Ecological and Genetic Determinants of the Expansion of Grey Squirrel Populations in Italy and Britain

意大利和英国灰松鼠种群扩张的生态和遗传决定因素

• 批准号: NE/G011842/1
• 金额: $ 10.95万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG011842%2F1
• 关键词: Ecological; Genetic; Determinants; Expansion; Grey

Invasive species are a major threat to global biodiversity and are widely associated with human introductions. The American Grey squirrel, following multiple introductions into Europe, has had a massive impact on native red squirrel populations in the UK, Italy and Ireland, causing major shifts in the red squirrel's range. In addition, grey squirrels in the UK have had an important impact on agroindustry by debarking trees in plantations. The species is seen as likely to disperse widely from Italy, displacing red squirrels and harming agroindustry across Europe. Under a worst-case scenario, models predict the expansion of Italian grey squirrels into France and Switzerland within 20-30 years. Hypotheses. However, models of grey squirrel expansion have been parameterized approximately, and Italian, British and Irish populations of grey squirrels have expanded at substantially different rates for unknown reasons. These populations originated from very different numbers of introduced individuals (and hence have different genetic diversity), and are subject to different ecologies. Reduced red squirrel body mass and recruitment has been linked to the presence of greys. Associated declines in red populations due to competition with greys are accentuated by a poxvirus disease lethal to reds, but carried by and not harmful to greys. The poxvirus is present in the UK and absent from Italy, suggesting the hypothesis that UK expansion is faster than in Italy because poxvirus kills local reds, eliminating a competitor that otherwise would slow the greys' advance. However, competition could well be asymmetrical; it has not been demonstrated that competition with reds reduces the vital rates of greys. An alternative hypothesis is that low genetic variation and inbreeding depression slows the growth of the Italian grey squirrel population, relative to British populations. In a large study of invasive species, founder population size was identified as a key factor in invasive success; the founder population sizes of grey squirrels in the UK were much larger than those in Italy. The main goal of the research is to test these hypotheses, restated here: 1) Different expansion rates of grey squirrels in Italy and Britain are due primarily to different competitive environments faced by the greys, partly because competition from reds is eliminated or reduced by pox virus in the UK. 2) Different expansion rates are due primarily to different levels of genetic diversity in the grey squirrel populations in Italy and the UK. The relative contributions of both factors to expansion rates will be assessed. Results may have major management implications. Methods. Methods will include microsatellite analysis of DNA samples from Italian and British squirrels, and trapping programs and other field work at two Italian and two British sites, one in each country with greys only, and one with greys and reds. Management implications. If expansion rate of grey squirrels in Italy is strongly limited by low genetic diversity, it will be important to prevent the three separate Italian populations from merging and thereby increasing diversity and speeding expansion rate. This could be accomplished by eradicating the two populations which are still small enough for eradication. It would also be essential to prevent all further introductions, even of a few squirrels. If expansion rate is limited by competition from red squirrels, it will be essential to prevent the introduction of poxvirus into Italy. Model-based estimates of expansion patterns are an important tool for conservation policy. The proposed research may help to parameterize models more precisely and increase effectiveness of future conservation actions.

入侵物种是对全球生物多样性的主要威胁，与人类的引入密切相关。美国灰松鼠在多次引入欧洲后，对英国，意大利和爱尔兰的本地红松鼠种群产生了巨大的影响，导致红松鼠的范围发生了重大变化。此外，英国的灰松鼠通过在种植园中剥皮对农业工业产生了重要影响。该物种被认为可能会从意大利广泛传播，取代红松鼠并危害整个欧洲的农业。在最坏的情况下，模型预测意大利灰松鼠将在20-30年内扩展到法国和瑞士。假设。然而，灰松鼠扩张的模型已经被近似参数化，意大利，英国和爱尔兰的灰松鼠种群由于未知的原因以不同的速度扩张。这些种群起源于不同数量的引进个体（因此具有不同的遗传多样性），并受到不同的生态系统的影响。减少红松鼠的体重和招聘已与灰色的存在。由于与灰人的竞争，红人种群的相关下降被一种对红人致命但对灰人无害的痘病毒病加剧。痘病毒存在于英国，而不存在于意大利，这表明了这样一种假设，即英国的扩张速度比意大利快，因为痘病毒杀死了当地的红细胞，消除了一个竞争对手，否则会减缓灰细胞的进展。然而，竞争很可能是不对称的;没有证据表明与红细胞竞争会降低灰细胞的生命率。另一种假设是，低遗传变异和近交衰退减缓了意大利灰松鼠种群的增长，相对于英国种群。在一项大型的入侵物种研究中，创始人种群规模被认为是入侵成功的关键因素;英国灰松鼠的创始人种群规模远大于意大利。这项研究的主要目的是检验这些假设，在这里重申：1）灰松鼠在意大利和英国的不同扩张速度主要是由于灰松鼠面临的不同竞争环境，部分原因是来自红松鼠的竞争被英国的痘病毒消除或减少。2)不同的扩张率主要是由于在意大利和英国的灰松鼠种群的遗传多样性水平不同。将评估这两个因素对膨胀率的相对影响。结果可能会产生重大的管理影响。方法.方法将包括意大利和英国松鼠DNA样本的微卫星分析，以及在两个意大利和两个英国地点的诱捕计划和其他实地工作，每个国家一个只有灰色，一个有灰色和红色。管理影响。如果灰松鼠在意大利的扩张速度受到低遗传多样性的强烈限制，那么防止三个独立的意大利种群合并从而增加多样性和加速扩张速度将是重要的。这可以通过消灭两个种群来实现，这两个种群仍然很小，足以消灭。同样重要的是，要防止一切进一步的引进，即使是几只松鼠。如果扩张速度受到来自红松鼠的竞争的限制，那么必须防止痘病毒传入意大利。基于模型的扩张模式的估计是保护政策的重要工具。建议的研究可能有助于更精确地参数化模型，并提高未来保护行动的有效性。