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关键驱动因素之一。甘蔗蟾蜍(Rhinella Marina)被列入由国际自然保护联盟(www.issg.org)维护的100种世界最糟糕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，甘蔗蟾蜍作为新的有毒猎物、无脊椎动物和小型脊椎动物的捕食者以及与当地青蛙的竞争对手，已经危及了许多当地野生动物物种。这项研究将揭示哪些环境因素和进化过程有助于甘蔗蟾蜍非常成功地入侵澳大利亚。这一知识将有助于土地管理人员实施控制措施，以保护当地物种免受甘蔗蟾蜍的侵袭，并可能限制入侵的总体范围。此外，物种的入侵也为阐明控制物种地理范围范围的过程提供了独特的、尽管不幸的自然实验。了解物种活动范围限制的机制是生态学和进化论领域的一个长期目标。鉴于全球气候变化可能会导致世界上许多物种--S物种--的地理范围发生变化，这一问题变得紧迫起来。甘蔗蟾蜍非常适合研究物种的活动范围，因为自1935年故意引入澳大利亚以来，它们有非常详细的入侵历史记录。反过来，这使得基于地貌-扩散关系的它们未来入侵的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大活动范围的优势，这提供了一个独特的机会来比较地理复制地区的活动范围限制和扩展。将使用景观遗传和基因组分析与受控实验室饲养实验相结合的方法来调查甘蔗蟾蜍对澳大利亚的入侵。甘蔗蟾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/或促进整个澳大利亚的甘蔗蟾蜍活动。一项基因组研究还将揭示基因组的假定适应性区域，这些区域可能有助于甘蔗蟾蜍入侵成功。结合实验室饲养实验，这项工作将提供对适应在主要地理范围扩大中的作用的基因型和表型测试。总体而言，这项工作除了提供有用的信息来帮助控制臭名昭著的世界性入侵者外，还将为物种范围限制的领先生态和进化理论提供罕见的经验检验。

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.