摘要: The population regulation of animals depends on fertility and survivorship. Hunting can affect population growth through changes in reproduction and survivorship. Understanding these changes in vital rates is crucial for the control of invasive mammals. With the objective to assess the influence of different population removal pressures on the finite population growth rate (lambda) of an invasive mammal, this research used demographic data estimated from 922 invasive beavers (Castor canadensis) eradicated from seven areas from Isla Grande de Tierra del Fuego, Argentina. Areas were classified into four removal pressures: higher, high-intermediate, low-intermediate, and lower removal pressure. The hypothesis states that the higher removal pressure produces higher population growth and resilience. Leslie matrix models were used to estimate lambda, generation time, damping ratio, stable age distribution, reproductive value, and the sensitivity-elasticity of survivorship and fertility of the females for each removal pressure. The lambda and damping ratio increased with the removal pressure, as expected; the inverse occurred with the generation time. The survivorship of the younger age classes was the most sensitive and elastic vital rate regardless of removal pressure, followed by the breeding onset. The fertility was less relevant on lambda. The beaver population would depend more on the survival of kits, 1-year-olds, and subadults, than the number of offspring produced. A management strategy is proposed focusing on affecting the survivorship of younger age classes, eliminating first the adult animals and then the younger beavers.

摘要: In mammals, temporal and spatial variation in appendage sizes within and among species may be driven by variations in ambient temperature and allometric scaling. Here, we use two decades of morphological data on three rodent species distributed across vast latitudinal gradients in China to estimate temporal and spatial trends of tail, hind-foot, and ear lengths. Further, we test 14 climate variables to identify the critical drivers of these trends and use structural equation modeling (SEM) to analyze whether the effects of climate variables on the appendage lengths are direct or indirect, via effects on body length. Relative to body length, and in contradiction to Allen's rule, all appendage lengths remained unchanged over time and across space. By contrast, absolute appendage lengths increased in one species (Apodemus agrarius) over time and in two species (A. agrarius and Rattus norvegicus) across space; and most of the appendage lengths in the two species were associated with annual mean minimum temperature in the year preceding capture (PreAnnMinTemp). The SEM results suggest that PreAnnMinTemp affected absolute appendage lengths indirectly through body length. In addition, except for tail length in two species and both hind-foot and ear length in one species, absolute appendage lengths scaled allometrically with body length. These results suggest that the distinct temperature-appendage-length patterns among and within species arise from species-specific temperature sensitivities and appendage-specific ontogenetic rates and functions.

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摘要: The Gansu zokor (Eospalax cansus), a subterranean rodent endemic to the Loess Plateau of China, exhibits remarkable adaptability to hypoxic environments. While gut microbiota are known to regulate lipid metabolism through bile acid (BA) pathways, this phenomenon has not been investigated in subterranean rodents exposed to hypoxia. This study employed 16SrRNA sequencing, targeted analysis of BA metabolites in colonic contents, and assessments of BA and lipid metabolites alongside molecular analyses in the liver and ileum under conditions of acute and chronic hypoxia in Gansu zokors. The results revealed that hypoxia altered the composition of gut microbiota and BA pools in Gansu zokors. Hypoxia-induced changes increased the abundance of gut microbiota associated with BA metabolism, thereby modulating lipid metabolism via farnesoid X receptor (FXR) signaling in the distal ileum and liver cells. Under acute hypoxia, FXR upregulated lipid synthesis and suppressed fatty acid beta-oxidation by downregulating the carnitine palmitoyl-transferase1A (CPT1A) expression. Conversely, during chronic hypoxia, particularly under long-term exposure, FXR reduced lipid synthesis and enhanced fatty acid beta-oxidation by upregulating acyl-CoA oxidase (ACOX1) expression. In both hypoxic conditions, FXR facilitated lipoprotein metabolism. In summary, this study elucidates that gut microbiota-mediated BA metabolic pathways contribute to the Gansu zokor's ability to maintain lipid metabolic homeostasis and adaptation to hypoxia.

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摘要: This study thoroughly examines biodiversity and aquatic ecosystems across 14 sampled sites within the Shitou River basin by utilizing environmental DNA technology. Through integrated analysis and high-throughput sequencing, the study elucidates a diverse array of biodiversity, encompassing 27 fish species and 341 freshwater benthic macroinvertebrates (FBM) species. Using various biodiversity indices, we found significant differences in diversity and stability across different environments. Regions with more complex habitats had higher species richness and evenness. Further analyses showed complex relationships between diversity metrics for FBM and fish, indicating potential interactions between these groups. The standardized mean score (SMS) was developed to aid in the assessment of water quality. Specifically, SMS scoring revealed that sites STH3, STH4, and STH14 excelled across multiple dimensions, earning an Excellent rating, while site STH12 was rated as Poor due to subpar performance across several metrics. This project not only enhances current understanding regarding aquatic ecological dynamics but also establishes a strong foundation for detailed environmental evaluation and monitoring, aligned with the priorities of contemporary ecological management and caution.

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