extinction

灭绝
  • 文章类型: Journal Article
    在本文中,我们考虑了具有修改Leslie-Gower的随机两物种捕食者-食饵系统。同时,我们假设捕食者中发生了狩猎合作。通过运用IT公式构造一个合适的Lyapunov函数,我们首先证明,对于任何给定的正初始值,都有一个唯一的全局正解。此外,基于切比雪夫不等式,讨论了随机最终有界性和随机持久性。然后,在某些条件下,我们证明了系统的均值和灭绝的持久性。最后,我们通过数值模拟验证了我们的结果。
    In this paper, we consider a stochastic two-species predator-prey system with modified Leslie-Gower. Meanwhile, we assume that hunting cooperation occurs in the predators. By using Itô formula and constructing a proper Lyapunov function, we first show that there is a unique global positive solution for any given positive initial value. Furthermore, based on Chebyshev inequality, the stochastic ultimate boundedness and stochastic permanence are discussed. Then, under some conditions, we prove the persistence in mean and extinction of system. Finally, we verify our results by numerical simulations.
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  • 文章类型: Journal Article
    种间竞争会阻碍种群进化适应非生物环境,特别是通过减少人口规模和生态位空间;竞争能力和进化适应之间可能会产生反馈。在这里,我们研究了两种模式细菌的种群,大肠杆菌和荧光假单胞菌,在三个温度下以单种培养和共培养方式进化了大约2400代。这两个物种在温度梯度的共培养中显示出竞争优势的逆转。在竞争中占主导地位的共文化群体显示出与单一文化相同的健身增益。然而,与单种培养相比,共培养中竞争性较差的种群显示出有限的非生物适应性。共培养中的劣等群体也更有可能进化出较弱的种间竞争能力,或者灭绝。可能的竞争能力-适应能力反馈可能对人口持久性产生至关重要的影响。
    Interspecific competition can hinder populations from evolutionarily adapting to abiotic environments, particularly by reducing population size and niche space; and feedback may arise between competitive ability and evolutionary adaptation. Here we studied populations of two model bacterial species, Escherichia coli and Pseudomonas fluorescens, that evolved in monocultures and cocultures for approximately 2400 generations at three temperatures. The two species showed a reversal in competitive dominance in cocultures along the temperature gradient. Populations from cocultures where they had been competitively dominant showed the same magnitude of fitness gain as those in monocultures. However, competitively inferior populations in cocultures showed limited abiotic adaptation compared with those in monocultures. The inferior populations in cocultures were also more likely to evolve weaker interspecific competitive ability, or go extinct. The possible competitive ability-adaptation feedback may have crucial consequences for population persistence.
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  • 文章类型: Journal Article
    高克隆草通常具有氮(N)富集的竞争优势。然而,目前尚不清楚身高是来自植物还是生殖模块。此外,尚不清楚植物或生殖系统的高度是否调节灭绝和定殖的可能性,并决定物种多样性。在这项研究中,对克隆草的影响在田间试验中进行了研究,采用两种频率(每年两次与每月)在温带草原中以9个氮添加率穿越,中国。我们发现氮的添加降低了物种频率,增加了灭绝概率,但并没有改变物种定殖的概率。低频率的N添加降低了物种频率和定殖概率,但增加了灭绝的可能性。此外,我们发现,物种繁殖高度是预测富氮条件下克隆草灭绝概率的最佳指标。低频率的氮添加可能高估了氮沉积对克隆草多样性的负面影响。表明较高的N添加频率更适合评估N沉积的生态效应。总的来说,这项研究表明,在富氮环境下,生殖高度与克隆物种灭绝概率有关。
    Tall clonal grasses commonly display competitive advantages with nitrogen (N) enrichment. However, it is currently unknown whether the height is derived from the vegetative or reproductive module. Moreover, it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization, and determines species diversity. In this study, the impacts on clonal grasses were studied in a field experiment employing two frequencies (twice a year vs. monthly) crossing with nine N addition rates in a temperate grassland, China. We found that the N addition decreased species frequency and increased extinction probability, but did not change the species colonization probability. A low frequency of N addition decreased species frequency and colonization probability, but increased extinction probability. Moreover, we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions. The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity, suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition. Overall, this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.
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  • 文章类型: Journal Article
    现存的旧世界骆驼(骆驼属)几千年来为东西方之间的经济和文化交流做出了贡献。1,2尽管出土了许多遗骸,3,4,5我们既不知道在现存的骆驼物种2,6,7之间观察到的普遍杂交是否也发生在已灭绝的谱系和现存的骆驼物种的祖先之间,也不知道为什么某些种群灭绝而另一些种群幸存下来。为了调查这些问题,我们从已灭绝的双峰骆驼物种中获得了古基因组和稳定同位素数据,CamelusKnoblochi.我们发现在线粒体系统发育中,所有C.knoblochi都形成了一个共生的群体,在现代的多样性中筑巢,野生双峰骆驼(Camelusferus)。相比之下,在核水平上,它们与野生和驯化的(Camelusbactrianus)双峰骆驼明显不同。此外,三种骆驼的发散模式近似为三分叉,因为最常见的拓扑仅比其他两种可能的拓扑稍微频繁一些。这种mito核系统发育不一致可能是由于所有三个物种之间的种间基因流动引起的,表明种间杂交并非现代骆驼独有,而是在骆驼属的进化史上反复出现的现象。这些结果表明,当仅考虑来自现代物种的数据时,旧世界骆驼进化史的基因组复杂性被低估了。最后,我们发现C.knoblochi种群在最后一次冰川最大值之前开始下降,通过整合古生态证据和稳定同位素数据,这可能是由于未能适应不断变化的环境。
    Extant Old World camels (genus Camelus) contributed to the economic and cultural exchanges between the East and West for thousands of years.1,2 Although many remains have been unearthed,3,4,5 we know neither whether the prevalent hybridization observed between extant Camelus species2,6,7 also occurred between extinct lineages and the ancestors of extant Camelus species nor why some populations became extinct while others survived. To investigate these questions, we generated paleogenomic and stable isotope data from an extinct two-humped camel species, Camelus knoblochi. We find that in the mitochondrial phylogeny, all C. knoblochi form a paraphyletic group that nests within the diversity of modern, wild two-humped camels (Camelus ferus). In contrast, they are clearly distinguished from both wild and domesticated (Camelus bactrianus) two-humped camels on the nuclear level. Moreover, the divergence pattern of the three camel species approximates a trifurcation, because the most common topology is only slightly more frequent than the two other possible topologies. This mito-nuclear phylogenetic discordance likely arose due to interspecific gene flow between all three species, suggesting that interspecific hybridization is not exclusive to modern camels but a recurrent phenomenon throughout the evolutionary history of the genus Camelus. These results suggest that the genomic complexity of Old World camels\' evolutionary history is underestimated when considering data from only modern species. Finally, we find that C. knoblochi populations began declining prior to the last glacial maximum and, by integrating palaeoecological evidence and stable isotope data, suggest that this was likely due to failure to adapt to a changing environment.
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  • 文章类型: Journal Article
    传染病在人类历史上一直是一股塑造力量,需要全面了解它们的动态。本研究引入了一个整合流行病学和进化动力学的共同进化模型。利用微分方程组,该模型代表了易感人群之间的相互作用,感染,并恢复了祖先和进化病毒株的种群。方法严谨,验证了模型的存在性和唯一性,它既适用于确定性的情况,也适用于随机的情况。已经采用了无数的图形技术来阐明模型的动力学。除了其理论贡献,该模型是公共卫生战略的重要工具,特别是在病毒突变危及现有干预措施的情况下预测未来的疫情。
    Infectious diseases have long been a shaping force in human history, necessitating a comprehensive understanding of their dynamics. This study introduces a co-evolution model that integrates both epidemiological and evolutionary dynamics. Utilizing a system of differential equations, the model represents the interactions among susceptible, infected, and recovered populations for both ancestral and evolved viral strains. Methodologically rigorous, the model\'s existence and uniqueness have been verified, and it accommodates both deterministic and stochastic cases. A myriad of graphical techniques have been employed to elucidate the model\'s dynamics. Beyond its theoretical contributions, this model serves as a critical instrument for public health strategy, particularly predicting future outbreaks in scenarios where viral mutations compromise existing interventions.
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  • 文章类型: Journal Article
    claustrum(CLA),岛叶皮层和纹状体之间的皮层下区域,神经支配哺乳动物大脑的几乎所有皮质区域。越来越多的证据表明,CLA参与了许多大脑功能,包括记忆,认知,和应激反应。有人认为,CLA的功能障碍或功能障碍可能是某些脑部疾病的病理。包括压力引起的抑郁和焦虑。然而,CLA在恐惧记忆和焦虑症中的作用仍未得到充分研究.
    我们使用听觉提示的恐惧记忆和焦虑样行为评估了CLA神经毒性病变的影响。
    我们发现前CLA(aCLA)而不是后CLA(pCLA)的损伤在恐惧条件下减弱了恐惧恢复,促进灭绝,并在消光保持试验期间降低冻结水平。在灭绝保留测试期间,aCLA而不是pCLA的学习后病变促进了恐惧灭绝并减弱了冻结行为。aCLA或pCLA的病变不会影响通过开放场测试和高架迷宫测试评估的焦虑样行为。
    这些数据表明,aCLA而不是pCLA参与了恐惧记忆和灭绝。未来的研究需要进一步调查与恐惧条件有关的aCLA子区域的解剖和功能连接,这将加深我们对CLA功能的理解。
    UNASSIGNED: The claustrum (CLA), a subcortical area between the insular cortex and striatum, innervates almost all cortical regions of the mammalian brain. There is growing evidence that CLA participates in many brain functions, including memory, cognition, and stress response. It is proposed that dysfunction or malfunction of the CLA might be the pathology of some brain diseases, including stress-induced depression and anxiety. However, the role of the CLA in fear memory and anxiety disorders remains largely understudied.
    UNASSIGNED: We evaluated the influences of neurotoxic lesions of the CLA using auditory-cued fear memory and anxiety-like behaviors in rats.
    UNASSIGNED: We found that lesions of anterior CLA (aCLA) but not posterior CLA (pCLA) before fear conditioning attenuated fear retrieval, facilitated extinction, and reduced freezing levels during the extinction retention test. Post-learning lesions of aCLA but not pCLA facilitated fear extinction and attenuated freezing behavior during the extinction retention test. Lesions of aCLA or pCLA did not affect anxiety-like behaviors evaluated by the open field test and elevated plus-maze test.
    UNASSIGNED: These data suggested that aCLA but not pCLA was involved in fear memory and extinction. Future studies are needed to further investigate the anatomical and functional connections of aCLA subareas that are involved in fear conditioning, which will deepen our understanding of CLA functions.
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  • 文章类型: Journal Article
    在本文中,我们提出并分析了一个非自治模型,该模型描述了规模结构化消费者与非结构化资源交互的动态。我们基于比较原理,使用单调方法证明了模型解的存在性和唯一性。我们通过上下解技术得出模型参数的条件,这些条件会导致种群的持久性和灭绝。我们通过数值模拟对理论结果进行了验证和补充。
    In this paper, we propose and analyze a nonautonomous model that describes the dynamics of a size-structured consumer interacting with an unstructured resource. We prove the existence and uniqueness of the solution of the model using the monotone method based on a comparison principle. We derive conditions on the model parameters that result in persistence and extinction of the population via the upper-lower solution technique. We verify and complement the theoretical results through numerical simulations.
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  • 文章类型: Journal Article
    厌恶图像代表了厌恶相关疾病的潜在病理机制。然而,关于厌恶是否可以以厌恶引起的心理意象作为无条件刺激(美国)为条件,这仍然存在争议。因此,我们使用条件性学习范式结合事件相关电位(ERP)分析对35名健康大学生进行了研究.结果表明,最初的中性面孔(条件刺激,CS+)变得更加厌恶,不愉快,在与令人厌恶的意象(令人厌恶的CS+)配对后被唤醒,与中性(中性CS+)和无(CS-)图像配对相比。此外,我们观察到基于心理意象的厌恶条件对灭绝具有抵抗力。尽管在采集过程中,厌恶CS引起的P3和正电位幅度比CS-更大,厌恶CS+和中性CS+之间没有发现显著差异,表明自我报告和神经生理反应之间的分离。未来的研究可能还会获得面部肌电图作为条件性厌恶的内隐指标。这项研究提供了第一个神经生物学证据,证明联想厌恶学习可以在没有厌恶的物理刺激的情况下发生。与理解厌恶相关的疾病如何在没有外部感知厌恶经验的情况下表现或恶化有关,例如强迫症(OCD)。
    Disgust imagery represents a potential pathological mechanism for disgust-related disorders. However, it remains controversial as to whether disgust can be conditioned with disgust-evoking mental imagery serving as the unconditioned stimulus (US). Therefore, we examined this using a conditioned learning paradigm in combination with event-related potential (ERP) analysis in 35 healthy college students. The results indicated that the initial neutral face (conditioned stimulus, CS+) became more disgust-evoking, unpleasant, and arousing after pairing with disgust-evoking imagery (disgust CS+), compared to pairing with neutral (neutral CS+) and no (CS-) imagery. Moreover, we observed that mental imagery-based disgust conditioning was resistant to extinction. While the disgust CS + evoked larger P3 and late positive potential amplitudes than CS- during acquisition, no significant differences were found between disgust CS+ and neutral CS+, indicating a dissociation between self-reported and neurophysiological responses. Future studies may additionally acquire facial EMG as an implicit index of conditioned disgust. This study provides the first neurobiological evidence that associative disgust learning can occur without aversive physical stimuli, with implications for understanding how disgust-related disorders may manifest or deteriorate without external perceptual aversive experiences, such as in obsessive-compulsive disorder (OCD).
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  • 文章类型: Journal Article
    腺苷酸环化酶1(AC1)是一种选择性的ACs亚型,在神经元中选择性表达。AC1的激活是活性依赖性的,AC1在导致慢性疼痛和相关情绪障碍的皮质兴奋中起重要作用。先前的研究报道,人类使用的NB001(hNB001,一种选择性AC1抑制剂)在不同的慢性疼痛动物模型中产生了镇痛作用。然而,hNB001对学习和记忆的潜在影响研究较少。在本研究中,我们发现hNB001既不影响痕量恐惧的诱导也不影响其表达,但选择性地增强了老年小鼠灭绝期间的再学习能力。相比之下,HNB001的相同应用没有影响最近,远程听觉恐惧记忆,或在成年或成年小鼠中远程恐惧灭绝。此外,单次或连续30天口服hNB001不影响急性伤害性反应,运动功能,或成年或老年小鼠的焦虑样行为。我们的结果与先前的发现一致,即抑制AC1不影响一般感觉,情感,和成年小鼠的运动功能,并提供强有力的证据表明,抑制AC1的活性可能对老年小鼠的某些形式的学习和记忆有益。
    Adenylyl cyclase 1 (AC1) is a selective subtype of ACs, which is selectively expressed in neurons. The activation of AC1 is activity-dependent, and AC1 plays an important role in cortical excitation that contributes to chronic pain and related emotional disorders. Previous studies have reported that human-used NB001 (hNB001, a selective AC1 inhibitor) produced analgesic effects in different animal models of chronic pain. However, the potential effects of hNB001 on learning and memory have been less investigated. In the present study, we found that hNB001 affected neither the induction nor the expression of trace fear, but selectively enhanced the relearning ability during the extinction in aged mice. By contrast, the same application of hNB001 did not affect recent, remote auditory fear memory, or remote fear extinction in either adult or aged mice. Furthermore, a single or consecutive 30-day oral administration of hNB001 did not affect acute nociceptive response, motor function, or anxiety-like behavior in either adult or aged mice. Our results are consistent with previous findings that inhibition of AC1 did not affect general sensory, emotional, and motor functions in adult mice, and provide strong evidence that inhibiting the activity of AC1 may be beneficial for certain forms of learning and memory in aged mice.
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  • 文章类型: Journal Article
    人类活动和气候变化影响生物多样性并导致物种范围变化,收缩,和扩张。全球范围内,人类活动和气候变化已经成为对生物多样性的持续威胁,导致大约68%的~522灵长类物种面临灭绝的威胁。这里,我们使用了栖息地适宜性模型和人口密度的综合数据,国内生产总值(GDP),道路建设,归一化植被指数(NDVI),保护区(PA)的位置,和气候变化来预测中国26种灵长类动物的分布范围和丰富度的潜在变化。我们的结果表明,PAs和NDVI对灵长类动物的分布都有积极的影响。随着人为压力的增加,物种范围仅限于高植被覆盖区域和被2.7-4.5km缓冲区包围的PA,以及距PA最近边缘至少0.1-0.5km的PA核心区域。国内生产总值低于中国全国平均水平10万元的地区被发现生态脆弱,这对灵长类动物的分布产生了负面影响。温度和降水的变化也是灵长类动物种类减少的重要原因。在未来30-50年气候变化的预期影响下,我们发现,非常适合灵长类动物的栖息地将继续减少,物种将被限制在其当前范围内更小,更外围的部分。预计灵长类动物多样性高的地区将减少3至7种。我们建议立即采取行动,包括扩大中国国家公园计划,生态保护红线计划,和天然林保护计划,以及更强有力的国家政策,为邻近灵长类动物的当地社区的人们提供替代/可持续的生计,抵消人为活动和气候变化对灵长类动物生存的有害影响。
    Human activity and climate change affect biodiversity and cause species range shifts, contractions, and expansions. Globally, human activities and climate change have emerged as persistent threats to biodiversity, leading to approximately 68% of the ~522 primate species being threatened with extinction. Here, we used habitat suitability models and integrated data on human population density, gross domestic product (GDP), road construction, the normalized difference vegetation index (NDVI), the location of protected areas (PAs), and climate change to predict potential changes in the distributional range and richness of 26 China\'s primate species. Our results indicate that both PAs and NDVI have a positive impact on primate distributions. With increasing anthropogenic pressure, species\' ranges were restricted to areas of high vegetation cover and in PAs surrounded by buffer zones of 2.7-4.5 km and a core area of PAs at least 0.1-0.5 km from the closest edge of the PA. Areas with a GDP below the Chinese national average of 100,000 yuan were found to be ecologically vulnerable, and this had a negative impact on primate distributions. Changes in temperature and precipitation were also significant contributors to a reduction in the range of primate species. Under the expected influence of climate change over the next 30-50 years, we found that highly suitable habitat for primates will continue to decrease and species will be restricted to smaller and more peripheral parts of their current range. Areas of high primate diversity are expected to lose from 3 to 7 species. We recommend that immediate action be taken, including expanding China\'s National Park Program, the Ecological Conservation Redline Program, and the Natural Forest Protection Program, along with a stronger national policy promoting alternative/sustainable livelihoods for people in the local communities adjacent to primate ranges, to offset the detrimental effects of anthropogenic activities and climate change on primate survivorship.
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