Neo-sex chromosome evolution and impact on speciation-with-gene flow in oceanic island birds

进化生物学的一个主要目标是确定负责物种形成的遗传变化-新物种的形成。 大多数物种是在两个在不同地理区域进化的种群积累遗传差异，使它们在生殖上彼此不相容时形成的。 然而，有时候，物种在物种形成完成之前就进入了地理接触，产生了部分可育的杂种。 这些天然杂种具有嵌合基因组，其允许确定哪些基因和/或染色体负责生殖不相容性。 例如，以前在许多动物和植物中的研究表明，性别限制的染色体在物种形成中发挥了巨大的作用。 在所罗门群岛，两种食蜜鸟杂交并产生部分可育的杂种。 这些杂交的食蜜鸟特别令人感兴趣，因为它们拥有新旧，最近进化的性别限制染色体。 因此，蜜鸟提供了一个难得的机会来解决新物种的遗传进化，新的性别限制染色体的进化，以及性别限制染色体在物种形成中的作用等重要问题。 该项目将通过直接参与实地工作，然后进行尖端计算方法的培训，对本科生进行综合生物学教育。通过教育活动，该项目还将帮助促进一个受到全面砍伐威胁的偏远岛屿的保护。 第一个目的是描述谱系特异性进化的neo-sex染色体在两个物种的吸蜜鸟使用比较基因组学分析的高质量的基因组组装。 第二个目的是描述历史的物种形成，二次接触，混合物，和自然选择使用人口基因组学分析的样本，每个物种和它们的杂交种。 第三个目的是调查行为和遗传因素，可能会影响的方向和基因组分布的基因流使用现场数据的择偶和亲子关系。总之，这些目标结合了联合收割机基因组学和实地方法，为基因组进化和物种起源的相互作用提供了新的见解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A major goal of evolutionary biology is to determine the genetic changes responsible for speciation— the formation of new species. Most species are formed when two populations that evolve in different geographic regions accumulate genetic differences that make them reproductively incompatible with one another. Sometimes, however, species come into geographic contact before speciation is complete and produce partially fertile hybrids. These natural hybrids have mosaic genomes that allow the determination of which genes and/or chromosomes are responsible for reproductive incompatibility. Previous work in many animals and plants has shown, for instance, that sex-limited chromosomes play outsized roles in speciation. In the Solomon Islands, two honeyeater bird species hybridize and produce partially fertile hybrids. These hybridizing honeyeaters are of particular interest because they possess both old and new, recently evolved, sex-limited chromosomes. The honeyeaters therefore present a rare opportunity to address important questions in the genetic evolution of new species, the evolution of new sex-limited chromosomes, and the role of sex-limited chromosomes in speciation. The project will educate undergraduate students in integrative biology through direct involvement in field work then training in cutting-edge computational approaches. Through educational initiatives, the project will also help promote conservation in a remote island threatened by clear-cut logging.This research project has three major aims. The first aim is to characterize the lineage-specific evolution of neo-sex chromosomes in two species of honeyeaters using comparative genomics analyses of ultrahigh quality genome assemblies. The second aim is to characterize the history of speciation, secondary contact, admixture, and natural selection using population genomics analyses of samples of each species and of their hybrids. The third aim is to investigate behavioral and genetic factors that may impact the direction and genomic distribution of gene flow using field data on mate-choice and parentage. Together, these aims combine genomics and field approaches to provide novel insights into the interaction of genome evolution and the origin of species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.