Transcriptome phylogenies support ancient evolutionary transitions in bioluminescence traits of cypridinid ostracods

Abstract

AbstractBioluminescence evolved many times independently, leading to dramatic effects on ecosystems by influencing communication both within and between species. One origin of bioluminescence is within cypridinid ostracods. Bioluminescent cypridinids probably all use light as an anti-predator display, while a subset that diversified in the Caribbean also use light for courtship signaling. Despite their importance for understanding the evolution of bioluminescence, very little molecular phylogenetic data are available for cypridinids and the timing of evolutionary transitions of luminous traits is poorly understood. Here, we estimate the first transcriptome-based molecular phylogeny and divergence times of Cypridinidae. Our results strongly support previous hypotheses of a single origin of bioluminescent courtship signaling, nested within a single origin of bioluminescence, and the secondary loss of courtship signaling in Vargula tsujii. We propose the name Luminini for the Tribe of bioluminescent cypridinids and Luxorina for the Sub-tribe of cypridinids with courtship signaling. Our relaxed-clock estimates of divergence times coupled with stochastic character mapping show luminous courtship evolved at least 151 Million Years Ago (MYA) and cypridinid bioluminescence originated at least 197 MYA, making it one of the oldest documented origins of bioluminescence. The molecular phylogeny of cypridinids will serve as a foundation for integrative and comparative studies on the biochemistry, molecular evolution, courtship, diversification, and ecology of cypridinid bioluminescence.