Temporal Niche Research Articles

The invasion of Japanese hop (Humulus japonicus) in a restored floodplain forest

Abstract Japanese hop (Humulus japonicus Sieb. & Zucc.) is an emerging invasive plant that has been observed to invade and spread throughout wetlands. As an annual vine, H. japonicus can smother native vegetation, forming dense stands and reducing biodiversity. At a restored floodplain forest in Joslin, Illinois, formerly used as an experimental site to test the effectiveness of different reforestation methods, H. japonicus has invaded stands of the previously dominant invasive, reed canarygrass (Phalaris arundinacea L.). We conducted an observational field study to examine the spatio-temporal dynamics of H. japonicus invasion relative to gradients in canopy cover and species composition. Ten transects, with half the transect extending into and half extending beyond H. japonicus patches, were established in October 2022. Seven quadrats per transect were surveyed for vegetation cover and canopy cover in October 2022, June 2023, and October 2023. Transects were evenly split between forested and open areas based on the reforestation treatments. H. japonicus cover significantly increased from October 2022 to October 2023, which has resulted in a slight decrease and replacement of P. arundinacea across the site. Shade reduced H. japonicus cover, indicating its preference for sunlit conditions. Species richness was higher in forested transects compared to open ones, most likely due to the absence of both P. arundinacea and H. japonicus in shaded transects. Along transects, quadrats that had been invaded by H. japonicus differed in species composition from quadrats that had not been invaded in both October 2022 and October 2023. H. japonicus cover was much lower in June than October, suggesting that temporal niche partitioning may allow P. arundinacea to persist, and indicating that monitoring for H. japonicus should occur late in the growing season. Both invasive species are shade intolerant, suggesting that planting fast-growing trees should be an effective long-term solution for controlling invasion.

Breath-hold capacities and circadian dive rhythmicity shape optimal foraging strategies in a polar marine mammal, the Weddell seal (Leptonychotes weddellii)

Air-breathing vertebrates must balance their response to diel shifts in prey accessibility with physiological thresholds and the need to surface after each dive. Weddell seal (Leptonychotes weddellii) dive behaviors were tracked across the year under rapidly-changing light regimes in the Ross Sea, Antarctica ( ~ 75-77°S). This provides a ‘natural experiment’ with free-living seals experiencing 24-hrs of light (Polar Day), light/dark cycling, and continuous darkness (Polar Night). The Weddell seal’s temporal niche switches from nocturnal diving in the summer to diurnality for the remainder of the year. Rhythmicity in dive efforts (depth, duration, post-dive surface recuperation, bottom time, and exceeding physiologic thresholds) is stronger and more closely circadian during times of the year with light/dark cycling compared with Polar Day or Night. With light/dark cycling, animals also make the most extreme dives (those that far exceed the calculated aerobic dive limit, cADL) significantly earlier than solar noon. Offsetting the longest dives that require longer surface recuperation times from mid-day allows animals to maximize total dive time under high-light conditions conducive for visual hunting. We identify an optimal foraging strategy to exploit a diel preyscape in a highly-seasonal environment, while balancing tradeoffs imposed by physiological thresholds in a diving mammal.

Daily activity rhythm of sympatric ungulate species in Fanjingshan Reserve, China

Sympatric species inhabiting similar ecological niches can coexist by partitioning aspects of available ecological resources, such as temporal, spatial, and nutritional niches. Ungulates often coexist in the same habitat, resulting in temporal partitioning and divergence in foraging strategies and spatial utilization. To understand the temporal patterns of ecological differentiation and coexistence mechanisms among sympatric ungulates, we analyzed the monitoring data in Fanjingshan National Nature Reserve, Guizhou, China, from 2017 to 2022. Kernel density estimation was used to scrutinize disparities in diurnal activity patterns among four ungulates [tufted deer (Elaphodus cephalophus), Reeves' muntjac (Muntiacus reevesi), wild boar (Sus scrofa), and mainland serow (Capricornis milneedwardsii)] as well as the interspecies variances during different seasons, at diverse altitudes, and between breeding and non-breeding periods. Daily activity patterns differed significantly among four species, with those of tufted deer, Reeves' muntjac, and wild boar affected significantly by season and breeding cycle. In addition, the daily activity rhythms of four species were affected by altitude. Thus, the daily activity rhythms of these ungulates were resulted from a combination of environmental factors and interspecific competitive interactions, as well as the reproductive cycle of each species. Our results provided a scientific reference for the effective management of wildlife and forest ecosystems, and we suggest that knowledge of temporal dynamics should be integrated into conservation planning for these sympatric species.

Increased Evolutionary Rate in the Z chromosome of Sympatric and Allopatric Species of Morpho Butterflies.

Divergent evolution of genomes among closely related species is shaped by both neutral processes and ecological forces, such as local adaptation and reinforcement. These factors can drive accelerated evolution of sex chromosomes relative to autosomes. Comparative genomic analyses between allopatric and sympatric species with overlapping or divergent ecological niches offer insights into reinforcement and ecological specialization on genome evolution. In the butterfly genus Morpho, several species coexist in sympatry, with specialization across forest strata and temporal niches. We analyzed the genomes of eight Morpho species, along with previously published genomes of three others, to compare chromosomal rearrangements and signs of positive selection in the Z chromosome vs. autosomes. We found extensive chromosomal rearrangements in Z chromosome, particularly in sympatric species with similar ecological niches, suggesting a role for inversions in restricting gene flow at a postzygotic level. Z-linked genes also exhibited significantly higher dN/dS ratios than autosomal genes across the genus, with pronounced differences in closely related species living in sympatry. Additionally, we examined the evolution of eight circadian clock genes, detecting positive selection in Period, located on the Z chromosome. Our findings suggest that the Z chromosome evolves more rapidly than autosomes, particularly among closely related species, raising questions about its role in prezygotic and postzygotic isolation mechanisms.

Temporal niche partitioning as a potential mechanism for coexistence in two sympatric mesopredator sharks

Global marine biodiversity declines require bold and ambitious plans to safeguard ecosystem services. Overfishing, habitat loss and projected climate impacts have yielded deleterious effects on marine predators, in particular, driving increasing threat of extinction for many shark species with implications for ecosystem health. Identifying and protecting critical habitat areas for sharks is fundamental to their protection, and may allow for species recovery. Here we use baited remote underwater video stations to investigate spatial and temporal patterns of habitat use by sharks in a Special Area of Conservation (SAC) that is centrally important to the regional blue economy in the UK, the Cardigan Bay SAC. Our results show heterogeneous spatial habitat use and temporal trends in habitat sharing between smallspotted catsharks Scyliorhinus canicula and nursehounds S. stellaris. Nearshore reef habitats are substantially more important than non-reef habitats for both species. The relative abundance of each species, however, is roughly inversely seasonally proportional, with S. canicula and S. stellaris relative abundance highest in March and September, respectively. Temporal niche partitioning may be an important mechanism in marine systems, but has not been widely investigated in sympatric shark communities. These findings are directly relevant for ongoing development of the Welsh Marine Evidence Strategy (2019-2025) and the Welsh National Marine Plan, particularly to inform spatial planning to strengthen the role of SAC management design in protecting important shark areas.

Lost in space and time: robust demography and enhanced resilience buffer adverse environmental effects in a highly isolated and sedentary pre-pleistocene landscape vertebrate

BackgroundFew animal populations have been studied under the framework of the OCBIL theory, which addresses the ecology and evolution of biodiversity on old climatically buffered infertile landscapes. Available genetic data challenge the low connectivity and high genetic differentiation predicted for isolated tepui-summit vertebrate communities, suggesting potential dispersal among summits. However, the OCBIL theory posits reduced dispersibility, enhanced resilience to habitat fragmentation and inbreeding due to small populations. We tested these hypotheses by conducting the first analytic evaluation of the spatial ecology and population biology of a tepui-summit vertebrate at multiple spatial scales.ResultsWe used harmonic radar tracking (100 individuals/448 points of contact) and capture-mark-recapture data (596 individuals captured/52 recaptured) to reveal the temporal niche, microhabitat use, population size, and dispersal abilities of the tepui-summit endemic toad Oreophrynella quelchii on Roraima-tepui. Abundance was determined using a closed population model incorporating sources of variation in capture probability. We tested the relative influence of biotic and abiotic variables on distances moved through model selection. Our data indicate that the population size of O. quelchii is remarkably large (ca. 12 million individuals), with strong seasonal demographic fluctuations. Ecology and observed limited spatial movements challenge the likelihood of active dispersal among tepui tops in this species. Our results are counter to those predicted by the available genetic data but support two hypotheses of the OCBIL theory: reduced dispersibility and enhanced resilience. However, they do not support the expectation of a small refugial population size.ConclusionWe postulate that the insular, hostile tepui-summit environment tends to produce robust demographic populations, likely to buffer stochastic adverse environmental effects, rather than diversity, as observed in much younger post-Pleistocene Neotropical landscapes. Our results draw attention to the value of faunal studies using an OCBIL framework to better understand the ecology and evolution of this unique biota worldwide.

Daily Activity Rhythms of Animals in the Southwest Mountains, China: Influences of Interspecific Relationships and Seasons

Temporal and spatial factors regulate the interactions between apex predators, mesocarnivores, and herbivores. Prey adjust their activity patterns and spatial utilization based on predator activities; in turn, predators also adapt to the activities of their prey. To elucidate the factors influencing the daily activity rhythms of animals, 115 camera traps were established from September 2019 to June 2023 to assess the influences of interspecific relationships and seasons on the daily activity rhythms of animals in the southwest mountains of China. The species captured by the cameras included six Carnivora (such as Panthera pardus and Lynx lynx), six Artiodactyla (such as Moschus spp. and Rusa unicolor), one Primate (Macaca mulatta), and two Galliformes (Crossoptilon crossoptilon, Ithaginis cruentus). The results demonstrated that the 15 species exhibited different activity rhythms and peak activities to reduce intense resource competition. There were differences in the species’ activity rhythms in different seasons, with competition among different species being more intense in the cold season than in the warm season. In predation relationships, the overlap coefficient in the cold season exceeded that of the warm season, possibly due to the abundant resources in summer and food scarcity in winter. In competitive relationships, 15 pairs of species exhibited significantly higher overlap coefficients in the cold season compared to the warm season, possibly due to increased demands for energy during the cold period or seasonal changes in predatory behavior. By analyzing the daily and seasonal activity patterns of dominant species in the study area, temporal niche overlaps were established to compare the competition levels between species. These findings indicate that the activity rhythms of the animals in this area not only result from evolutionary adaptation but are also influenced by season, food resources, and interspecific relationships (predation and competition). Thus, efforts should be made to reduce human interference, protect food resources in the winter, and monitor animals’ interspecific relationships to protect animal diversity and maintain the stability of the ecosystem in this biodiversity hotspot in China.

Elevated vitamin D levels in diurnally-active female fruit bats

Animal species have evolved to enhance their survival by focusing their temporal activity on specific parts of the diurnal-nocturnal cycle. Various factors, including inter-specific competition and anti-predator behavior, as well as anthropogenic effects like light pollution, have prompted some species to expand or shift their temporal niches. Our study focuses on the temporal niche shift of the Egyptian fruit bat (Rousettus aegyptiacus) to diurnal activity in Israel.Through an extensive citizen-science study, we assessed the distribution of these bats’ diurnal activity across Israel. We also documented the sex and age of bats from a colony known for its diurnal activity and collected blood samples from them for metabolic analysis.Our findings indicate that the shift toward daytime activity predominantly takes place in urban settings and is mostly exhibited by females. We found a significant physiological effect of this temporal shift, namely: diurnal bats’ vitamin D levels were significantly higher, and their parathyroid hormone (PTH) levels were significantly lower than those of nocturnal bats.We suggest that the reproductive metabolic demands of female bats might be a key factor driving this shift to diurnal activity. We hypothesize that the increase in vitamin D, derived from sunlight hours, might play a crucial role in regulating calcium homeostasis, thus contributing to the bats’ physiological needs during the reproduction season.

CSR strategies seasonal cycling: A new mechanism for coexistence among seaweeds

The stable maintenance of high biological diversity remains a major puzzle in biology. We propose a new mechanism involving the cyclical use of Competitive, Stress-tolerant, and Ruderal (CSR) strategies to explain high biodiversity maintenance. This study examines the interactions among three morphs of the cosmopolitan and commercially important seaweed Ulva Linnaeus. We measured biomass productivity, effective quantum yield, carbohydrate concentration, and nutrient competition across all seasons for one year and matched trait value combinations to CSR strategies. Our findings reveal that the Ulva morphs exhibited significant competitive interactions under eutrophic conditions, in a scramble competition dynamic. However, competition did not significantly affect their functional traits under naturally prevalent oligotrophic conditions. Season-by-season analysis revealed that each morph employed temporal niche partitioning by cyclically adopting different CSR strategies, thereby avoiding direct competition. This cyclical strategy, akin to a rock-paper-scissors game, prevents any single strategy from dominating year-round, maintaining the three-morph polymorphism. Our study further highlights the importance of year-long functional trait measurements to encompass seasonal changes in functional responses. Our CSR cycling conceptual model offers new insights useful for monitoring and conservation efforts.

Temporal and trophic niche partitioning among arboreal ants in a Neotropical woodland savanna

Abstract Niche partitioning is a key mechanism for explaining species coexistence, including the coexistence of ants in trees of the Brazilian savanna (cerrado). However, we have limited information on the extent to which arboreal ant species exploit different food resources and/or have different daily foraging schedules. We tested these ideas through a baiting experiment, and by measuring the isotopic signature (δ15N) and the critical thermal maximum (CTmax) of the 14 most common species found in a typical cerrado tree species. Although most species foraged on all bait types offered, species‐specific preferences were noted for about one‐third of the species. We also found a wide variation in mean δ15N between species, reflecting interspecific differences in trophic position. Most (71.4%) species foraged predominantly on a given period of the day, ranging from strictly nocturnal species to those that foraged mainly in the afternoon. Species with a higher heat tolerance (higher CTmax) often foraged at warmer periods of the day than those with a lower tolerance. Despite the evidence of trophic and temporal niche partitioning, other mechanisms, such as nesting site specialization and behavioural trade‐offs, are required to explain species coexistence in this arboreal ant assemblage, as several species pairs largely overlapped both in their diet and time of foraging. Importantly, our results provide additional support for the idea that physiological restriction to high temperatures is important for understanding interspecific differences in foraging activity schedules.

Incorporating seasonality, predictability, and modularity into the optimization of biodiversity conservation for ecological networks

Improving the connectivity of ecological networks (ENs) is a proven strategy for biological conservation. However, without a clear understanding of animal movement, research on ENs may not provide a sufficient reference for maintaining biodiversity. To address this gap, we embraced central concepts of movement ecology and conducted a study in the Qilian Mountains. The predictability and seasonality of environmental conditions were combined to identify ecological sources with rich temporal niches and improve the informed preference character of resistance surface. Then, we constructed ENs with six dispersal thresholds. Further, integrating modularity and circuit theory, we pinpointed priority areas for restoration within the ENs. Our findings indicated that the eastern part of the Qilian Mountains showed higher biodiversity suitability, with terrain being the primary factor limiting dispersal. Additionally, comparative analyses demonstrate that the new method for measuring biodiversity from the perspective of temporal niche is reliable and better aligns with the needs of biodiversity conservation. In light of emerging challenges within the study area, where apex predators seriously suppress the populations of some smaller predators, we propose a novel conservation idea that emphasizes the strategic retention and removal of barriers to maintain biological balance. This study enriches methodologies for biodiversity measurement, provides forward-looking conservation strategies, and offers practical contributions toward mitigating biodiversity loss.

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

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.

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

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

Seasonal Variation in Mammalian Mesopredator Spatiotemporal Overlap on a Barrier Island Complex.

Due to lack of apex predators in human-dominated landscapes, mesopredator relationships are complex and spatiotemporal niche partitioning strategies can vary, especially when seasonal shifts in resource availability occur. Our objective was to understand spatiotemporal niche overlap across seasons among mesopredators inhabiting a barrier island complex. We placed 19 unbaited cameras throughout Fort De Soto County Park, Florida, USA between February 2021 and July 2023. Of six mesopredator species detected, three species had >75 detections during both the wet and dry seasons (coyote, Canis latrans; Virginia opossum, Didelphis virginiana; and raccoon, Procyon lotor). Using general linear mixed models, we determined that during the wet season coyote-raccoon and raccoon-opossum detections were positively associated with each other (p < 0.05). During the dry season, raccoon-opossum detections were positively associated, and opossums were more likely to be detected around mangroves. After calculating coefficients of overlap, we found all three species varied their temporal activity between seasons. During the dry season exclusively, all three mesopredators occupied different temporal niches. The park's isolated but developed nature has potentially led to a destabilized mesopredator community. Understanding seasonal mesopredator dynamics of Fort De Soto is particularly important because this park supports a high number of nesting shorebirds and sea turtles, which are known food sources for mesopredators.

Phylogenetic proximity drives temporal succession of marine giant viruses in a five-year metagenomic time-series.

Nucleocytoplasmic Large DNA Viruses (NCLDVs, also called giant viruses) are widespread in marine systems and infect a broad range of microbial eukaryotes (protists). Recent biogeographic work has provided global snapshots of NCLDV diversity and community composition across the world's oceans, yet little information exists about the guiding 'rules' underpinning their community dynamics over time. We leveraged a five-year monthly metagenomic time-series to quantify the community composition of NCLDVs off the coast of Southern California and characterize these populations' temporal dynamics. NCLDVs were dominated by Algavirales (Phycodnaviruses, 59%) and Imitervirales (Mimiviruses, 36%). We identified clusters of NCLDVs with distinct classes of seasonal and non-seasonal temporal dynamics. Overall, NCLDV population abundances were often highly dynamic with a strong seasonal signal. The Imitervirales group had highest relative abundance in the more oligotrophic late summer and fall, while Algavirales did so in winter. Generally, closely related strains had similar temporal dynamics, suggesting that evolutionary history is a key driver of the temporal niche of marine NCLDVs. However, a few closely-related strains had drastically different seasonal dynamics, suggesting that while phylogenetic proximity often indicates ecological similarity, occasionally phenology can shift rapidly, possibly due to host-switching. Finally, we identified distinct functional content and possible host interactions of two major NCLDV orders-including connections of Imitervirales with primary producers like the diatom Chaetoceros and widespread marine grazers like Paraphysomonas and Spirotrichea ciliates. Together, our results reveal key insights on season-specific effect of phylogenetically distinct giant virus communities on marine protist metabolism, biogeochemical fluxes and carbon cycling.

Day-night gene expression reveals circadian gene disco as a candidate for diel-niche evolution in moths.

Temporal ecological niche partitioning is an underappreciated driver of speciation. While insects have long been models for circadian biology, the genes and circuits that allow adaptive changes in diel-niches remain poorly understood. We compared gene expression in closely related day- and night-active non-model wild silk moths, with otherwise similar ecologies. Using an ortholog-based pipeline to compare RNA-Seq patterns across two moth species, we find over 25 pairs of gene orthologs showing differential expression. Notably, the gene disco, involved in circadian control, optic lobe and clock neuron development in Drosophila, shows robust adult circadian mRNA cycling in moth heads. Disco is highly conserved in moths and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We propose disco as a candidate gene for the diversification of temporal diel-niche in moths.

Mapping terrestrial mammals in China based on species richness of functional groups

Biodiversity loss is one of the most critical environmental issues globally. Functional diversity and functional groups, extending and expanding the concept of species richness, provide a more comprehensive understanding of biodiversity. By integrating mathematical indices calculation with classical geospatial statistical analysis and mapping techniques, we explored and visually illustrated the spatial patterns and regularities of functional diversity. This approach shed light on the functional diversity of China’s terrestrial mammals from a macroecological perspective. We found that in terms of overall quantity composition, underground-living mammals (UG groups) had the highest proportion (55.1%) in the vertical niche dimension, while nocturnal mammals (NO groups) dominated (58.6%) the in temporal niche dimension. Employing grid cells as fundamental units, in most grid cells, the proportion of UG and NO groups exceeded 50%, consistent with the overall quantity results. Examining the spatial distribution of functional group species richness from different perspectives reveals varying patterns. For instance, standard deviations of vertical and temporal niches showed different spatial clustering traits on either side of the Hu Huanyong Line. In a specific dimension of functional diversity, the numerical differences among functional groups are larger in grasslands with homogenous vegetation, while in forests with diverse vegetation types, these differences are minimized. Additionally, if there is a large disparity in species richness among functional groups in one dimension, there may be a smaller disparity in another. These findings offer a macroecological perspective for biodiversity research, providing insights for interdisciplinary studies in basic ecology, conservation biology, and geography, and offering scientific guidance for mammal conservation.

Temporal temperature shifts govern the population succession of picoeukaryotes and picocyanobacteria in a coastal ecosystem

Picophytoplankton are vital components of the marine microbial food web. Being the smallest in the phytoplankton group, their short life cycles make them excellent bioindicators of environmental conditions. Given this, an investigation was conducted at the Kandla Port ecosystem (Latitude 23º 01' N; Longitude 70º 13' E) in the state of Gujarat, India to assess the response of picophytoplankton community structure to temporal and spatial environmental conditions. The sampling was conducted in July 2015, October-November 2015, and February 2016 at twenty-six stations. The results revealed a wide annual temperature range due to the study site's proximity to the Tropic of Cancer. The salinity ranged up to 40 while the turbulence caused by the macrotides resulted in highly turbid waters, especially during July due to precipitation. The picophytoplankton community was represented by picocyanobacteria (three sub-groups of Synechococcus) and picoeukaryotes (three sub-groups including Cryptophytes). The picocyanobacteria were abundant during the less turbid, warmer October-November period and lower during the cooler February period. The dominant Synechoccocus groups are associated positively with NH4+ and negatively with PO43-. The Cryptophytes were present during the warm and cool periods indicating tolerance to a wide range of temperature, salinity, and light. Their positive correlation with PO43- and NH4+ concentrations during February and October-November, respectively suggests a causal relationship. The picoeukaryotic group dominated the picophytoplankton community during the cooler period (February). The relative importance of the two picophytoplankton groups changed throughout the year exhibiting temporal niche segregation and hence establishing their role as bioindicators of temperature.

Involvement of the gut microbiota in the metabolic phenotypes of two sympatric gerbils

Temporal niche partitioning is a crucial strategy for sympatric species to avoid predation and competition for habitat space and food resources. This study investigated the effect of the gut microbiota on the metabolic rhythms of two sympatric gerbil species (Meriones unguiculatus and Meriones meridianus) to test the hypothesis that the oscillatory patterns of microbiota may not fully mirror those of the host's metabolism. Experiment 1 compared the circadian metabolic and gut microbiota rhythms of M. unguiculatus (n = 12) and M. meridianus (n = 12) and measured the subjects' body temperatures and environmental temperature preferences. In Experiment 2.1, six M. meridianus gerbils were treated with antibiotics, and in Experiment 2.2, 21 M. unguiculatus gerbils (seven per treatment) were randomly gavaged with saline or a gut microbiota suspension from either M. unguiculatus or M. meridianus; their metabolic rhythms were subsequently measured. The results showed that the two gerbils had different metabolic phenotypes that determined activity heterogeneity and contributed to their coexistence. The relative abundances of Bacteroidetes, Actinobacteria, and Cyanobacteria in M. meridianus varied rhythmically in parallel with the daily metabolic rate, which was significantly higher at night than during the day. The rhythm of the metabolic rate was not noticeable in M. unguiculatus. However, in M.unguiculatus, the relative abundances of Firmicutes, Bacteroidetes, Proteobacteria, and Verrucomicrobia were significantly higher during the day than at night, while Cyanobacteria exhibited the opposite pattern. Antibiotic treatment significantly weakened the metabolic rhythms of M. meridianus, and the circadian rhythms slowly recovered after stopping antibiotic gavage. However, after transplanting M. meridianus' gut microbiota into M. unguiculatus, the metabolic rate of M. unguiculatus was not significantly different from that of the control groups. Our hypothesis was partly supported: the microbiota was only partially involved in regulating the metabolic rhythms of gerbils, and other factors could compensate for the effect of the gut microbiota on host metabolic rhythms. This finding underscores the complexity of host–microbiota interactions and highlights the need for further exploration into the multifaceted mechanisms governing host metabolic regulation.

Autumn Leucojum autumnale and spring L. trichophyllum: the same flower type for different seasons with a different pollination scenario

Plant reproduction may experience distinct evolutionary and ecological dynamics depending on their flowering phenology. Consequently, floral traits might undergo divergence selection to adapt to the difference in the abiotic and the biotic environment, especially if these traits affect intensity of competition plants experience due to pollinators. The present study analyzed the plant floral display, floral rewards, and the pollination and breeding systems of two related species of Leucojum, the autumn-blooming L. autumnale and the spring-blooming L. trichophyllum. The aim of the current study is to compare reproductive aspects of L. autumnale and L. trichophyllum due to differing environmental conditions. Both species needed pollinators to reproduce sexually, with zero (L. trichophyllum) or low values (c. 7.7%; L. autumnale) for fructification after self-pollination vs. over 90% after natural pollination (both species). Their flowers opened in the morning and closed at night, and neither produced nectar, only pollen as reward to pollinators. Plants of the L. autumnale studied population produced 1–4 inflorescences per plant vs. only 1 in L. trichophyllum, and the former presented a greater density of flowers per surface unit. Leucojum autumnale flowers were visited by Hymenoptera and those of L. trichophyllum only by two Coleoptera, which were most abundant at sunrise and sunset, whereas in the middle of the day, they visited Cistaceae flowers. This latter occurrence may represent a temporal niche partitioning rather than competition in relation to visiting hours, as the L. trichophyllum flowers offer a place for insects to spend the night, a period in which the flowers of the Cistaceae species have lost their petals.