Search Results (88)

Understanding the mechanisms underlying seasonal community dynamics is important for predicting biodiversity responses to environmental fluctuations, enhancing ecological forecasting, and informing conservation strategies. In this study, we use standard transect and mist netting methods investigated seasonal altitudinal migration patterns of montane bird species in the Gyirong Valley, Central Himalayas. Our results showed four distinct altitudinal migration patterns among montane bird species: no shift, downslope shift, upslope shift, and contraction to mid-elevation zones. Species with smaller body weight and higher ratios of wing length, tail length, and tarsus length to body weight tended to migrate to lower elevations. Insectivorous birds exhibited a collective downslope shift, while omnivorous birds showed a wider range of migratory responses to seasonal variation. Migratory behavior was found to dynamically modulate the association between phenotypic traits and habitat preferences. During the breeding season, species (70.44%) and functional turnover (80.02%) dominated, while in the non-breeding season, nestedness significantly contributed to species (49.37%) and functional diversity (38.09%). In addition, migration can disrupt the direct influence of environmental variables on biodiversity patterns, providing important insights for montane biodiversity conservation under climate change. Our results highlight the critical need to safeguard low-elevation winter habitats and create dynamic protected areas to aid bird conservation amidst climate change. Full article

The Military Macaw is a Neotropical psittacid that is endangered in Mexico. It faces significant threats due to habitat loss and the illegal pet trade. However, little is known about the nutritional characteristics of the plant resources available to this species throughout its annual cycle. This study aimed to characterize the nutritional profile of the fruits consumed by macaws in the Alto Balsas Basin, Mexico, and to infer potential seasonal patterns in the availability of the fruits they feed on in relation to the Macaws’ reproductive phenology. We identified 13 plant species that have been consistently reported as components of the diet of the macaws within the Alto Balsas Basin using a literature review, field observations, and local interviews. We conducted bromatological analyses to assess the content of moisture, protein, lipids, carbohydrates, and fiber for the pulp and seeds of all 13 identified plant species. Although we did not measure quantitative food intake, we integrated these data with reproductive phenology and resource availability to infer potential patterns of nutritional use. The results revealed significant differences in nutritional content among the different species, as well as seasonal variation in the nutritional profiles of available resources that coincide with the physiological demands of the macaw life cycle. During the non-breeding season, the availability of species whose fruits have high lipid and carbohydrate contents, such as Bursera spp., hackberry and madras thorn, may provide essential energy. Conversely, during the breeding season, resources with higher lipid and protein content (such as Mexican kapok tree and red mombin) could support the increased energetic investment associated with courtship, egg production, and chick provisioning. Although our study did not directly quantify the amount of each food item consumed, the integration of nutritional and ecological data provides a preliminary view of how resource quality may influence seasonal foraging patterns, offering valuable insights for the conservation and management of this species. Full article

The activation mechanism of the reproductive axis in Kazakh ewes during the non-breeding season was explored by supplementation with glycerol complex (7% glycerol + tyrosine + vitamin B9). The experiment divided 50 ewes into five groups (n = 10). After 90 days of intervention, it was found that significant changes in serum DL-carnitine, N-methyl-lysine and other differential metabolites were observed in the GLY-Tyr-B9 group (p < 0.05, “p < 0.05” means significant difference, “p < 0.01” means “highly significant difference”). The bile acid metabolic pathway was specifically activated (p < 0.01). The group had a 50% estrus rate, ovaries contained 3–5 immature follicles, and HE staining showed intact granulosa cell structure. Serum E2/P4 fluctuated cyclically (p < 0.01), FSH/LH pulse frequency increased (p < 0.01), peak Glu/INS appeared on day 60 (p < 0.05), and LEP was negatively correlated with body fat percentage (p < 0.01). Molecular mechanisms revealed: upregulation of hypothalamic kiss-1/GPR54 expression (p < 0.01) drove GnRH pulses; ovarian CYP11A1/LHR/VEGF synergistically promoted follicular development (p < 0.05); the HSL of subcutaneous fat was significantly increased (p < 0.05), suggesting involvement of lipolytic supply. Glycerol activates the reproductive axis through a dual pathway—L-carnitine-mediated elevation of mitochondrial β-oxidation efficacy synergizes with kisspeptin/GPR54 signalling enhancement to re-establish HPO axis rhythms. This study reveals the central role of metabolic reprogramming in regulating seasonal reproduction in ruminants. Full article

The poll gland, a specialized tissue of male Bactrian camels, undergoes seasonal enlargement and marked metabolic activation during the rutting season. However, the metabolic mechanisms of the poll gland and its role in rutting activities and inducing estrus are still not fully understood. This study aimed to investigate the contribution of fatty acid metabolic pathways, specifically those mediated by carnitine palmitoyltransferase 1A (CPT1A), in poll gland activity during the breeding season; poll gland tissue, neck mane, and urine samples were systematically collected from healthy male Bactrian camels stratified into breeding and non-breeding season groups for integrated proteomic, metabolomic, and biochemical assays. Histological and immunohistochemical analyses revealed reduced adipocytes but elevated ATP production in rutting camels, suggesting increased mitochondrial activity and enhanced oxidative phosphorylation. Proteomic analyses identified 119 differentially expressed proteins (DEPs) linked to fatty acid metabolism, with CPT1A, a key regulator of mitochondrial fatty acid oxidation, emerging as a central hub. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis further confirmed enrichment in fatty acid biosynthesis, degradation, and PPAR/AMPK signaling. The metabolomic analysis identified 14 metabolites, including acetylcarnitine and glycine, that were closely correlated with CPT1A expression, suggesting their potential involvement in regulating fatty acid metabolism during the breeding season. Quantitative expression analyses revealed that CPT1A in glandular acini was significantly upregulated in the breeding group compared to the non-breeding group across all assays: qPCR (2.53-fold, p < 0.05), Western blot (3.5-fold, p < 0.05), and immunohistochemistry (1.5-fold, p < 0.05). This demonstrated that CPT1A-mediated fatty acid metabolism plays a pivotal role in energy provision for reproductive activities. The results suggested that CPT1A-mediated fatty acid oxidation sustains poll gland function and reproductive behaviors in male Bactrian camels. This study provided a theoretical basis for understanding the role of CPT1A-mediated fatty acid oxidation in maintaining poll gland function and supporting reproductive activities in male Bactrian camels. Full article

In this study, we identified two β-hexosaminidase A isoforms (Mn-HexA1 and Mn-HexA2) in Macrobrachium nipponense through bioinformatics analysis and characterized their phylogenetic relationships. The open reading frames of Mn-HexA1 and Mn-HexA2 were 1641 bp (encoding 546 amino acids) and 1473 bp (encoding 490 amino acids), respectively. Both isoforms exhibited high conservation, sharing five identical functional domains, with 58.43% amino acid sequence similarity. Quantitative PCR analysis revealed that Mn-HexA1 expression was significantly higher than Mn-HexA2 across all developmental stages and tissues. During embryonic development, Mn-HexA1 showed elevated expression at the ZS, L15, and PL10, while Mn-HexA2 was upregulated only at L15 and PL10. In the breeding season and non-breeding season, Mn-HexA1 and Mn-HexA2 were predominantly expressed in the hepatopancreas at levels significantly higher than in other tissues. Moreover, their expression in most tissues was higher during the breeding season than in the non-breeding season. RNA interference experiments revealed that knockdown of both Mn-HexA isoforms significantly accelerated ovarian development in M. nipponense, with the Mn-HexA1-silenced group exhibiting faster progression than the Mn-HexA2-silenced group. These results demonstrate that Mn-HexA genes function as negative regulators of ovarian maturation, with Mn-HexA1 exerting a stronger inhibitory effect than Mn-HexA2. Full article

The concurrent occurrence of summer heat stress and the non-breeding season has significantly impaired the semen quality of rams. Currently, there exists no straightforward and efficient method to address this issue. In this study, we demonstrate that two consecutive administrations of melatonin implants significantly mitigate the adverse effects of summer heat stress and the non-reproductive season on rams. Our findings indicate that implantation of exogenous melatonin enhances semen quality by improving sperm DNA integrity, mitochondrial integrity, and decreasing the proportion of abnormal sperm, as compared to control rams. This improvement is ascribed to the alleviation of oxidative stress and the optimized regulation of endocrine hormone levels in both serum and seminal plasma. Further exploration of the regulatory mechanism reveals that melatonin can also influence the tryptophan metabolism pathway. Additionally, our study revealed that certain indices and metabolites are strongly correlated with semen quality and can potentially serve as indicators for research aimed at improving semen quality. Notably, this is the first time that differences in tryptophan metabolites between serum and seminal plasma have been elucidated. All the above information suggests that melatonin implantation can protect sperm from heat stress by optimizing the blood and semen microenvironment. Full article

Exploratory behavior involves gathering information and reflects how individuals interact with their environments. In seasonal environments, individuals undergo environmental cycles that might lead to differences in this behavior between locations and seasons. Here, we compare the exploratory behavior measured during an open-field test in 102 adult individuals of rufous-collared sparrow (Zonotrichia capensis) from three locations in central and southern Chile. A generalized mixed-effect model (GMM) was utilized to compare the exploratory behavior between locations and seasons. The two-way interaction between both variates was also included. Body mass and sex were included as covariates and elevation of the study sites as a random effect. The result indicates that exploratory behavior significantly varied between populations and seasons. Specifically, birds tested in the Chilean central zone (33° S) and breeding birds showed higher exploration scores during the open-field test than birds tested in the southern zone (38° S) and non-breeding birds. These findings suggest that exploratory behavior may be driven by local environmental pressures, underscoring the role of weather and seasonality in shaping this behavior. Full article

Lake Żarnowieckie, one of the largest lakes in northern Poland, hosts a high number of waterfowl during the non-breeding season. This study presents data on bird abundance from two periods. From 1986 to 1990, coinciding with the early colonization of the lake by zebra mussels Dreissena polymorpha, counts were conducted monthly between October and April. From 2011 to 2025, only one count was performed in January. Between 1986 and 1990, the highest numbers of waterfowl were observed in November and December, with maximum counts exceeding 20,000 birds. Three most abundant species—Eurasian coot Fulica atra, tufted duck Aythya fuligula, and mallard Anas platyrhynchos—accounted for 95–98% of all waterfowl. In January, their numbers significantly decreased, remaining low in the following months. This sharp decline mainly affected diving benthivores (tufted duck and Eurasian coot), which exerted strong pressure on prey populations, leading to a rapid decrease in their numbers and forcing a shift in foraging sites. The greatest decrease occurred in seasons with the highest number of waterfowl in December, when diving benthivores were most abundant and applied the greatest pressure on benthic organisms. These seasonal changes suggest that a single January count may not fully represent the significance of the lake for waterfowl. Over the study period, both ichthyophages, the great cormorant Phalacrocorax carbo and great crested grebe Podiceps cristatus, showed substantial increases in number. For cormorants, this growth coincided with the increase in the European population, while the rise in great crested grebes likely exemplifies the establishment of a new wintering site for this species in a location rich in food and free from intense human disturbance. Full article

The Shiquan River National Wetland Park in Tibet is an integrated high-elevation wetland ecosystem. This wetland park also serves as a demonstration site for international river conservation and the ‘conservation–utilization–sustainable enhancement’ of wetland resources in alpine desert zones. This study supplements the research on bird community structure and ecological function to fill the gap in basic data on birds in the Shiquan River National Wetland Park. From May 2023 to October 2024, a sampling point method was used to conduct four systematic surveys during the breeding and non-breeding periods of birds in four habitats—grass land, marsh land, bare land, and water bodies—in the Shiquan River National Wetland Park to explore the effects of different habitat types on bird communities from the perspective of species and functional diversity. A total of 56 bird species, representing 23 families and 11 orders, were documented in this survey. Species diversity was highest in the marsh habitat during the breeding season, followed sequentially by grassland, bare land, and water bodies, with consistent results in the non-breeding period. The functional richness (FRic) results revealed a pattern of marsh land > grass land > bare land > water bodies, indicating that birds utilized the ecological space within the marsh habitat to the greatest extent. The functional differentiation (FDiv) results followed a pattern of bare land > water bodies > grass land > marsh land, suggesting stronger niche complementarity and weaker competition in bare ground habitats. Finally, the functional dispersion (FDis) results demonstrated a pattern of grass land > marsh land > bare land > water bodies, indicating a greater number of species with similar functional traits in grass habitats. This study addresses the research gap concerning bird communities in the Shiquan River National Wetland Park through the lens of both species and functional diversity, thereby providing a scientific foundation and critical support for the conservation of avian biodiversity in the Shiquan River Basin and high-elevation regions. Full article

The aim of this study was to investigate the effect of season (breeding vs. non-breeding) on the characteristics of warmblood stallion spermatozoa during liquid storage. Ejaculates were collected from eight stallions during the breeding and non-breeding seasons (March–July and September–December, respectively) and were diluted in an EquiPro extender. Semen was stored for up to 96 h at 5 °C. Analysis of stored sperm included the assessment of motility (CASA system), acrosomes with normal apical ridges (NAR), plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP) content. In sperm stored for up to 24 h, the values of the following parameters were higher (p ≤ 0.05) in March-July than in September–December: progressive motility (PMOT), PMI, MMP, beat cross frequency (BCF), and linearity (LIN). The values of the studied parameters decreased during storage, and the observed changes were affected by season. The values of NAR, PMI and MMP, average path velocity (VAP), straight line velocity (VSL), and curvilinear velocity (VCL) decreased (p ≤ 0.05) after 24 h of storage during the breeding season, whereas a significant decrease in these parameters was observed after prolonged storage (48 h or longer) during the non-breeding seasons. Cooled sperm of warmblood stallions collected during the breeding season was characterized by higher initial quality than the sperm collected during the non-breeding season. However, sperm sampled during the non-breeding season appeared to be more resistant to cold shock, which increases their suitability for cold storage at 5 °C. Stallion sperm sampled in both seasons were characterized by similar suitability for liquid storage. Further research is needed to assess the fertilizing capacity of stored sperm. Full article

The present study was designed to investigate the potential role of inhibin immunization on plasma hormone concentration and testicular histoarchitecture of Dezhou donkeys in the nonbreeding season (November–February). For this purpose, adult Dezhou donkeys (n = 30) were equally divided into groups A, B, and C. Group A was actively immunized with 3 mg inhibin, group B with (1.5 mg), and group C was immunized with Bovine serum albumin (BSA) and served as a control. All animals in groups A and B were given a primary dose of inhibin (INH) antigen, i.e., 3 mg and 1.5 mg on day 1, followed by a booster dose on the 23rd day of the experiment. Blood samples were collected on the 21st, 28th, 34th, and 40th days of the experiment. Primary and booster INH immunization (3 mg and 1.5 mg) slightly elevated the plasma hormone concentrations of FSH, LH, AMH, and Activin A. The number of spermatogonia was significantly higher in group A as compared to group C on the 28th day of the experiment. Inhibin immunization also caused apoptosis in testicular histoarchitecture. In conclusion, Inhibin immunization can potentially improve the reproductive efficiency of Dezhou donkeys in a nonbreeding season by elevating plasma hormone concentrations of FSH, LH, AMH, and Activin A. Full article

Background: Dopamine (DA) is an important neurotransmitter that is widely present in the central nervous system. DA plays a crucial regulatory role in mammalian emotion, endocrine function, and reproduction through the activation of dopamine receptors. We compared the transcriptomes of hypothalamic tissues from Kazakh sheep during the nonbreeding season of anoestrus and during the nutrient-induced nonbreeding season of oestrus. Our research findings suggest that the dopamine receptor D1 (DRD1) gene may be a candidate gene for the regulation of sheep oestrus. However, the underlying mechanism through which DRD1 regulates sheep oestrus is still poorly understood. Methods: In the present study, the expression of DRD1 mRNA in the hypothalamus of oestrous Kazakh sheep was significantly greater than that in the anoestrous phase. Immunohistochemical staining revealed that DRD1 was more widely expressed in hypothalamic tissue and was more highly expressed during oestrus than during anoestrus. Hypothalamic neuron experiments further indicated that DRD1 affects the expression of GnRH through dopamine synapses and calcium signalling pathways. Results: moreover, the overexpression of the DRD1 gene promoted the secretion of GnRH, while knocking down the DRD1 gene reduced the secretion of GnRH. Conclusions: The present study revealed that the DRD1 gene plays a crucial regulatory role in the secretion of the hormone GnRH in the hypothalamus of Kazakh sheep. Full article

Off-season breeding is a method of encouraging animals through manual intervention to reproduce during the non-breeding season. The egg-laying period of the Zhedong white goose usually starts from September and ends in April of the following year. During the summer months from May to August, with long daylight hours and high temperatures, the white geese rest and do not lay eggs. This study explored the effects of off-season breeding on egg production performance, serum biochemical indicators, and hormone secretion in Zhedong white goose. The experiment was divided into normal breeding and off-seasonal breeding. The results suggested that the peak laying period lasted 3 months, and egg production was 15.62% higher than that in the control group in the off-season breeding group. The off-season breeding group had a 4.13% higher egg fertilization rate in November (laying period) than the control group, and the hatching rate of hatched eggs and fertilized eggs in the peak laying period was 2.77% and 2.3% higher, respectively, than the control group. The experimental group showed significantly higher serum P, ALB (albumin), TG (triglyceride), and TC (total cholesterol) levels; serum AST (glutamic oxalacetic transaminase) activity; and CREA (creatinine) and BUN (blood urea nitrogen) levels than the control group at different time points. The serum LH (luteinizing hormone), FSH (follicle-stimulating hormone), P4 (progesterone), and E2 (estradiol) levels were significantly higher in the off-season breeding group than in the control group. The serum T3 (triiodothyronine) and T4 (Tetraiodothyronine) levels were significantly higher in the off-season breeding group than in the control group at different points in the breeding cycle. The control group showed a significantly higher gene expression of GnRH (gonadotropin releasing hormone) in the hypothalamus; GnRH, FSH, and LH in the pituitary; and GnRH in the ovary and significantly lower gene expression of VIP (vasoactine intestinal peptide) and PRL (prolactin) in the pituitary than the off-season breeding group. Thus, the off-season breeding of Zhedong white geese may prolong the peak laying period and improve egg production performance, thus enhancing the economic benefits of goose breeding. Full article

Follicle development in dairy goats is lower after induced estrus during the non-breeding season, reducing conception rates and challenging year-round milk supply. This study investigated follicle development during the breeding and non-breeding seasons and explored molecular mechanisms for variations in the proportions of follicles of different sizes using ovarian RNA-seq and in vitro experiments. Induced estrus during the non-breeding season used a simulated breeding season short photoperiod and male effect methods, while the male effect method was used during the breeding season. This study identified an increase in follicle size during the breeding season and performed RNA-seq on ovaries to explore the underlying causes. The RNA-seq analysis elucidated pathways associated with cellular and hormonal metabolism and identified adenylyl cyclase 5 (ADCY5) as a key differentially expressed gene. In vitro experiments demonstrated that interfering with ADCY5 in ovarian granulosa cells (GCs) reduced steroid synthesis. Conversely, the overexpression of ADCY5 increased steroid synthesis. ADCY5 affects the biological function of GCs and consequently influences follicle development through the cAMP-response element binding protein (CREB) and p38 mitogen-activated protein kinase phosphorylation (MAPK) pathways. Overall, our findings demonstrate that follicle development in dairy goats differs between the breeding and non-breeding seasons and that the differential expression levels of the ADCY5 gene contribute to this discrepancy. Full article

Commonly in seasonal breeding animals, testicular development is inhibited prior to Sertoli cell maturation when environmental conditions become unfavorable, with recovery occurring once conditions improve. However, the precise molecular mechanisms governing this process remain unclear. We investigated the role of androgen receptor (AR) in the seasonal regulation of testicular development in a wild population of Rattus norvegicus caraco, a subspecies of brown rats in Northeast China residing in high-latitude regions, known for its seasonal reproductive patterns. Our results revealed a significant increase in Ar mRNA expression in wild rats with small testes less than 0.2 g and body weights ranging between 80 and 100 g during the nonbreeding season. Further examinations of Ar expression in the testicular development of R. n. caraco in the laboratory under different day lengths and temperatures that simulating breeding and nonbreeding seasons suggest that the maturation of Sertoli cells depends on the upregulation of Ar expression around a testis weight of 0.07–0.18 g, regardless of age and conditions, synchronously accompanying the initiation of the meiotic phase. When Ar expression was suppressed, testicular development was impeded around the stage of Sertoli cell maturation, resulting in decreased spermatogenesis and hindered growth in testis weight. Our findings elucidate how animals control the seasonal inhibition and subsequent recovery of testicular development by regulating Ar expression in R. n. caraco. Full article