Evolution of species interactions in adaptive radiation

我的研究项目调查适应性辐射的原因，定义为生态多样性在迅速多样化的谱系中的进化。我建议进行实验来测试基因和基因组的选择机制。我的主要研究生物是三棘鱼，这是一种具有许多实验优势的超级模式生物，并表现出猖獗的平行进化，有助于比较表型和基因组研究。我介绍了三个主要项目。 1)性格置换和生殖隔离。竞争性相互作用的进化是适应性辐射的标志。然而，目前还没有实验测试资源竞争是否会推动自然系统的进化。竞争对生殖隔离（物种形成）进化的贡献甚至更不清楚。适应性辐射理论的分歧在于，性格置换是物种形成的一个组成部分，还是发生在物种形成之后。我们将使用一个池塘进化实验棘鱼测试是否竞争导致分化的进化在相同的区域的基因组已经知道的生态位分化和选择性交配的基础。 2)杂交基因组的进化。合子后的生殖隔离被假设为比交配前的隔离进化得更慢，并在物种形成的早期发挥减少的作用。 我们提出了三个调查的作用，基因的基因不相容性在年轻的刺鱼物种的杂交。首先，我们将使用池塘实验来测试的预测，在F2杂种的基因-基因不亲和性应该有利于增加全基因组的杂合性。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，我们将进行一个多代的实验测试的预测，基因-基因不相容性应有利于主要的父母等位基因在实验回交群体引入池塘。基因-基因相互作用被预测为选择对抗次要亲本等位基因，因为它们与主要亲本等位基因经历更多潜在的拮抗相互作用，而不管哪个物种是次要亲本。相反，生态适应应导致种群之间等位基因频率的平行进化，而不管主要和次要亲本等位基因频率。 3)保持现有的遗传变异。在殖民群体中维持长期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平衡。我们将测试这一假设的两个独特的预测保持淡水等位基因在海洋threespine刺鱼。我们将使用1000个棘鱼基因组序列的数据库来测试海洋个体中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副本是否显示出最近才到达海洋的基因组特征。

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.