DISSERTATION RESEARCH: An empirical test of species range limit evolution using the world's largest amphibian invasion

入侵物种是全球生物多样性丧失的主要驱动因素之一。海蟾蜍（Rhinella marina）被列入国际自然保护联盟（www.issg.org）公布的100个世界上最严重的外来入侵物种名单。这种大型的新热带蟾蜍已经入侵了全球40多个国家，并在许多方面对当地生态系统造成了不利影响。最大的，也可以说是最具破坏性的甘蔗蟾蜍入侵地点在澳大利亚。在那里，甘蔗蟾蜍作为一种新的有毒猎物，无脊椎动物和小型脊椎动物的捕食者，以及本地青蛙的竞争对手，已经危及了许多本地野生动物物种。这项研究将揭示哪些环境因素和进化过程促成了蔗蜍非常成功地入侵澳大利亚。这一知识将有助于土地管理者实施控制措施，保护本地物种免受甘蔗蟾蜍的侵害，并有可能限制甘蔗蟾蜍入侵的总体程度。此外，物种的入侵也提供了独特的自然实验，尽管是不幸的，以阐明控制物种地理范围限制的过程。了解物种范围限制的机制是生态学和进化领域的长期目标。鉴于全球气候变化可能使世界上许多地区的地理范围发生变化，这一事实变得紧迫起来。年代的物种。甘蔗蟾蜍是调查物种范围限制的理想选择，因为自1935年被有意引入澳大利亚以来，它们的入侵历史就有非常充分的记录。反过来，这使得基于景观-分散关系的未来入侵预测模型可以用实际入侵的历史数据进行验证。甘蔗蟾蜍在澳大利亚也有稳定和积极扩张的范围边缘，这为比较地理复制区域的范围限制和扩张提供了一个独特的机会。甘蔗蟾蜍对澳大利亚的入侵将通过结合景观遗传和基因组分析以及控制实验室饲养实验进行调查。蔗蜍的扩散模式将与关键的景观因素相关联，以确定哪些栖息地限制和/或促进蔗蜍在澳大利亚的移动。一项基因组研究也将揭示基因组中可能有助于蔗蜍成功入侵的推定适应性区域。结合实验室饲养实验，这项工作将为适应在主要地理范围扩展中的作用提供基因型和表型测试。总的来说，这项工作将为物种范围限制的主要生态和进化理论提供罕见的经验检验，此外还将为帮助控制臭名昭著的全球入侵者提供有用的信息。

Invasive species are one of the key drivers behind the global loss of biodiversity. The cane toad (Rhinella marina) is on the 100 World's Worst Invasive Alien Species list maintained by the International Union for the Conservation of Nature (www.issg.org). This large, Neotropical toad has invaded over 40 countries worldwide and has detrimentally impacted native ecosystems in many ways. The largest, and arguably most damaging, cane toad invasion site is in Australia. There, cane toads have imperiled numerous native wildlife species through their effects as novel toxic prey items, predators of invertebrates and small vertebrates, and competitors with native frogs. This study will reveal which environmental factors and evolutionary processes are contributing to the cane toad's extraordinarily successful invasion of Australia. This knowledge will help land managers implement control measures to protect native species from cane toads, as well as potentially limit the overall extent of the invasion. Moreover, species' invasions also provide unique, albeit unfortunate, natural experiments for elucidating the processes that control species' geographic range limits. Understanding the mechanisms underlying species' range limits is a longstanding goal in the fields of ecology and evolution. It has become urgent in light of the fact that global climate change may necessitate geographic range shifts for many of the world?s species. Cane toads are ideally-suited to investigate species' range limits because have an extraordinarily well-documented history of invasion since their deliberate introduction to Australia in 1935. In turn, this allows predictive models of their future invasion based on landscape-dispersal relationships to be validated with historical data from the actual invasion. Cane toads also have both stable and actively-expanding range edges across Australia, providing a unique opportunity to compare range limits versus expansion in geographically-replicated areas. The cane toad's invasion of Australia will be investigated using a combination of landscape genetic and genomic analyses with controlled laboratory rearing experiments. Cane toad dispersal patterns will be correlated with key landscape factors to determine which habitats restrict and/or enhance cane toad movement throughout Australia. A genomic study will also reveal putatively adaptive regions of the genome that may be contributing to the cane toad's invasion success. In combination with laboratory rearing experiments, this work will provide genotypic and phenotypic tests of the role of adaptation in a major geographic range expansion. Overall this work will provide a rare empirical test of the leading ecological and evolutionary theories for species' range limits, in addition to useful information to help control a notorious worldwide invader.