The Genetics of Parallel Reproductive Isolation in Stickleback Species Pairs

描述（由申请人提供）：在过去十年中，在理解自然选择如何推动物种起源方面取得了实质性进展。然而，我们对物种形成的遗传基础知之甚少——这些基因决定了行为、形态和其他特征，这些特征决定了新物种之间的繁殖障碍。由于缺乏既能理解生态和进化背景又能提供必要的基因组资源的研究系统，研究进展受到限制。三刺棘鱼（Gasterosteus aculeatus complex）的幼种对为解决有关物种起源和自然界持久性的遗传学基本问题提供了一个绝佳的机会。共存的“沼泽”和“底栖”物种在多个小湖泊中反复进化，并在许多特征上表现出相似的差异。交配行为，如筑巢栖息地和配偶偏好，构成了基因流动的主要障碍。这种行为还取决于体型、形状和栖息地等生态差异，因此间接影响生殖隔离。杂交种的生存和繁殖成功同样依赖于这一套行为和形态特征。本研究的第一个目的是利用高密度单核苷酸多态性（SNP）阵列的数量性状位点（QTL）定位，研究来自两个湖泊（Priest和Paxton）的底栖和沼泽刺鱼之间生殖隔离的行为和形态特征的遗传基础。其次，我们的目标是确定导致生殖隔离的行为特征是否与已知与配偶选择相关的形态特征位于相同的基因组区域。我们的第三个目标是通过测量这些池塘饲养的杂交种与实验室制造的对照胚胎中SNP标记的分离扭曲，来检测导致合子后分离的基因组区域。最后，我们将测试相同的基因组区域是否控制着两个独立进化的物种对（在Priest和Paxton Lakes）之间的行为和形态差异。重要的是，这些特征将在模拟自然湖泊栖息地的受控室外实验池塘中进行测量，并允许自然行为，饮食，生长和繁殖时间表的表达。由于棘鱼有完整的基因组测序和许多其他可用的遗传工具，因此这里提出的定位实验将是确定自然棘鱼种群中生殖隔离的基因的第一步。此外，这些结果可能对理解人类行为变异和行为障碍的遗传基础具有重要意义，因为许多行为背后的遗传和神经通路在鱼类和人类之间可能是保守的。

DESCRIPTION (provided by applicant): Substantial progress has been made over the last ten years in understanding how natural selection has driven the origin of species. However, we know little about the genetic basis of speciation - the genes that underlie the behavioral, morphological, and other traits that define the reproductive barriers between new species. Progress has been limited by a shortage of study systems that present both an understanding of ecological and evolutionary context and the requisite genomic resources. The young species pairs of threespine stickleback fish (Gasterosteus aculeatus complex) provide an outstanding opportunity to address fundamental questions concerning the genetics of species origin and persistence in nature. Coexisting 'limnetic' and 'benthic' species have evolved repeatedly in multiple small lakes and show parallel differences in many traits. Mating behaviors such as nesting habitat and mate preferences form the principal barrier to gene flow. Such behaviors are also contingent upon body size, shape, and ecological differences such as habitat, which therefore indirectly influence reproductive isolation. Survival and reproductive success of hybrids likewise depend on this suite of behavioral and morphological traits. The first aim of our proposed research is to investigate the genetic underpinnings of behaviors and morphological traits responsible for reproductive isolation between benthic and limnetic sticklebacks from two lakes (Priest and Paxton) using quantitative trait locus (QTL) mapping with high-density single nucleotide polymorphism (SNP) arrays. Second, we aim to determine whether behavioral traits causing reproductive isolation map to the same genomic regions as the morphological traits known to correlate with mate choice. Our third aim is to detect regions of the genome causing postzygotic isolation by measuring segregation distortion at SNP markers in these pond-raised hybrids compared with that in control embryos made in the laboratory. Finally, we will test whether the same genomic regions control species differences in behavior and morphology between two independently evolved species pairs (in Priest and Paxton Lakes). Importantly, these traits will be measured in controlled outdoor experimental ponds that mimic natural lake habitats and permit the expression of natural behaviors, diets, growth, and reproductive schedules. Since the stickleback has a fully sequenced genome and many other genetic tools available, the mapping experiments proposed here will be the first step in identifying genes that underlie reproductive isolation in natural stickleback populations. In addition, the results are likely to have important implications for understanding the genetic basis of behavioral variation and behavioral disorders in humans because many of the genetic and neural pathways that underlie behaviors are likely to be conserved between fish and humans. PUBLIC HEALTH RELEVANCE: Very little is known about the genes that influence the normal range of phenotypic variation seen in human behaviors and morphologies. Humans and sticklebacks have migrated and adapted to new environments over a similar evolutionary timeframe, and genetic and developmental pathways are conserved amongst vertebrates. Thus, sticklebacks provide an excellent vertebrate model system for studying the genetic architecture of phenotypic variation that has direct relevance to similar studies in humans.