Genomics of the Globally Distributed Echinoid Genus Tripneustes
Understanding genomic divergence can be a key to understanding population dynamics. As global climate change continues it becomes especially important to understand how and why populations form and dissipate, and how they may be better protected. To this effect, the globally distributed sea urchin genus Tripneustes has been highlighted as an ideal group for studying patterns of genomic divergence as the global distribution is split into two physically separated species (T. ventricosus in the Atlantic and T. gratilla the Pacific), and cryptic divergence in the absence of hard physical barriers has been suspected within each ocean. In an effort to better characterize the spatial divergence of this economically and ecologically important echinoid, microsatellite genotyping and mitochondrial COI sequence fragments collected from over 1,200 individuals across the Indo-Pacific were compared. Following isolation and sequence confirmation, the mitochondrial genome of T. gratilla was next compared to all previously published sea urchins mitochondrial genomes. To address questions regarding the more nuanced molecular differences and broader evolutionary trajectories within the genus a draft transcriptome for the species T. gratilla was generated. Finally, utilizing annotated genes of known functional importance identified from the transcriptome, targeted bait capture was employed to generate a reduced representative genome for individual Tripneustes from across the distribution of the genus. Divergence across this distribution in genes involved in fertilization, immune system function, and environmental stress response are highlighted.