Evolution of species interactions in adaptive radiation

适应性辐射中物种相互作用的演变

• 批准号: RGPIN-2021-03177
• 负责人: Schluter, Dolph
• 金额: $ 6.92万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742419
• 关键词: Evolution; species; interactions; adaptive; radiation

My research program investigates the causes of adaptive radiation, defined as the evolution of ecological diversity in a rapidly diversifying lineage. I propose to carry out experiments to test mechanisms of selection on genes and genomes. My main study organism is threespine stickleback fish, a supermodel organism having many experimental advantages and exhibiting rampant parallel evolution, aiding comparative phenotypic and genomic studies. I describe three major projects. 1) Character displacement and reproductive isolation. Evolution of competitive interactions is a hallmark of adaptive radiation. However, there are as yet no experimental tests of whether resource competition drives evolution in a natural system. The contribution of competition to evolution of reproductive isolation (speciation) is even less well understood. Conflicting theories of adaptive radiation differ by whether character displacement is an integral part of speciation or occurs later. We will use a pond evolution experiment with stickleback to test whether competition leads to divergent evolution in the same regions of the genome already known to underlie niche divergence and assortative mating.  2) The evolution of hybrid genomes. Postzygotic reproductive isolation is hypothesized to evolve more slowly than premating isolation and to play a reduced role early in speciation.  We propose three investigations of the role of gene-gene incompatibilities in hybrids of young stickleback species. First, we will use a pond experiment to test the prediction that gene-gene incompatibilities in F2 hybrids should favor increased heterozygosity genome-wide. Second, we will measure the direction of evolution of minor-parent alleles in wild hybrid populations. Third, we will conduct a multigenerational experimental test of the prediction that that gene-gene incompatibilities should favor major-parent alleles in experimental backcross populations introduced to ponds. Gene-gene interactions are predicted to select against minor parent alleles because they experience more potential antagonistic interactions with major parent alleles regardless of which species is the minor parent. In contrast, ecological adaptation should result in parallel evolution of allele frequencies between populations regardless of major and minor parent allele frequencies. 3) Maintenance of standing genetic variation. The leading hypothesis for the maintenance of standing genetic variation in colonizing populations is that allele frequency is a balance between migration and selection. We will test two unique predictions of this hypothesis for maintaining freshwater alleles in marine threespine stickleback. We will use a bank of 1000 stickleback genome sequences to test if freshwater allele copies in marine individuals have a nearby freshwater source. Second, we will test whether freshwater allele copies found in the sea show a genomic signature of having arrived in the sea only relatively recently.

我的研究项目调查适应性辐射的原因，定义为在一个快速多样化的谱系中生态多样性的进化。我建议开展实验来测试基因和基因组的选择机制。我的主要研究对象是三刺鱼，这是一种超模生物，具有许多实验优势，并表现出猖獗的平行进化，有助于比较表型和基因组研究。我描述了三个主要项目。1)性格位移和生殖隔离。竞争相互作用的进化是适应性辐射的一个标志。然而，目前还没有关于资源竞争是否推动自然系统进化的实验测试。竞争对生殖隔离（物种形成）进化的贡献甚至不太清楚。相互矛盾的适应性辐射理论的不同之处在于，特征位移是物种形成的组成部分还是后来发生的。我们将对棘鱼进行池塘进化实验，以测试竞争是否会导致基因组相同区域的分化进化，这些区域已经被认为是生态位分化和分类交配的基础。2)杂交基因组的进化。假设合子后生殖隔离比早熟隔离进化得更慢，并且在物种形成早期发挥的作用较小。我们提出了三个研究的作用，基因-基因不相容在幼棘鱼种杂交。首先，我们将使用一个池塘实验来验证F2杂交种的基因-基因不亲和性应该有利于增加全基因组杂合性的预测。其次，我们将测量野生杂交群体中少数亲本等位基因的进化方向。第三，我们将对引入池塘的回交群体的基因-基因不相容倾向于主亲本等位基因的预测进行多代实验检验。基因-基因相互作用被预测为对次要亲本等位基因的选择，因为无论哪个物种是次要亲本，它们与主要亲本等位基因的潜在拮抗相互作用更多。相反，生态适应应导致种群间等位基因频率的平行进化，而不管亲本的主要等位基因频率和次要等位基因频率。3)常备遗传变异的维持。在殖民群体中维持常备遗传变异的主要假设是，等位基因频率是迁移和选择之间的一种平衡。我们将测试这一假设的两个独特的预测维持淡水等位基因在海洋三刺棘鱼。我们将使用1000个棘鱼基因组序列库来测试海洋个体的淡水等位基因拷贝是否有附近的淡水来源。其次，我们将测试在海洋中发现的淡水等位基因拷贝是否显示出最近才到达海洋的基因组特征。