摘要: The role of miRNAs in the regulation of seasonal reproduction in rodents, particularly in relation to photoperiod changes, is still poorly understood. Previous studies on miRNA transcriptomes of striped hamster (Cricetulus barabensis) testes have indicated that the photoperiodism of testes, especially apoptosis, may be influenced by miRNAs. As a functional miRNA, cba-miR-222-3p in striped hamster testes exhibits suppression under a short photoperiod. To elucidate the potential role of testicular cba-miR-222-3p in the seasonal reproduction of striped hamsters, we exposed male striped hamsters to different photoperiods or injected miRNA agomir into the testes and observed the effects of these treatments, particularly some indicators related to apoptosis. The results showed that the levels of apoptosis in the testes increased in short daylength, accompanied by a significant decrease in cba-miR-222-3p expression and an increase in TRAF7 expression. Dual luciferase reporter assays verified the targeting relationship between cba-miR-222-3p and TRAF7 predicted by bioinformatics. In addition, the expression of TRAF7 decreased in the testes, which injected miRNA agomir, leading to inhibition of apoptosis, and the expression of key genes (MEKK3, p38, p53) in the downstream MAPK signaling pathway of TRAF7 was suppressed. These results suggest that short daylength induces testicular apoptosis in striped hamsters, and one possible mechanism is that the decreased expression of miR-222-3p in testes reduces the repression of TRAF7 translation, thereby activating the MAPK pathway and affecting the level of testicular apoptosis. These findings reveal the potential role of miR-222-3p in animal reproduction and provide new insights into the regulation of rodent populations.

摘要: Urbanization is a global phenomenon that involves the transformation of natural areas into urban spaces, thereby subjecting organisms to new selective pressures including a wide variety of pollutants and changes in intra- and interspecific interactions. Considering that projections indicate that by the year 2050, 65% of the human population will live in urban areas and that urbanization is a phenomenon with an upward pattern, identifying these phenotypic traits is vital to implementing conservation and management plans for urban fauna. The urban environment may exert different selective pressures on sexually selected traits than more pristine environments, a phenomenon which has been well studied in birds but is less understood in other vertebrates such as lizards, although they are common inhabitants of urban environments. Here, we compare sexual coloration, parasite load, and immune response in Sceloporus torquatus lizards in urban and non-urban environments of Central Mexico. Our study shows that sexual coloration is more saturated (bluer) in male lizards from urban environments, while UV chroma was higher in non-urban lizards. The average parasite load is lower in urban lizards than in non-urban lizards, and we found a negative relationship between hemoparasite count and sexual coloration in male lizards from non-urban environments but not in male lizards from urban environments. Additionally, non-urban lizards exhibited a higher immune response. In female lizards, sexual coloration differed significantly between urban and non-urban environments, but parasite load and immune response did not differ. These results may be useful to improve herpetofauna conservation plans in urbanized environments.

摘要: Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38-h period, community structure became similar to pre-shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology.

摘要: Animals may experience early negative (mechanical pain: being retrieved using an incisor by parents or attacked) or positive stimulation (being licked and groomed) that may affect emotional and social behaviors in adulthood. Whether positive tactile stimulation can reverse adverse consequences on emotional and social behaviors in adulthood resulting from chronic mechanical pain and underlying mechanisms remain unclear. This study used a tail-pinching model during development to simulate mechanical pain experienced by pups in high-social mandarin voles (Microtus mandarinus). Subsequently, brush-like positive tactile stimuli were applied to the backs of the mandarin voles. Various behavioral tests were used to measure levels of anxiety, depression, and sociability. The results showed that early tail-pinching delayed the eye opening of pups, increased levels of anxiety, reduced levels of sociality in male mandarin voles, and impaired social cognition in females during adulthood. Brushing on the back reversed some of these effects. While mandarin voles that were exposed to tail-pinching during development were exposed to sub-threshold variable stress as adults, they were more likely to show a stress-induced increase of anxiety-like behavior, reduction of sociability, and impairment of social cognition, displaying heightened susceptibility to stress, particularly in males. However, back-brushing reversed some of these effects, implying that these adults display enhanced stress resilience. In addition, tail-pinching reduced levels of serum oxytocin and increased corticosterone levels in serum, but back-brushing reversed these effects. Overall, it was found that positive tactile stimulation reversed increases in anxiety and impairments of social behavior induced by negative stimulation in male mandarin voles via alteration of oxytocin and corticosterone levels. This study used a tail-pinching model during development to simulate mechanical pain experienced by pups in high-social mandarin voles (Microtus mandarinus). Subsequently, brush-like positive tactile stimuli were applied to the backs of the mandarin voles. It was found that positive tactile stimulation could reverse the increases in anxiety and impairments of social behavior induced by negative stimulation in male mandarin voles via alterations of oxytocin and corticosterone levels. image

摘要: The acoustic ecology of a previously unexamined dolphin population in the Mediterranean was assessed by investigating how sound emissions and acoustic features are influenced by concurrent conditions. Whistles and click-trains emission rates were compared among different environmental, social and behavioural conditions. Structural variability of 3928 good/high-quality vocalizations was analysed in relation to contexts through a two-stage approach. First, two multivariate MANOVA-models were fitted considering the entire set of acoustic parameters extracted from whistles and click trains, to investigate the effect of concomitant factors on the overall acoustic structure of each vocalization. Subsequently, GLMM models were applied to each acoustic feature individually to explore its response to different contextual factors. Emission rates increased significantly with calves and in larger groups, with also a positive effect of socialization on whistles and of muddy/sandy seabed and depth on impulsive sounds. The multivariate approach showed that all contextual factors influenced sounds' structure, with whistles being strongly affected by behaviour and calves' presence. The GLMM models highlighted that each acoustic parameter varied differently in response to specific factors, with (1) increasing trends in whistles' duration and inflection points during interaction with fishery and decreasing ones during socializing, and (2) decreasing inter-click-intervals and increasing click-repetition-rates in larger groups and during interactions with fishery. These results provide new findings on the acoustic plasticity of bottlenose dolphins and a more comprehensive view of the magnitude of the social, environmental and behavioural influence, highlighting how the complexity of the species' acoustic repertoire has yet to be unravelled at the local level.

摘要: Many plants exhibit a canopy seed bank, where seeds persist within the canopy for prolonged periods, gradually descending over time and potentially influencing seed predation and animal-mediated dispersal. However, the impact of delayed seed drop on animal predation and seed dispersal remains unclear. We used Chinese Armand pine seeds to simulate delayed seed drop of the canopy seed bank by releasing 7800 pine seeds in both winter and the following summer over 2 years, tracking their fates to investigate its effect on seed predation and dispersal by rodents in a pine plantation in southwest China. Results showed significant seasonal differences in seed fate. In summer, seeds experienced higher predation rates (62.08% vs 3.80% in winter) and lower scatter-hoarding rates (4.18% vs 15.40% in winter). Additionally, seeds in summer were dispersed farther (4.20 m vs. 3.56 m in winter) and primarily formed single-seed caches, as opposed to multi-seed caches in winter. Although delayed seed drop increased immediate predation risks, favorable summer conditions allowed for rapid germination, reducing long-term exposure to predation. In conclusion, while delayed seed drop increases immediate predation risks and reduces caching, it concurrently enhances dispersal distances and reduces cache size. While delayed seed drop increases immediate predation risks and reduces caching, it concurrently enhances dispersal distances and reduces cache size. image

摘要: Intertidal organisms usually live near their upper thermal limits, and are vulnerable to future global warming. As a vital response to thermal stress, thermoregulatory strategy in physiological and behavioral performance is essential for organisms coping with thermal stress and surviving the changing world. To investigate the relationship between the thermoregulatory strategy and habitat temperature, in the present study, we comparatively investigated the thermal responsive strategy among different geographic populations of the supralittoral snail Littoraria sinensis by determining snails' cardiac function and behavioral performance. Our results indicated that populations inhabiting high ambient temperatures had higher sublethal temperatures (i.e. Arrhenius breakpoint temperatures, ABTs, the temperature at which the heart rate shapely decreases with further heating) and lethal temperatures (i.e. Flatline temperatures, FLTs, the temperature at which heart rate ceases), and behaved less actively (e.g. shorter moving distances and shorter moving time) in the face of high and rising temperatures-a physiological fight strategy. On the other hand, populations at relatively low ambient temperatures had relatively lower physiological upper thermal limits with lower ABTs and FLTs and moved more actively in the face of high and rising temperatures-a behavioral flight strategy. These results demonstrate that the thermoregulatory strategies of the snails are closely related to their habitat temperatures and are different among populations surviving divergent thermal environments.

摘要: How organisms respond to complex environments is one of the unsolved problems in ecology. Life history patterns of a species provide essential information on how different populations may respond and adapt to environmental changes. Compared to typical seasonal breeders, which have limited distributions, the worldwide distribution of brown rats (Rattus norvegicus) across highly complex and divergent habitats suggests they exhibit exceptional adaptiveness. However, the difference in physiological mechanisms by which brown rats respond and adapt to markedly different environments is seldom investigated. Here, we reveal a significant divergence in reproductive seasonality and environmental responses between two brown rat subspecies: one subspecies, R. n. caraco, lives in the temperate zone, and another subspecies, R. n. norvegicus, lives in the subtropical region. Although R. n. caraco displayed a significantly higher reproductive seasonality than R. n. norvegicus, both subspecies adapted to sub-optimal breeding conditions mainly by regulating the seminal vesicle rather than testis development. Especially in responding to severe winter conditions in high-latitude regions, bodyweight-dependent recovery of testicular development in adults enables R. n. caraco to initiate reproduction more rapidly when conditions are suited. These findings elucidate a regulatory process of how brown rats live as opportunistic breeders by benefiting from enhanced semen production.

摘要: Sexual size dimorphism theory predicts biased operational sex ratios (OSRs) and an uneven distribution of males among certain females. We studied this phenomenon through a field census of the giant wood spider Nephila pilipes (family Nephilidae) in Singapore, a species where females are, on average, 6.9 times larger than males. Specifically, we tested two hypotheses concerning male distribution, given their tendency to aggregate in certain female webs. The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females. The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart. Our snapshot census revealed a female-biased OSR (females: males = 1.85) with an uneven distribution of males in female webs. Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis. Proximity among female webs was indicative of male presence, lending support to the web clustering hypothesis. While our study's limited sample size warrants caution, we conclude that in N. pilipes, male occupation of female webs is facilitated by the clustering of webs, and males prefer to cohabit with optimally sized, receptive females.

摘要: Rodents are important seed dispersers of plants because they move seeds far away from the parent trees and hoard seeds in the soil, benefiting seed dispersal and regeneration. Traits of plant seeds and animals are associated with rodent-mediated seed dispersal, but animal personality, the consistent individual behavioral differences in time and environments, has not been fully considered. Here, we first measured the personality of 26 Niviventer confucianus in the laboratory, and 10 individuals in the field of one population, and then tested their behavior of seed consumption and hoarding both in semi-natural enclosures and the field. We tested the hypothesis that individuals with different personalities have different preferences for seed consumption and hoarding, which has different implications for seed dispersal and regeneration. Under the enclosure conditions, all parameters of personality are repeatable; bold individuals harvested fewer seeds but scatter-hoarded more seeds and dispersed farther than timid ones, whereas active individuals consumed more seeds, but left fewer seeds on the ground surface than inactive ones. In the field, boldness, activity, and exploration of the animals are repeatable; bold individuals scatter-hoarded more seeds to farther distances than timid ones, whereas active individuals harvested and consumed more seeds than inactive ones. These results suggest that bold rats tended to scatter hoard seeds and disperse them to a longer distance, implying they are more effective in seed dispersal. In the future, animal personality (e.g. boldness and activity) should be considered in seed dispersal studies and ecological-based manipulation in seed dispersal and regeneration of forests.