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Genetic Characterization of Invasion and Hybridization: A Bittersweet (Celastrus spp.) Story.

机译：入侵和杂交的遗传特征：苦乐参（Celastrus spp。）的故事。

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One objective of my dissertation research was to determine if the decline of a North American vine (American bittersweet, Celastrus scandens ) in the eastern portion of its range is related to reproductive interference (including hybridization) from an introduced congener (oriental bittersweet, C. orbiculatus). Chapters 1 and 2 address this question.;In the first study I used genetic markers and field observation to survey individuals across the USA to determine the prevalence of hybrids, and whether hybrid swarms are the driving force behind the invasion by C. orbiculatus . I found that hybrids are widespread, but only eight percent of non-native genotypes surveyed were hybrids. Although established hybrids were uncommon, other evidence in our study suggested that gene flow and reproductive interference may be important factors in the decline of C. scandens . Unidirectional pollen flow was evident from genetic analysis of a maternally inherited marker, where all 20 hybrids tested in this study showed the cpDNA signature of C. scandens. When asymmetry in pollen flow favors male fecundity in an introduced species, declines in a native species are greatly accelerated.;In Chapter 2 I investigated the reproductive interaction between the two bittersweet species in more detail at a field site where they both occur and reproduce. I evaluated the effect of proximity and floral output of conspecific and interspecific males on fertilization and hybridization rates in the two species. I did not find evidence that C. orbiculatus prevents fertilization of C. scandens ovules, but genetic tests of seedlings provide strong evidence for reproductive interference. Fifty-one percent of C. scandens seeds were hybrids, compared to 1.6% of C. orbiculatus seeds. If hybrid seedlings are not considered as contributors to fitness, it is plausible that the decline in the native vine in the presence of the introduced species can be tied to the reproductive effort or opportunity wasted on hybrids. Hybridization rate in C. scandens was negatively associated with distance to the nearest interspecific individual, demonstrating that efforts to conserve that native must reduce exposure to C. orbiculatus. The degree of isolation required is greater than conventional cases where only competition is considered, as reproductive interference in this system can be substantial at distances as great as 100m.;In Chapter 3, I used genetic markers to test the species identity of commercially available plants marketed as "American bittersweet" or "Celastrus scandens" and found that the majority of samples and named varieties obtained were actually C. orbiculatus . The substitution may occur intentionally because C. orbiculatus is easier to grow and has a long history in horticulture, or unintentionally because growers may confuse the species. Mislabeled C. orbiculatus was significantly less expensive than C. scandens, giving even well-meaning consumers the incentive to propagate and spread the introduced species. Human commerce is amongst the most important dispersal agents of introduced species, and understanding its role in the continuing spread of C. orbiculatus is essential in any large scale attempt to control the spread of the introduced vine and its negative effect on natural communities, and C. scandens in particular.;In Chapter 4, I used experimental trials in a greenhouse setting to simulate the elevated atmospheric carbon dioxide and increased nitrogen deposition expected in the future. I tested hypotheses regarding differential responses of C. orbiculatus and C. scandens to the increased availability of carbon dioxide and nitrogen, and the interactive effects of elevated carbon dioxide and nitrogen. The total biomass of neither species responded to either treatment. Biomass allocation in C. scandens significantly responded to carbon dioxide and competition treatments, while biomass allocation in C. orbiculatus responded to nitrogen, carbon dioxide, and competition treatments. The results suggest increased phenotypic plasticity in C. orbiculatus, a factor that is often associated with successful invaders, and that C. orbiculatus may be better able to cope with future changes to biogeochemical cycles. (Abstract shortened by UMI.).
机译：我的论文研究的一个目标是确定北美葡萄藤（美洲苦甜，Celastrus scandens）在其范围东部的衰退是否与引入的同类动物（东方苦甜，C）的繁殖干扰（包括杂交）有关。 orbiculatus）。第1章和第2章解决了这个问题。在第一个研究中，我使用遗传标记和现场观察来调查美国各地的个体，以确定杂种的流行程度，以及杂种群是否是由白色念珠菌入侵的驱动力。我发现杂种很普遍，但是在调查的非本地基因型中只有8％是杂种。尽管成熟的杂种很少见，但我们研究中的其他证据表明，基因流和生殖干扰可能是导致scan虫下降的重要因素。从母系遗传标记的遗传分析中可以明显看出单向花粉流动，在这项研究中测试的所有20个杂种均显示了C. scandens的cpDNA签名。当花粉流动的不对称性有利于引入物种的雄性繁殖力时，原生物种的衰落将大大加速。在第二章中，我在这两个苦甜物种发生和繁殖的田间地点更详细地研究了它们之间的生殖相互作用。我评估了同种和种间雄性的亲缘关系和花输出对这两个物种的受精率和杂交率的影响。我没有找到证据证明白色念珠菌阻止scan树胚珠的受精，但是对幼苗的基因测试为生殖干扰提供了有力的证据。 51％的C. scandens种子是杂种，而1.6％的C. orbiculatus种子是杂种。如果杂种幼苗不被认为是促进健康的因素，则可以认为，在引入种的情况下，天然藤本植物的衰弱可能与杂种的繁殖努力或机会浪费有关。 scan虫的杂交率与到最近的种间个体的距离呈负相关，这表明保护本地人的努力必须减少对白色念珠菌的暴露。与仅考虑竞争的常规情况相比，所需的隔离度更高，因为该系统中的生殖干扰在100m的距离内可能是相当大的。；在第3章中，我使用遗传标记测试了市售植物的物种身份以“ American bittersweet”或“ Celastrus scandens”的形式销售，发现获得的大多数样品和命名品种实际上是C. orbiculatus。这种替代可能是有意发生的，因为小or衣梭菌更容易生长并且在园艺中历史​​悠久，或者无意是因为种植者可能使该物种混淆。贴错标签的白色念珠菌的价格要比白色念珠菌便宜得多，即使是善意的消费者也有动机繁殖和传播引入的物种。人类贸易是引进物种最重要的传播媒介之一，因此，在任何大规模控制引进葡萄蔓延及其对自然群落的负面影响的尝试中，了解其在梭菌持续传播中的作用至关重要。在第4章中，我在温室环境中进行了实验性试验，模拟了预期中将来大气中二氧化碳含量升高和氮沉积增加的现象。我测试了关于假山梭菌和scan孢梭菌对二氧化碳和氮的增加利用率以及二氧化碳和氮升高的相互作用的不同反应的假设。两种物种的总生物量均对两种处理均无反应。 scan树的生物量分配对二氧化碳和竞争处理有显着的响应，而小球藻的生物量分配对氮，二氧化碳和竞争处理有响应。结果表明，白色念珠菌的表型可塑性增加，这通常与成功入侵者有关，而白色念珠菌可能能够更好地应对生物地球化学循环的未来变化。 （摘要由UMI缩短。）。

著录项

  • 作者

    Zaya, David N.;

  • 作者单位

    University of Illinois at Chicago.;

  • 授予单位 University of Illinois at Chicago.;
  • 学科 Ecology.;Botany.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 103 p.
  • 总页数 103
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 遥感技术;
  • 关键词

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