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

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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.