DISSERTATION RESEARCH: Does Transgressive Segregation in Physiological Niche Explain the Rapid Spread of Invasive Genes into a Native Population

重大的快速进化变化是众所周知的，但潜在的机制以及这些变化如何影响生存和繁殖往往不清楚。这个项目将通过调查引进的火蜥蜴物种的成功和地理传播是否是与本地物种杂交的结果来解决快速进化变化的过程。虽然非本地物种的引入被认为会导致快速进化，但人们仍然不清楚这种情况发生的频率、涉及的因素，以及这是否促进了引入物种的成功和传播。有时引进的物种与本地物种杂交，产生可存活的后代，表现出亲本物种中没有的极端特性值。例如，后代可能比亲代物种更大，或者对环境压力的耐受性更强。潜在地，这样的杂交后代可以在竞争中胜过亲本物种，或者在没有被亲本物种占据的新环境中定居。由于杂交产生的极端性状值--超亲分离--在可存活的后代中很少见。然而，当它发生时，后代可以用全新的方式与环境相互作用，导致快速的进化变化。研究人员将研究濒临灭绝的本土物种加州虎蜥蜴和近缘关系密切的引进物种斑蜥之间的基因混合，以检验越级隔离导致本土物种极快进化的假说。数据将揭示生活史、生理和栖息地如何结合在一起，以确定这两个物种重叠和杂交的地区的遗传模式。该项目还包括对本科生和研究生的培训，针对K-12学生的教育计划，以及为保护管理人员举办的讲习班。虎纹盘藻和卡氏盘藻的杂交表现出相对于体型的超越性分离，并且表现出比原生种更广泛的耐热性。然而，我们仍然不知道生态上重要特征的越级分离是否是影响被标记为“超侵入性”基因极快传播到本地种群的一个主要因素。研究人员将测量和比较原生、引进和杂交虎鳗在多个生命阶段的代谢率、失水率、对同种密度的压力反应和热耐力，这些类别对于预测在真实加州的传播很重要。关于土著和杂交火蜥蜴的数据将使用圈养的原生和杂交个体火蜥蜴群体来生成。亲代的非本土火蜥蜴将从它们本土范围内的几个野生种群以及目前在与本土物种重叠的区域之外的引进种群中收集。学习到的信息将与一种新的群体遗传模拟一起使用，以生成对真实加州景观中本地和非本地基因在当前和潜在未来条件下的扩散和持久性的强有力的机械预测。

Major rapid evolutionary changes are well known, but the underlying mechanisms and how these changes influence survival and reproduction are often unclear. This project will address the process of rapid evolutionary change by investigating whether the success and geographic spread of an introduced salamander species is the result of interbreeding with a native species. Although the introduction of non-native species is thought to lead to rapid evolution, it is still not understood how often this occurs, the factors involved, and whether this promotes the success and spread of the introduced species. Sometimes introduced species hybridize with native species and produce viable offspring that exhibit extreme trait values not present in either parental species. For example, offspring may be bigger than either parental species or have an increased tolerance to environmental stressors. Potentially, such hybrid offspring can outcompete the parental species or colonize new environments not occupied by either parental species. The production of extreme trait values due to interbreeding - transgressive segregation - is rare in viable offspring. However, when it occurs the offspring can interact with the environment in entirely new ways, leading to rapid evolutionary change. The researchers will study genetic mixing between an endangered native species, the California tiger salamander, and a closely related introduced species, the barred salamander, to test the hypothesis that transgressive segregation has led to extremely rapid evolution in the native species. Data will reveal how life history, physiology, and habitat combine to determine genetic pattern across a region where the two species overlap and hybridize. The project also includes the training of undergraduate and graduate students, educational programs targeting K-12 students, and workshops for conservation managers. Hybrids between Ambystoma tigrinum mavortium and A. californiense exhibit transgressive segregation with respect to body size and exhibit a broader thermal tolerance than natives. However, we still do not know whether transgressive segregation of ecologically important traits is a major factor affecting the extremely rapid spread of what are being labeled "superinvasive" genes into native populations. The researchers will measure and compare metabolic rates, rates of water loss, stress response to conspecific density, and thermal tolerance at multiple life stages in native, introduced, and hybrid tiger salamanders, the categories that matter for predicting spread on the real California landscape. Data on native and hybrid salamanders will be generated using a captive colony of salamanders of native and hybrid individuals. Parental, non-native salamanders will be collected from several wild populations within their native range and from an introduced population that is currently outside the zone of overlap with the native species. Information learned will then be used along with a novel population genetic simulation to generate robust mechanistic predictions of dispersal and persistence of native and nonnative genotypes within the real California landscape under current and potential future conditions.