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Genetic diversity, environmental stress and emerging infectious disease in conservation.

机译：保护中的遗传多样性，环境压力和新发传染病。

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Emerging infectious diseases have important impacts on agriculture, human health and conservation. Among these, conservation presents unique challenges because it is more difficult to detect, diagnose and treat disease outbreaks in natural populations. Effective disease management for conservation may therefore depend on understanding those factors that can inhibit the colonization or spread of diseases in naive host populations. This study examined the effect of host genetic diversity and environmental stress on the susceptibility of Gila topminnow (Poeciliopsis occidentalis) populations to the bacterial pathogen Listonella (formerly Vibrio ) anguillarum. The Gila topminnow is an endangered fish endemic to parts of Mexico, Arizona and New Mexico, and L. anguillarum is a causative agent of vibriosis, a well-studied septicaemic disease of fish. Controlled, pathogen-exposure experiments and modeling were used to evaluate the role of genetic variation, and controlled, pathogen-exposure experiments were used to assess the vulnerability of Gila topminnows to vibriosis under fluctuating salinity and temperature. Empirical findings failed to support the idea that Gila topminnow populations with greater genetic diversity would suffer less severe outbreaks of vibriosis, and this was consistent whether genetic diversity was assessed using microsatellites or a major histocompatibility complex locus. Model analysis indicated that the effect of genetic diversity on the expected proportion of susceptible hosts was small, and that the direction of the effect depended on assumptions regarding the mechanism of phenotypic expression. Model analysis also indicated that as genetic diversity increased, variation in the expected proportion of susceptible hosts decreased. Thus, natural populations with low levels of genetic variation may be expected to be either entirely resistant or entirely susceptible to a novel pathogen, while populations with greater genetic diversity may have a more consistent, intermediate level of susceptibility to each new pathogen. This result leads to the counterintuitive prediction that genetically diverse populations may be expected to suffer from a greater number of disease outbreaks, and harbor a greater number of endemic pathogens. Empirical results regarding the effects of variation in salinity and temperature on the susceptibility of Gila topminnows to vibriosis indicated that (1) salinity elevation enhanced the infectious efficiency of L. anguillarum on the Gila topminnow, (2) salinity stress increased Gila topminnow susceptibility to vibriosis, and (3) thermal stress did not increase Gila topminnow susceptibility to vibriosis. While the apparent requirement of L. anguillarum for saline conditions suggests that natural populations of the Gila topminnow may be unlikely to be threatened by this particular pathogen, events leading to cumulative, stress-related depression of immunity may leave Gila topminnow populations at an enhanced risk for outbreaks of other diseases, at least temporarily.
机译：新兴传染病对农业，人类健康和保护具有重要影响。其中，养护提出了独特的挑战，因为在自然种群中更难检测，诊断和治疗疾病暴发。因此，有效的疾病保护管理可能取决于了解可以抑制天真的宿主种群中疾病定植或传播的那些因素。这项研究检查了宿主遗传多样性和环境压力对吉拉顶叶now（Poeciliopsis occidentalis）种群对细菌性病原体李氏杆菌（Listonella anguillarum）的敏感性的影响。吉拉（Gila topminnow）是墨西哥，亚利桑那州和新墨西哥州部分地区特有的濒危鱼类，而安圭拉乳杆菌是弧菌病的病原体，弧菌病是一种经过充分研究的鱼类败血症病。受控的病原体暴露实验和建模用于评估遗传变异的作用，而受控的病原体暴露实验用于评估盐度和温度变化下吉拉top小鱼对弧菌的脆弱性。经验发现未能支持这样的想法，即具有更大遗传多样性的吉拉顶级小种群将遭受不太严重的弧菌病暴发，这与是否使用微卫星或主要组织相容性复杂基因座评估遗传多样性是一致的。模型分析表明，遗传多样性对易感宿主的预期比例的影响很小，并且影响的方向取决于有关表型表达机制的假设。模型分析还表明，随着遗传多样性的增加，易感宿主的预期比例的变化减少。因此，可以预期具有低遗传变异水平的自然种群对新病原体完全耐药或完全易感，而具有较高遗传多样性的种群对每种新病原体的敏感性更一致，中等。该结果导致与直觉相反的预测，即可能期望遗传多样性的人群遭受更多的疾病暴发，并拥有更多的地方病原体。关于盐度和温度变化对吉拉顶敏对弧菌易感性的影响的经验结果表明：（1）盐度升高增强了吉氏顶敏诺对虾的感染效率；（2）盐分胁迫增加了吉拉顶敏对弧菌的易感性，和（3）热应激并未增加Gila topminnow对弧菌病的易感性。虽然鳗L对盐碱化的明显要求表明该特定病原体可能不大可能威胁吉拉Topminnow的自然种群，但导致累积的，与压力相关的免疫力下降的事件可能会使吉拉Topminnow的种群处于更高的风险中对于其他疾病的爆发，至少是暂时的。

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