DISSERTATION RESEARCH: The evolutionary origin and genetics of color pattern diversity in Phyllobates poison frogs

该项目将确定导致不同毒镖蛙之间颜色模式差异的基因。这些青蛙以色彩鲜艳的图案而闻名，这些图案可以作为警告信号来威慑潜在的捕食者。在一小群毒镖蛙(叶飞蛙)中，鲜艳的明亮黄色的颜色是从黑暗的条纹祖先独立进化出来的多次；在一个物种中，不同的颜色变形甚至出现在同一种群中。研究人员将利用新的基因组技术和统计分析来识别条纹青蛙和纯色青蛙之间的差异基因。这些结果将为这组青蛙颜色模式变异独立进化的遗传过程提供关键的见解。这项研究还将揭示有益的基因突变在种群内和种群间传播的重要信息。此外，该项目还将为本科生提供研究机会。计划的外展活动包括为中小学生举办的公共研讨会和教育活动。为了查明导致叶球目物种趋同进化的遗传因素，这个项目利用了个体发育、种间和种内颜色模式的差异。首先，在来自哥伦比亚圣胡安河上游的两对密切相关的叶藻谱系之间以及在一个种群内的金色叶藻之间存在着显著的颜色变化。研究人员将使用外显子丰富和下一代测序来寻找在条纹和纯色谱系之间高度区分的基因座，并在统计上与奥氏青霉的颜色模式变化相关联。其次，将使用RNAseq研究着色发育过程中的基因表达，以便识别在整个发育过程中发生着色变化时上调或下调的基因。这两种方法将产生一组可能存在于叶柄藻类颜色模式变异背后的基因座。然后，研究人员将结合分子系统发育和合并模拟来推断这些基因座的进化史，以阐明这群青蛙亮黄色趋同进化背后的遗传机制。

This project will identify the genes responsible for color pattern variation between different Poison-dart frogs. These frogs are well known for their brightly colored patterns, which serve as warning signals to deter potential predators. Within one small group of Poison-dart frogs (Phyllobates), vivid bright yellow colorations have independently evolved multiple times from dark, striped ancestors; in one species, different color morphs even occur within the same population. The researchers will take advantage of new genomic technologies and statistical analyses to identify the genes that differ between striped and solid-colored frogs. Results will provide critical insights on the genetic processes that underlie the independent evolution of color pattern variants in this group of frogs. The research will also reveal important information on the spread of beneficial genetic mutations within and across populations. In addition, the project will provide research opportunities for undergraduate students. Planned outreach includes public seminars and educational activities for elementary and middle school children. To pinpoint the genetic elements responsible for convergent evolution across Phyllobates species, this project takes advantage of ontogenetic, interspecific, and intraspecific variation in color pattern. First there is striking variation in color pattern between two pairs of closely related Phyllobates lineages, and within a population of Phyllobates aurotaenia from the upper San Juan River in Colombia. The researchers will use exon enrichment and next-generation sequencing to find loci that are highly differentiated between striped and solid-colored lineages, and statistically associated with color pattern variation within P. aurotaenia. Second, gene expression during coloration development will be studied using RNAseq, in order to identify genes that are up or down-regulated when changes in coloration occur throughout development. These two approaches will yield a set of putative loci behind color pattern variation in Phyllobates. The researchers will then use a combination of molecular phylogenetics and coalescent simulations to infer the evolutionary history of these loci, in order to shed light on the genetic mechanisms behind the convergent evolution of bright yellow coloration in this group of frogs.