat diet included 61 species. We found that caracals and jungle cats did not exhibit dietary niche partitioning and had greater dietary similarities in areas of range overlap. We also found that caracals consumed more diverse prey species including prey with greater average body mass compared to jungle cats. Our results suggest that greater prey diversity in areas of range overlap, caracal predation on wide range of prey, and opportunistic feeding behavior that facilitates consumption of more diverse prey species compared to jungle cats, may facilitate co-occurrence between these two felid species.

Combined effects of light pollution and vegetation height on behavior and body weight in a nocturnal rodent

At a global scale, organisms are under threat due to various kinds of environmental changes, such as artificial light at night (ALAN), noise, climatic change and vegetation destruction. Usually, these changes co-vary in time and space and may take effect simultaneously. Although impacts of ALAN on biological processes have been well documented, our knowledge on the combined effects of ALAN and other environmental changes on animals remains limited. In this study, we conducted field experiments in semi-natural enclosures to explore the combined effects of ALAN and vegetation height on foraging behavior, vigilance, activity patterns and body weight in dwarf striped hamsters (Cricetulus barabensis), a nocturnal rodent widely distributed in East Asia. We find that ALAN and vegetation height affected different aspects of behavior. ALAN negatively affected search speed and positively affected handling speed, while vegetation height negatively affected giving-up density and positively affected body weight. ALAN and vegetation height also additively shaped total time spent in a food patch. No significant interactive effect of ALAN and vegetation height was detected. C. barabensis exposed to ALAN and short vegetation suffered a significant loss in body weight, and possessed a much narrower temporal niche (i.e. initiated activity later but became inactive earlier) than those under other combinations of treatments. The observed behavioral responses to ALAN and changes in vegetation height may bring fitness consequences, as well as further changes in structure and functioning of local ecosystems.

Species coexistence and niche interaction between sympatric giant panda and Chinese red panda: A spatiotemporal approach.

The giant panda (Ailuropoda melanoleuca) and the Chinese red panda (Ailurus styani) are distributed in the same region in the mountain forest ecosystem on the eastern edge of the Qinghai Tibet Plateau and share the same food sources. In order to understand how sympatric giant pandas and Chinese red pandas maintain interspecific relationships to achieve stable coexistence, we used species distribution models and diurnal activity rhythms to analyze the spatial and temporal niche characteristics of giant pandas and Chinese red pandas in the Daxiangling Mountain system based on 187 camera traps data. The results show that: (1) In the Daxiangling Mountains, the total area of suitable habitats for giant pandas and Chinese red pandas is 717.61 km2 and 730.00 km2, respectively, accounting for 17.78% and 18.25%, respectively, of the study area. (2) The top five environmental factors contributing to the model of giant panda and Chinese red panda are precipitation seasonality, temperature seasonality, distance to the road, and elevation and vegetation type. (3) The total overlapping area of suitable habitats for giant pandas and Chinese red pandas is 342.23 km2, of which the overlapping area of highly suitable habitats is 98.91 km2. The overlapping index of suitable habitats is 0.472, and the overlapping index of highly suitable habitats is 0.348, which indicates that the two achieve spatial niches are separated to achieve stable coexistence. (4) The overlapping index of the daily activity rhythm of giant panda and Chinese red panda is 0.87, which is significantly different (p < .05). The existence of Chinese red panda will significantly affect the daily activity rhythm of giant panda (p < .001). This research can provide scientific reference for the researches about population and habitat protection of giant pandas and Chinese red pandas, so as to understand the driving mechanism of resource allocation and population dynamics of sympatric species.

Multiscale phenological niches of seed fall in diverse Amazonian plant communities.

Phenology has long been hypothesized as an avenue for niche partitioning or interspecific facilitation, both promoting species coexistence. Tropical plant communities exhibit striking diversity in reproductive phenology, but many are also noted for large synchronous reproductive events. Here we study whether the phenology of seed fall in such communities is nonrandom, the temporal scales of phenological patterns, and ecological factors that drive reproductive phenology. We applied multivariate wavelet analysis to test for phenological synchrony versus compensatory dynamics (i.e., antisynchronous patterns where one species' decline is compensated by the rise of another) among species and across temporal scales. We used data from long-term seed rain monitoring of hyperdiverse plant communities in the western Amazon. We found significant synchronous whole-community phenology at multiple timescales, consistent with shared environmental responses or positive interactions among species. We also observed both compensatory and synchronous phenology within groups of species (confamilials) likely to share traits and seed dispersal mechanisms. Wind-dispersed species exhibited significant synchrony at ~6-month scales, suggesting these species might share phenological niches to match the seasonality of wind. Our results suggest that community phenology is shaped by shared environmental responses but that the diversity of tropical plant phenology may partly result from temporal niche partitioning. The scale-specificity and time-localized nature of community phenology patterns highlights the importance of multiple and shifting drivers of phenology.

Temporal Activity Patterns of Sympatric Species in the Temperate Coniferous Forests of the Eastern Qinghai-Tibet Plateau.

Temporal niche partitioning is an important strategy for sympatric species or populations when utilizing limited resources while minimizing competition. Different resource availability across seasons may also influence the intensity of competition, resulting in a varied temporal niche partitioning pattern between species. These competitive interactions are important drivers for the formation of biodiversity patterns and species coexistence on the eastern Qinghai-Tibet Plateau. To clarify these interspecies relationships among sympatric species, we carried out a camera trap survey from 2017 to 2020. We deployed 60 camera traps in the temperate coniferous forests of the eastern Qinghai-Tibet Plateau. We analyzed the daily activity patterns of birds and mammals to reveal the temporal niches and seasonal relationships among the species-specific activity rhythms. The results are summarized as follows: (1) Eight major species, including mammals and birds, have different temporal peak activity rhythms to reduce intense competition for resources. (2) The activity rhythm of a species varies seasonally, and the competition among species is more intense in the warm season than in the cold season. (3) Among 15 pairs of competitor species, seven pairs had significantly different coefficients, with higher winter values than summer values, perhaps due to the abundance of resources in summer and the scarcity of resources in winter causing intensified competition. Among the predators and prey, the summertime coefficients were higher than those in winter, perhaps due to the need to replenish energy during the summer breeding season. The main purpose of animals in winter is to survive the harsh environment. Our results provide important information on temporal and interspecies relationships and contribute to a better understanding of species-coexistence mechanisms.

Interplay between strain fitness and transmission frequency determines prevalence of antimicrobial resistance

The steep rise of infections caused by bacteria that are resistant to antimicrobial agents threatens global health. However, the association between antimicrobial use and the prevalence of resistance is not straightforward. Therefore, it is necessary to quantify the importance of additional factors that affect this relationship. We theoretically explore how the prevalence of resistance is affected by the combination of three factors: antimicrobial use, bacterial transmission, and fitness cost of resistance. We present a model that combines within-host, between-hosts and between-populations dynamics, built upon the competitive Lotka-Volterra equations. We developed the model in a manner that allows future experimental validation of the findings with single isolates in the laboratory. Each host may carry two strains (susceptible and resistant) that represent the host’s commensal microbiome and are not the target of the antimicrobial treatment. The model simulates a population of hosts who are treated periodically with antibiotics and transmit bacteria to each other. We show that bacterial transmission results in strain co-existence. Transmission disseminates resistant bacteria in the population, increasing the levels of resistance. Counterintuitively, when the cost of resistance is low, high transmission frequencies reduce resistance prevalence. Transmission between host populations leads to more similar resistance levels, increasing the susceptibility of the population with higher antimicrobial use. Overall, our results indicate that the interplay between bacterial transmission and strain fitness affects the prevalence of resistance in a non-linear way. We then place our results within the context of ecological theory, particularly on temporal niche partitioning and metapopulation rescue, and we formulate testable experimental predictions for future research.

Golden-bellied mangabeys (Cercocebus chrysogaster) exhibit a larger home range and longer travel distances than those of bonobos (Pan paniscus) at LuiKotale, Democratic Republic of the Congo.

Primate ranging behavior is associated with numerous social and ecological correlates. Interspecific comparisons of ranging behavior can therefore provide insight into the socio-ecological conditions that characterize a species' niche within its community. We provide the first description of ranging behavior in golden-bellied mangabeys (Cercocebus chrysogaster), using sympatric bonobos (Pan paniscus) as a comparison. Over 6 months, we recorded GPS tracks at 1- and 5-min intervals from one habituated golden-bellied mangabey group and two habituated bonobo communities at LuiKotale, central Democratic Republic of the Congo. We compared estimates of home range size, time spent at different elevations, and hourly travel distances between species. We modeled daily travel distances against total monthly rainfall to investigate seasonal variation in daily ranging. The golden-bellied mangabey home range was similarly sized or larger than each of the two bonobo communities at LuiKotale across estimation methods. Mangabeys visited more of their range per day and spent more time in terra firma forest and less time in swamps than bonobos. Mangabeys traveled significantly farther per day and during midday hours than bonobos, but travel distances did not relate to monthly rainfall in either species. Golden-bellied mangabeys exhibited wide daily ranging behavior that more closely resembled that of sympatric bonobos than other Cercocebus species. Large homes ranges in mangabeys are likely influenced by food availability in terra firma forest, especially as groups appear to travel long distances between fruit trees and terrestrial food patches. Maximizing daytime activity may help mangabeys avoid competition from heterospecifics and indicates temporal niche partitioning in this primate community.

Butterfly foraging is remarkably synchronous in an experimental tropical macrocosm.

Diel patterns in foraging activity are dictated by a combination of abiotic, biotic and endogenous limits. Understanding these limits is important for insects because ectotherm taxa will respond more pronouncedly to ongoing climatic change, potentially affecting crucial ecosystem services. We leverage an experimental macrocosm, the Montreal Insectarium Grand Vivarium, to test the importance of endogenous mechanisms in determining temporal patterns in foraging activity of butterflies. Specifically, we assessed the degree of temporal niche partitioning among 24 butterfly species originating from the Earth's tropics within controlled environmental conditions. We found strong niche overlap, with the frequency of foraging events peaking around solar noon for 96% of the species assessed. Our models suggest that this result was not due to the extent of cloud cover, which affects radiational heating and thus limits body temperature in butterflies. Together, these findings suggest that an endogenous mechanism evolved to regulate the timing of butterfly foraging activity within suitable environmental conditions. Understanding similar mechanisms will be crucial to forecast the effects of climate change on insects, and thus on the many ecosystem services they provide.

Niche Analysis of the Main Fish in the Lhasa River Basin

The Lhasa River is one of the five tributaries of the Yarlung Zangbo River. It is the main industrial, agricultural and animal husbandry area in Tibet. It plays an important ecological security barrier role in regulating regional climate and maintaining biodiversity. In order to understand the resource utilization ability and relationship of fish in Lhasa River, and provide basic data for the protection and sustainable utilization of fish diversity in Lhasa River, the fishery resources in September 2019 (autumn), June 2020 (summer), November 2020 (winter) and March 2021 (spring) were investigated for the first time. The main fish in the catch were determined by the Index of Relative Importance (IRI). Shannon index and Pianka’s index were used to analyze the niche breadth and overlap values of the main fish caught in Lhasa River Basin from three dimensions of time, space and space–time. The results show that a total of 1399 fish of 3 orders and 4 families were collected. Among them, there is one dominant species, Schizopygopsis younghusbandi, and five common species, Schizothorax waltoni, Schizothorax oconnori, Ptychobarbus dipogon, Triplophysa stenura and Carassius auratus. The spatial–temporal niche breadth ranges from 1.395 to 3.628. They are Schizopygopsis younghusbandi, Carassius auratus, Ptychobarbus dipogon, Schizothorax oconnori, Triplophysa stenura and Schizothorax waltoni in a declining order. The temporal niche breadth is generally small, indicating that the survival activities of the main fish are greatly affected by seasonal changes. The fluctuation range of spatial–temporal overlap value is 0–0.535, and only 20% of the total logarithm is meaningful. The species pairs with temporal niche overlap values exceeding 0.300 reached 80%, while the spatial niche overlap value is generally low. The results show that the spatial and temporal distributions of the main fish in Lhasa River were quite different, and the spatial and temporal niche overlap value of the relationship between species is obviously affected by the change in spatial distribution. This demonstrates that the competition relationship and intensity of the main fish are quite different in different spatial positions.

Diverse flower-visiting responses among pollinators to multiple weather variables in buckwheat pollination

Response diversity to environmental change among species is important for the maintenance of ecosystem services, but response diversity to changes in multiple environmental parameters is largely unexplored. Here, we examined how insect visitations to buckwheat flowers differ among species groups in response to changes in multiple weather variables and landscape structures. We found differences in responses to changes in weather conditions among insect taxonomic groups visiting buckwheat flowers. Beetles, butterflies, and wasps were more active in sunny and/or high-temperature conditions, whereas ants and non-syrphid flies showed the opposite pattern. When looking closely, the different response pattern among insect groups was itself shown to be different from one weather variable to another. For instance, large insects were responsive to temperatures more than small insects while smaller insects were responsive to sunshine duration more than large insects. Furthermore, responses to weather conditions differed between large and small insects, which agreed with the expectation that optimal temperature for insect activity depends on body size. Responses to spatial variables also differed; large insects were more abundant in fields with surrounding forests and mosaic habitats, whereas small insects were not. We suggest that response diversity at multiple spatial and temporal niche dimensions should be a focus of future studies of the biodiversity–ecosystem service relationships.