Meeting Abstract
Bioluminescence is ecologically impactful through its use in communication, including courtship signals whose origins may increase rates of speciation. Therefore, learning how genes for bioluminescence originate is critical for understanding how genetic changes influence ecological communities. One origin of bioluminescence occurred in cypridinid ostracods (Crustacea), some of which employ complex bioluminescent courtship displays that differ among dozens of species. Cypridinid bioluminescence involves a novel enzyme (c-luciferase) with two deeply conserved sequences, both Von Willebrand Factor D (VWD) domains. We characterized the history of VWD to inform the origin of this novel gene. We analyzed VWDs in animal genomes, finding them as parts of many different genes with distinct domain architectures. We next included VWDs from ostracod transcriptomes and a draft genome, and discovered c-luciferase originated through novel fusion of distantly related VWD domains. Unexpectedly, we found VWDs proliferated in ostracods before the origin of bioluminescence. Many of these genes contain highly repetitive elements, suggesting a chaotic evolutionary history. Although we still have much to learn about the function of genes related to c-luciferase, this mode of gene origin may be similar to Innovation Amplification Duplication (IAD), but with different timing. Our results illustrate how contingent, unpredictable genomic histories contribute to new genes and ecologically impactful, sometimes beautiful, phenotypes.
