Drivers and constraints of rapid adaptive diversification in Lake Poso ricefishes, an emerging model species flock

波索湖稻鱼（一种新兴模式物种群）快速适应性多样化的驱动因素和限制因素

• 批准号: 466783002
• 负责人: Dr. Astrid Böhne
• 金额: --
• 依托单位: Zentrum für Molekulare Biodiversitätsforschung (zmb)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/466783002?language=en
• 关键词: Drivers; constraints; rapid; adaptive; diversification

Evolutionary radiations, that is the increase of species diversity in a clade, have given rise to the bulk of biodiversity. Yet the processes shaping radiations remain an area of active research and controversial discussion. Species flocks endemic to habitat islands allow studying the genomic background of adaptive divergence, including processes of reticulate evolution. Ecological opportunity is considered as the main driver of “adaptive radiation”, but appears insufficient to explain why lineages differ in their ability to adapt and diversify. Hybridization of related lineages can increase genetic and phenotypic variation, which in turn can facilitate population divergence in response to divergent selection. Here, we test hypotheses on the roles of ecological opportunity and hybridization in adaptive diversification in a single, small system closely related to one of the major vertebrate model organisms, the medaka (Oryzias latipes). The monophyletic species flock of three Oryzias ricefish species is endemic to ancient Lake Poso in Sulawesi, Indonesia. We test if ecological speciation can explain divergence of Lake Poso Oryzias, and hypothesize that competition with a sympatric but not closely related ricefish lineage constrained the spectrum of adaptation. We further test if hybridization of the lake fishes with stream populations affected lake fish evolution in interplay with ecological opportunity. Pilot data collected in the field suggest that the three Oryzias show largely distinct ecological niches, matching differences in their morphology, and in functional traits of trophic relevance. The data also suggest that their habitat niches are complementary to the sympatric ricefish lineage. We will further extend these observation data by implementing ROV-based transect methods, in order to characterize habitat use in in detail – based on sound sample sizes, and covering deep and offshore habitats. Fieldwork moreover revealed a potential hybrid population, which might account for signals of genomic introgression. Preliminary RADseq data distinguish the three lake species, and suggest relatedness of the potential hybrid fish with two of the lake species. The extended sampling and sequencing approach proposed, covering potential parental populations from habitats close by the lake, will enable appropriate testing of the hybridization hypothesis benefitting from the close relatedness of the Oryzias flock to the model organism medaka. The complementary in-depth approaches will deliver a comprehensive understanding of the evolutionary history, and the drivers of adaptive divergence in the small Lake Poso Oryzias species flock.

进化辐射，即一个进化支系中物种多样性的增加，产生了大部分的生物多样性。然而，形成辐射的过程仍然是一个活跃的研究和有争议的讨论领域。栖息地岛屿特有的物种群允许研究适应性分化的基因组背景，包括网状进化过程。生态机会被认为是“适应性辐射”的主要驱动因素，但似乎不足以解释为什么谱系在适应和多样化能力方面存在差异。亲缘谱系的杂交可以增加遗传和表型变异，这反过来又可以促进群体分化，以响应分化选择。在这里，我们在一个与主要脊椎动物模式生物之一——medaka （Oryzias latipes）密切相关的单一小系统中测试了生态机会和杂交在适应性多样化中的作用的假设。三种米鱼的单系物种群是印度尼西亚苏拉威西岛古波索湖特有的。我们测试了生态物种形成是否可以解释Poso Oryzias湖的分化，并假设与同域但不密切相关的米鱼谱系的竞争限制了适应范围。我们进一步测试了湖泊鱼类与河流种群的杂交是否在生态机会的相互作用下影响了湖泊鱼类的进化。在野外收集的试验数据表明，这三种稻属植物表现出截然不同的生态位，在形态和营养相关的功能性状上具有匹配的差异。数据还表明，它们的生境与同域稻鱼谱系是互补的。我们将进一步扩展这些观测数据，采用基于rov的样带方法，以声音样本量为基础，覆盖深海和近海栖息地，以详细表征栖息地的使用情况。田野调查还发现了一个潜在的杂交群体，这可能解释了基因组渗入的信号。初步RADseq数据区分了三种湖泊物种，并表明潜在杂交鱼与其中两种湖泊物种有亲缘关系。提出的扩展采样和测序方法，涵盖了靠近湖泊栖息地的潜在亲代种群，将使杂交假说得到适当的检验，这得益于Oryzias群与模式生物medaka的密切关系。互补的深入方法将提供对Poso Oryzias小物种群的进化史和适应分化驱动因素的全面理解。