DISSERTATION RESEARCH: Quantifying the tempo of genome theft in polyploid, female-only Ambystoma salamanders

这个项目将测试一个假设，以解释一个只有雌性的蝾螈谱系如何能够持续数百万年。大多数动物都是有性繁殖的，尽管繁殖雄性的进化代价很高。雄性与雌性争夺资源，降低了雌性与后代之间的基因相似性。很少有动物不交配而繁殖，大多数动物只生存很短的进化时间。然而，蝾螈的全雌性谱系（北美已知最古老的全雌性脊椎动物）已经能够持续大约600万年。由于无性动物的持久性是罕见的，它们可以为有性繁殖的成本和收益提供有价值的线索。有时，这些雌性蝾螈能够从近亲的雄性蝾螈那里获得新的遗传物质。因此，它们可以获得有性繁殖和无性繁殖的好处。为了验证这一观点，研究人员将在进化过程中测量从有性物种到全雌性无性物种的遗传贡献的重要性。此外，该项目还将包括对本科生和研究生的培训，以及博物馆展览和社交博客等外展活动。这项研究将量化速度性物种的基因组进化历史渗漏和单性钝口螈属血统,这将允许我们测试假设复发基因组的贡献占单性钝口螈属大血统年龄比其他gynogenetic类群。研究人员将使用基因组规模的数据和进化人口模型来评估多种进化情景，从有性物种没有遗传贡献，到最近（但有限）的基因组贡献，或正在进行的基因组贡献。这将通过使用定制的生物信息学工具来分类单性蝾螈的多个基因组中的遗传变异，将这种变异与被认为是单性蝾螈新遗传变异来源的有性物种的基因组进行比较，然后使用统计遗传模型来估计单性蝾螈和有性蝾螈之间遗传交换的幅度和时间。

This project will test a hypothesis to explain how a lineage of female-only salamanders has been able to persist for millions of years. Most animals reproduce sexually even though there is a high evolutionary cost of making males. Males compete with females for resources and decrease the genetic resemblance between a female and her offspring. Few animal species reproduce without mating and most only live for a short evolutionary time. However, an all-female lineage of salamanders (the oldest known all-female vertebrate in North American) has been able to persist for approximately 6 million years. Because the persistence of asexual animals is rare, they can provide valuable clues about the costs and benefits of sexual reproduction. Sometimes these female-only salamanders are able to obtain new genetic material from males of closely related species. Thus, they may gain the benefits of both sexual and asexual reproduction. To test this idea, the researchers will measure the importance of genetic contributions from sexual species into the all-female asexual species over evolutionary time. In addition, the project will include the training of undergraduate and graduate students and outreach activities such as museum displays and social blogs. This research will quantify the rate and evolutionary history of genome leakage from sexual species in to the unisexual Ambystoma lineage, which will allow us to test the hypothesis that recurrent genome contribution accounts for the greater lineage age of unisexual Ambystoma as compared to other gynogenetic taxa. The researchers will use genome-scale data and evolutionary demographic modeling to evaluate multiple evolutionary scenarios ranging from no genetic contributions from sexual species, to recent (but limited) genome contributions only, or ongoing genome contributions. This will be accomplished by using custom bioinformatics tools to sort genetic variation among the multiple genomes of unisexual salamanders, comparing this variation to that of the genomes of sexual species thought to be the source of novel genetic variation in unisexuals and then using statistical genetic models to estimate the magnitude and timing of genetic exchange between unisexual and sexual salamanders.