Davis Lab

Evolution of Deep-Sea Fishes

Research in the lab  focuses on the evolution of fishes that inhabit the deep sea, as the extreme habitats of this environment have produced fascinating evolutionary events among the 4000 - 6000 species of marine fishes that have invaded this realm (e.g., telescopic eyes, bioluminescence, hermaphroditism). We use phylogenetic hypotheses as frameworks to investigate a breadth of evolutionary questions related to organismal diversity and diversification. Our work focuses on exploring a number of evolutionary topics related to fishes that inhabit the deep sea, including; estimating divergence times, temporal changes in diversification rates, character evolution, correlations between speciation rates and evolutionary adaptations, ecological habitat shifts, and biogeography.


Our new lab paper on the evolution of pearleye fishes (Aulopiformes: Scopelarchidae) was recently published in the journal Copeia. This study investigates the evolutionary relationships among pearleye species with molecular (eight genes) and morphological data. A new genus of pearleye is diagnosed, Lagiacrusichthys, from a previously described species (Benthalbella macropinna) distributed in Antarctic waters. 

A specimen of Lagiacrusichthys under fluorescent lighting and modified to a blue hue.

The newly recognized antarctic genus Lagiacrusichthys is named for a wyvern, a dragon-like creature, specifically the sea-wyvern Lagiacrus (made famous by Monster Hunter), known for his fierceness and for inhabiting the deep. As both are rather ferocious coldwater predators, I named Lagiacrusichthys after the fictional monster Lagiacrus. In a remarkable coincidence, the paper diagnosing Lagiacrusichthys was released during the same week as the newest entry in the Monster Hunter series, Monster Hunter 4 Ultimate.

The sea-wyvern Lagiacrus from the Monster Hunter series of games.

The sea-wyvern Lagiacrus from the Monster Hunter series of games.

Pearleyes are known for their dorsally directed tubular and semi-tubular eyes, which allow them to hunt prey above them in the water column. Pearleye fishes possess an array of visual specializations associated with living in the deep sea, including that their tubular eyes are highly capable of observing bioluminescent light, with the ability to pinpoint bioluminescent emissions from a distance of at least six meters. 

Original Source: Davis, M.P. (2015). Evolutionary Relationships of the Deep-Sea Pearleyes (Aulopiformes: Scopelarchidae) and a New Genus of Pearleye from Antarctic Waters. Copeia. 103(1):64-71.

Funding for this work was provided by the National Science Foundation (DEB 1258141 and 106086) and the American Museum of Natural History Lerner-Grey Marine Research Grant.

St. Cloud State University, 720 4th Ave South, Wick Science Building, St. Cloud, MN 56301. © MP Davis 2016