• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Genetic variation and population structure in the endangered houston toad in contrast to its common sympatric relative, the coastal plain toad.
【24h】

Genetic variation and population structure in the endangered houston toad in contrast to its common sympatric relative, the coastal plain toad.

机译：濒临灭绝的休斯顿蟾蜍的遗传变异和种群结构与其常见的同胞亲属沿海平原蟾蜍相反。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

This is the first study to assess genetic variation in the endangered Houston toad, Bufo houstonensis (Anura: Bufonidae). Samples from across its range were used to determine the number of populations and the levels of diversity within and among populations. D-loop (mtDNA) sequences from 160 individuals were analyzed, and variation at ten microsatellite loci was examined for 439 individuals. Genetic clustering analyses indicate nine populations across the range; five of these populations occurred in Bastrop County. The most divergent population was in Austin County. Gene flow was generally low, but was higher at distances <4 km. Overall, genetic diversity was high across the range and within populations. Recent surveys indicate population sizes are low and are decreasing; accordingly, annual monitoring of all known populations and increasing the number of toads (e.g., through headstarting programs) are proposed for immediate implementation. More general, but crucial, recommendations include preservation of all three habitat types (breeding/nursery, occupied, and dispersal), special attention towards the Austin County population, and involvement of the general public in conservation.;The coastal plain toad, Bufo nebulifer, is sympatric with B. houstonensis through all of the latter species' range. Examination of more common sympatric congeners may be necessary to effectively manage rare or endangered species, especially in cases where widespread or frequent hybridization is known or when human activities increases the rates of hybridization. Bufo houstonensis and B. nebulifer are known to hybridize, and while recent work has been done to investigate the genetic diversity and structure within B. houstonensis, no comparable data yet exist for B. nebulifer. I investigated population genetic structure and diversity, including migration/movement rates, at both the landscape and fine scales. Much of the range was sampled and nine groups were recovered. Their relationships may be explained by a long residence in much of its present-day distribution (at least tens of thousands of years), with a history of range contraction during glaciation and re-expansion following the retreat of glaciers. Bufo houstonensis and B. nebulifer have comparable levels of genetic diversity, but B. nebulifer seems to migrate less frequently or less distance than its endangered congener.;In order to effectively protect endangered species, natural levels of interspecific hybridization, or admixture, must be characterized, especially in cases where anthropogenic changes to the environment may broaden contact between the species. I investigated the baseline levels of admixture in B. houstonensis using mitochondrial sequence data and microsatellite loci. Admixture between B. houstonensis and two sympatric species (B. nebulifer and B. woodhousii) was detected. Phenotype-based assessments of admixture appear to be temporally stable, but they underestimate true levels of admixture. Bufo nebulifer x B. houstonensis F1 hybrids can be fertile and backcross to B. nebulifer; B. nebulifer x B. houstonensis matings may result in fertile offspring more frequently than previously thought. Admixed individuals with B. houstonensis or B. woodhousii maternal lineages can backcross to B. houstonensis. Phenotypically aberrant individuals were not always F1 hybrids, and F1 hybrids were not always phenotypically aberrant. With continued habitat alteration and rising temperatures, both habitat isolation and offset breeding season have already partially broken down and may deteriorate further, consequently, opportunities for hybridization events will increase. Selection against hybrids at the tadpole stage did not occur among B. houstonensis and B. nebulifer individuals. All these factors may also lead to higher levels of gamete wastage in B. houstonensis, an already critically endangered species.;Thirty-five published microsatellite loci were screened in several Bufo species, chiefly B. houstonensis and its two common, sympatric relatives, B. nebulifer and B. woodhousii. Twelve loci were polymorphic in the three focal species. For some loci, amplification was observed in distantly related species. Natural hybridization occurs within the genus Bufo and laboratory crosses often result in viable or fertile offspring. These microsatellite loci may be used to address questions of interspecific admixture as well as baseline intraspecific genetic variation.
机译：这是第一项评估濒临灭绝的休斯顿蟾蜍Bufo houstonensis（Anura：Bufonidae）的遗传变异的研究。使用其范围内的样本来确定种群数量以及种群内部和种群之间的多样性水平。分析了来自160个个体的D环（mtDNA）序列，并检查了439个个体在十个微卫星基因座处的变异。遗传聚类分析表明该范围内有9个种群；其中五个人口发生在巴斯特罗普县。人口分歧最大的是奥斯丁县。基因流量通常较低，但在距离小于4 km时较高。总体而言，整个范围内和种群内遗传多样性很高。最近的调查表明，人口数量很少且正在减少。因此，建议立即对所有已知种群进行年度监测并增加蟾蜍的数量（例如，通过启动计划）。更一般但重要的建议包括保护所有三种栖息地类型（繁殖/哺育，居住和散布），对奥斯丁县人口的特别关注以及公众对保护的参与。沿海平原蟾蜍，蟾蜍星云。在整个后一物种的整个范围内，它与休斯敦芽孢杆菌同属。为了有效地管理稀有或濒临灭绝的物种，可能有必要对更常见的同胞祖先进行检查，特别是在已知广泛或频繁杂交的情况下，或者当人类活动增加了杂交速度时。已知Bufo houstonensis和B. nebulifer可以杂交，尽管最近进行了研究以研究B. houstonensis的遗传多样性和结构，但尚无可用于B. nebulifer的可比数据。我研究了景观和精细尺度上的种群遗传结构和多样性，包括迁徙/移动率。对范围的大部分进行了采样，并回收了九组。它们之间的关系可以用它在当今大部分时间中的长期居住（至少数万年）来解释，在冰川退缩后冰川作用和重新扩张过程中有范围收缩的历史。 Bufo houstonensis和B. nebulifer的遗传多样性水平相当，但是B. nebulifer的迁移频率或频率远低于其濒危同类动物。为了有效保护濒危物种，必须在自然水平上进行种间杂交或混合特别是在人为环境变化可能扩大物种之间接触的情况下。我使用线粒体序列数据和微卫星基因座研究了休斯敦德酵母中掺混物的基线水平。发现了休斯敦芽孢杆菌和两个同胞物种（B. nebulifer和B. woodhousii）之间的混合物。基于表型的混合物评估在时间上是稳定的，但它们低估了混合物的真实水平。 Bufo nebulifer x B. houstonensis F1杂种可以繁殖并与B. nebulifer回交。 B. nebulifer x B. houstonensis交配可能比以前认为的更频繁地产生可育后代。与休斯敦芽孢杆菌或伍德霍斯芽孢杆菌母系的混合个体可以回交至休斯敦芽孢杆菌。表型异常的人并不总是F1杂种，F1杂种也不总是表型异常。随着生境的不断变化和温度的升高，生境隔离和繁殖季节的偏移已经部分破坏，并可能进一步恶化，因此，杂交事件的机会将增加。在休斯顿B. houstonensis和B. nebulifer个体之间未进行针对at期杂种的选择。所有这些因素也可能导致已经极度濒危的B. houstonensis的配子浪费水平更高;;在几个Bufo物种中筛选了35个已发表的微卫星基因座，主要是B. houstonensis及其两个同胞同伴。 nebulifer和B. woodhousii。在三个焦点物种中有十二个位点是多态的。对于某些基因座，在远缘物种中观察到扩增。天然杂交发生在Bufo属内，实验室杂交通常会导致存活或繁殖的后代。这些微卫星基因座可用于解决种间混合以及基线种内遗传变异的问题。

著录项

  • 作者

    McHenry, Diana J.;

  • 作者单位

    University of Missouri - Columbia.;

  • 授予单位 University of Missouri - Columbia.;
  • 学科 Ecology.;Conservation biology.;Genetics.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 297 p.
  • 总页数 297
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号