权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

DISSERTATION RESEARCH: Reinforcement of isolation between parasite host races

论文研究：加强寄生虫宿主种族之间的隔离

基本信息

批准号：
1601370
负责人：
Judith Bronstein
金额：
$ 2万
依托单位：
University of Arizona
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2018-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1601370&HistoricalAwards=false
关键词：
DISSERTATION RESEARCH Reinforcement isolation between

项目摘要

A long-standing debate in evolutionary biology is how reproductive barriers among species can arise in the absence of geographic obstacles. New parasite species can often form following infection of a novel host species if barriers to successful reproduction between parasites on the two species exist. This project combines observational, experimental, and genomic studies of a native parasitic plant, desert mistletoe, to address this question. While showing the same epidemiological patterns as many other parasites, parasitic plants allow for direct tests of hypotheses concerning the evolution of barriers to mating in diverging parasite lineages that would be infeasible in other systems. This research will help elucidate the poorly understood ecological mechanisms that promote parasite speciation and adaptation to novel hosts. The potential for studying parallel evolution of parasites undergoing ongoing diversification provides a unique opportunity to study the genomics of species interactions. Additionally, the researchers will disseminate the results to a broad audience through collaborations with local outreach groups interested in native plants and will contribute to the training of graduate and undergraduate students.This work will test established theory about the relative roles of pre-zygotic and post-zygotic isolation mechanisms in sympatry and allopatry using two host races of a native aerial hemiparasite of plants, Phoradendron californicum (Viscaceae), across their overlapping ranges. Populations of the host races infecting catclaw acacia (Senegalia greggii ) and velvet mesquite (Prosopis velutina) in sympatry (locally interspersed) and allopatry ( 3 km from nearest infected host of other species) will be studied at multiple sites across Arizona. The researchers will conduct selection gradient analyses for flowering time across these populations to test if selection for divergent flowering times (a pre-zygotic isolation mechanism) between the host races is stronger in sympatry than in allopatry. Additionally, the researchers will perform hand-pollination experiments to quantify the cost of mating between host races and the strength of late-acting barriers to gene flow. Finally, population genomic analyses of mistletoes from these host races using RAD sequencing will reveal whether host races are the result of a single host-switching event or repeated, parallel divergence and reinforcement across the range. The researchers will further use the sequence data to investigate the genomic signature of host race formation and adaptation to host species in this parasitic plant.

进化生物学中一个长期存在的争论是，在没有地理障碍的情况下，物种之间的生殖障碍是如何产生的。如果两种寄生虫之间存在成功繁殖的障碍，新的寄生虫物种通常可以在感染新的宿主物种后形成。该项目结合了对本地寄生植物沙漠槲寄生的观察、实验和基因组研究来解决这个问题。虽然显示出相同的流行病学模式，许多其他寄生虫，寄生植物允许直接测试的假设有关的演变障碍，交配在不同的寄生虫谱系，这将是不可行的，在其他系统。这项研究将有助于阐明鲜为人知的生态机制，促进寄生虫物种形成和适应新的主机。研究寄生虫的平行进化正在进行多样化的潜力提供了一个独特的机会，研究物种相互作用的基因组学。此外，研究人员将通过与当地对本土植物感兴趣的外展团体合作，向广大受众传播研究结果，并将为研究生和本科生的培训做出贡献。这项工作将使用植物的本地空气半寄生物的两个宿主种族，Phoradendron californicum（Viscaceae），在它们的重叠分布区。将在亚利桑那州的多个地点研究同域分布（局部散布）和异地分布（距离最近的其他物种感染宿主3公里）中感染猫爪金合欢（Senegalia gregalus）和天鹅绒牧豆树（Prosopis velutina）的宿主种族种群。研究人员将对这些种群的开花时间进行选择梯度分析，以测试宿主种族之间对不同开花时间的选择（前合子隔离机制）是否在同域性中比在异地性中更强。此外，研究人员将进行人工授粉实验，以量化宿主种族之间的交配成本和基因流动的后期作用障碍的强度。最后，使用RAD测序对这些宿主种族的槲寄生进行群体基因组分析，将揭示宿主种族是否是单一宿主转换事件的结果，或者是整个范围内重复的平行发散和强化。研究人员将进一步使用序列数据来研究这种寄生植物中宿主种族形成和适应宿主物种的基因组特征。