Dimensions US-China: Allosomes: An Unexplored Dimension of Biodiversity

尽管经过了150多年的科学研究，我们对物种形成机制的理解仍然不完整。早期的研究强调地理隔离对限制种群间基因流动的重要性。没有基因流动，种群可能会在很长一段时间内进化成新的物种。最近的研究集中在自然选择在加速物种进化中的作用，无论种群之间是否有基因流动。这个项目测试了一个新的想法，即新的同种体的快速进化可以加速某些谱系的物种形成速度。研究人员将把重点放在世界各地热带地区发现的异常多样化的慈鲷谱系上。已知的慈鲷超过2000种，使它们成为现存脊椎动物中物种形成最快的谱系。最近的研究揭示了这些鱼类同种异体中意想不到的多样性。这种多样性可能是由于一种独特的行为，雌性用嘴产卵和幼虫长达三周。男性和女性在行为和生理上的相关差异导致了有利于男性和女性的不同基因变化。这种模式被称为基因冲突。这个项目将检验这样一个假设，即这些基因冲突是导致新同种体快速进化的原因。反过来，这种快速进化被认为对这个群体的快速物种形成很重要。该项目将促进美国、欧洲、中国和巴西之间的科学交流。它还将为马里兰大学的本科生提供研究培训机会。研究人员将使用基因组技术来表征来自非洲和南美洲的慈鲷鱼的同种异体。男性和女性之间的遗传分化区域将使用全基因组DNA测序来确定。长读测序技术将用于表征同体进化早期阶段染色体序列和结构的变化。比较系统发育分析将用于确定高同体更替率是否与生活史性状有关。具体的焦点性状是雌性口育，这与雌雄之间的拮抗选择有关。为了确定同种异体的进化变化是否会产生遗传不相容，研究人员将测量具有不同同种异体的物种之间的杂交适应度。这些数据将允许对同种异体进化机制的理论预测进行测试。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。

Despite more than 150 years of scientific study, our understanding of the mechanisms of speciation is still incomplete. Early work emphasized the importance of geographic isolation to limit gene flow among populations. Without gene flow, populations might then evolve into new species over long periods of time. More recent work has focused on the role of natural selection in accelerating the evolution of species, with or without gene flow among populations. This project tests a new idea, that the rapid evolution of new allosomes can accelerate the rate of speciation in some lineages. The researchers will focus on the exceptionally diverse lineage of cichlid fishes found in tropical areas around the world. More than 2,000 species of cichlid fishes are known, making them the most rapidly speciating lineage of extant vertebrates. Recent work has revealed unexpected diversity in the allosomes of these fishes. This diversity may be due to a unique behavior in which females mouthbrood eggs and larvae for periods of up to three weeks. The associated differences in behavior and physiology between males and females causes different genetic changes to be favored in males and females. This pattern is known as genetic conflict. This project will test the hypothesis that these genetic conflicts are responsible for the rapid evolution of new allosomes. In turn, this rapid evolution is thought to be important in the rapid rate of speciation in this group. The project will promote scientific exchange between the U.S., Europe, China and Brazil. It will also provide research training opportunities for undergraduate students at University of Maryland. The researchers will use genomic techniques to characterize allosomes in cichlid fishes from Africa and South America. Regions of genetic differentiation between males and females will be identified using whole-genome DNA sequencing. Long-read sequencing technology will be used to characterize changes in the sequence and structure of chromosomes during the early stages of allosome evolution. Comparative phylogenetic analysis will be used to determine whether high rates of allosome turnover are associated with life history traits. The specific focal trait is female mouthbrooding, which correlates with antagonistic selection between males and females. To determine whether evolutionary changes in allosomes create genetic incompatibilities the researchers will measure the fitness of hybrids between species with different allosomes. These data will allow theoretical predictions about the mechanisms of allosome evolution to be tested.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.