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的基因变化--新物种的形成。当在不同地理区域进化的两个种群积累了遗传差异，使它们在繁殖上彼此不相容时，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会在地理上发生接触，并产生部分可育的杂交后代。这些天然杂交种具有镶嵌基因组，可以确定哪些基因和/或染色体是造成生殖不亲和性的原因。例如，之前在许多动植物上的研究表明，性别受限的染色体在物种形成中扮演着非常重要的角色。在所罗门群岛，两种蜜鸟进行杂交，并产生部分可繁殖的杂交后代。这些杂交蜜鸟特别令人感兴趣，因为它们同时拥有新旧两种、最近进化的、性别受限的染色体。因此，蜂蜜提供了一个难得的机会来解决新物种遗传进化中的重要问题，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。该项目将通过直接参与实地工作来教育本科生综合生物学，然后培训尖端计算方法。通过教育倡议，该项目还将有助于促进一个受到砍伐威胁的偏远岛屿的保护。该研究项目有三个主要目标。第一个目标是利用超高质量基因组组合的比较基因组学分析来描述两种蜜鸟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物种的样本进行种群基因组分析，来表征物种形成、二次接触、混合和自然选择的历史。第三个目标是使用关于配偶选择和亲子关系的现场数据来调查可能影响基因流动方向和基因组分布的行为和遗传因素。这些目标结合了基因组学和领域方法，为基因组进化和物种起源的相互作用提供了新的见解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.