Alien gene introgression promotes rapid adaptation: an unconscious experiment on Fire-bellied toad (Bombina bombina) at the northern edge of its distribution range

外来基因渗入促进快速适应：对火腹蟾蜍（Bombinaombina）分布范围北缘的无意识实验

基本信息

批准号：
274681367
负责人：
Professor Dr. Ralph Tiedemann, Ph.D.
金额：
--
依托单位：
Institut für Biochemie und Biologie
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/274681367?language=en
关键词：
Alien gene introgression promotes rapid

项目摘要

This proposal focusses on genomic sources of adaptive variation for rapid change (thematic group 3), by evaluating particular hypotheses, i.e., (1) small isolated populations at the margin of a species distribution might be constrained by a lack of standing genetic variation and (2) introgression of allochthonous alleles may enhance the adaptive potential of such populations. In case of introgression, heterozygosity and allelic diversity increase instantly and sexual reproduction creates mosaic genotypes combining different sets of authochthonous and allochthonous alleles, providing the raw material for rapid adaptation. Our study organism is the Fire-bellied toad Bombina bombina, which occurs in Europe in two distinct evolutionary lineages, i.e., a southern lineage distributed in the Balkan states and Austria, and a northern lineage reaching from Ukraine through Poland to the edges of the northern distribution range in Northern Germany and Southern Sweden. Initial genetic analyses at 20 unlinked genetic loci unraveled an introgression of southern lineage (putatively Austrian) genotypes into three local northern lineage populations, presumably due to independent unofficial (and illegal) release by amateur herpetologists. Interestingly, these introgressed populations (1) are fixed for introgressed alleles at several loci and (2) have a positive population trend, such that they outperform local authochthonous populations. This scenario provides a replicated unconscious experiment, mimicking long-distance dispersal and subsequent introgression from a southern lineage (potentially adapted to warmer summer conditions) to a northern population. We will perform genomic scans (RAD-seq) and expression profiling (RNA-seq) for both the authochthonous and the introgressed Bombina populations to discern, on a genomic scale, introgressed alleles/expression patterns from authochthonous ones. In genome-wide association studies (GWAS), we will relate these patterns to fitness related traits (body size, mass, condition). These data will be fed into theoretical models developed by our collaborator (Prof. Stephan) to discern the relative importance of selective sweeps vs. polygenic selection in rapid adaptation. In-depth analysis of candidate genes (including MHC and heat shock protein genes) will unravel the functional classes, in which introgressed (allochthonous) alleles will be favored by selection, and in which ones authochthonous alleles are maintained. This will provide us with a causal understanding of the reason, why introgressed populations of the Fire-bellied toad at the northern edge of the distribution range outperform the non-introgressed ones. Ultimately, the project focusses on the relevance of introgression as a mechanism to increase the amount of standing genetic variation and thus to contribute adaptive genetic material for rapid adaptation.

该建议的重点是通过评估特定的假设，即，（1）物种分布边缘处的小隔离群体的少量孤立种群可能会受到缺乏遗传遗传变异的限制，并且（2）同种异性侵入这种适应性的群体可能会增强这种适应性的潜力。在渗入的情况下，杂合性和等位基因多样性立即增加，有性繁殖创造了镶嵌基因型，结合了不同的认证和同种等位基因，为快速适应提供了原材料。我们的研究生物是造成火孔的蟾蜍bombina bombina，在欧洲发生在两个不同的进化谱系中，即在巴尔干各州和奥地利分布的南部谱系，以及一个从乌克兰到达波兰的北部血统，到达北德国和北部瑞典北部分布范围的边缘。最初的遗传分析在20个未链接的遗传基因座上揭示了南部谱系（原始的奥地利）基因型渗入三个局部北部谱系种群中，这大概是由于业余疱疹学家独立的非官方（和非法）释放。有趣的是，这些侵入性的人群（1）是在几个基因座的渗透等位基因固定的，并且（2）具有积极的人口趋势，因此它们的表现要优于局部认证人群。这种情况提供了一个复制的无意识的实验，模仿了长距离传播，并随后从南部谱系（可能适应较温暖的夏季状况）到北部人口的渗透。我们将对认证和侵入性的bombina种群进行基因组扫描（RAD-SEQ）和表达分析（RNA-SEQ），以辨认出基因组规模，从正面的等位基因范围辨认出渗透的等位基因/表达模式。在全基因组关联研究（GWAS）中，我们将将这些模式与适应性相关的特征（体型，质量，状况）联系起来。这些数据将被馈入我们的合作者（Stephan教授）开发的理论模型，以辨别在快速适应中选择性扫描与多基因选择的相对重要性。对候选基因（包括MHC和热休克蛋白基因）的深入分析将揭示功能类别，其中选择性（同种）等位基因将受到选择的偏爱，并且在其中维持验证等位基因。这将为我们提供对原因的因果理解，为什么在分配范围的北部边缘的火腹蟾蜍的渗透率胜过了未造成的蟾蜍。最终，该项目的重点是渗入的相关性作为增加遗传变异量的机制，从而有助于自适应遗传物质以进行快速适应。