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导致物种形成（新物种的形成）的基因变化。当两个在不同地理区域进化的种群积累了遗传差异，使它们在繁殖上互不相容时，大多数物种就形成了。然而，有时物种在物种形成完成之前就已经在地理上接触，并产生部分可育的杂交后代。这些天然杂交种具有马赛克基因组，可以确定哪些基因和/或染色体负责生殖不相容。例如，先前对许多动物和植物的研究表明，性别限制的染色体在物种形成中发挥着巨大的作用。在所罗门群岛，两种蜜水鸟杂交并产生部分可育的杂交后代。这些杂交的蜜蜂特别有趣，因为它们既有旧的，也有新的，最近进化的，性别限制的染色体。因此，蜜蜂提供了一个难得的机会来解决新物种的遗传进化、新的性别限制性染色体的进化以及性别限制性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和尖端计算方法的培训来教育本科生整合生物学。通过教育活动，该项目还将有助于促进一个受到滥伐威胁的偏远岛屿的保护。这个研究项目有三个主要目的。第一个目的是利用超高质量基因组组装的比较基因组学分析来表征两种蜜蜂中新性染色体的谱系特异性进化。第二个目标是通过对每个物种及其杂交样本的种群基因组学分析来描述物种形成、二次接触、混合和自然选择的历史。第三个目的是利用野外交配选择和亲代数据，研究可能影响基因流方向和基因组分布的行为和遗传因素。总之，这些目标结合了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。该奖项反映了美国国家科学基金会的法定使命，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.