Bioluminescence, a phenomenon hypothesized as vital in mating behavior, species recognition, prey attraction, and predator avoidance, is pervasive in deep sea fishes. Despite broad biological significance, no study to date has directly tested whether the evolution of bioluminescent systems is concordant with increased rates of evolution. This research project will focus on an ideal model system for comparing rates of evolution in luminescent versus non-luminescent species. The evolutionary relationships of bioluminescent fishes in the Order Alepocephaliformes will be reconstructed using a combination of DNA sequence data and morphological features, including anatomy of the light-organ system. The resulting set of relationships will be used to test for changes in evolutionary rate between the bioluminescent and non-luminescent species.
This project will provide new insights into the evolution and diversification of the complex light-organ system in fishes, and more broadly, the forces shaping deep-sea fish biodiversity. The "alien nature" of the deep sea and its inhabitants provides an excellent system for engaging public interest in biology. Results will be disseminated via public outreach and education programs.
Bioluminescence, a phenomenon hypothesized to be vital in mate selection, species recognition, prey attraction, and predator avoidance, is pervasive in the deep sea across such disparate groups as copepods, ctenophores, cnidarians, squids, and fishes. Despite broad biological significance, no study to date has directly tested whether the evolution of bioluminescent systems is correlated with increased rates of diversification. Based on the study of existing museum collections and novel alepocephaliform material collected by the PI and co-PI, the phylogenetic relationships of the deep-sea fish order Alepocephaliformes was reconstructed. Two morphologically distinct families comprise the Alepocephaliformes, the bioluminescent tube-shoulders (family Platytroctidae) and the primarily non-luminescent slickheads (family Alepocephalidae), and, as such, the order provides an ideal model system for comparing rates of diversification in luminescent versus non-luminescent sister clades. This project provided new insights on the interrelationships of alepocephaliform fishes, as well as the evolution and diversification of a complex light-organ system in platytroctids, comprising both a unique tube-like shoulder organ, which contains luminous fluid that can be excreted into the environment, and numerous photophores that vary ontogenetically. A robust phylogeny for Alepocephaliformes was generated based on a suite of nuclear and mitochondrial markers. The resulting phylogenetic hypotheses recovered both Alepocephalidae and Platytroctidae as monophyletic, and will be used to further investigate alepocephaliform interrelationships, reconstruct the evolution of the luminescent system in Platytroctidae, as well as test for evolutionary rate shifts between bioluminescent and non-bioluminescent sister clades.
