• Creating the Future

    The Hector Fellow Academy initiates innovative research projects on latest scientific problems.

Speciation and population dynamics in the mesopelagic zone

Eva Paulus – Hector Fellow Axel Meyer

Mesopelagic fishes are an important part of the deep pelagic ecosystem in the world’s oceans. During my PhD thesis, I will collect and genomically investigate an especially abundant and little-studied order of fishes, the Stomiiformes. I will strive to learn whether and how their populations are genetically connected in their open-ocean habitat. I will aim to identify isolating barriers that are important for speciation and ask whether gene flow can occur over large distances.

The deep sea is least studied ecosystem on Earth and every research expedition still uncovers new species. The mesopelagic zone (200-1000m) is located below the sunlit epipelagic zone, a transition layer beneath which lies the bathypelagic. The mesopelagic links the surface waters to the deep ocean, not only as part of the food web, but also in terms of carbon sequestration. The order of stomiiform fishes lives in all oceans - comprising dragonfishes, lightfishes, hatchetfishes and bristlemouths – and is abundant and diverse in terms of species. Little is known about the population structure of these fishes, i.e. how well their populations are connected and thereby how speciation can occur since traditional models of speciation require barriers to gene flow so that necessary genetic differences can accumulate for speciation to occur. Eggs and larvae are widely distributed by ocean currents, tending to increase dispersal, migration, and gene flow and might genetically connect populations across oceans. In my project, I will investigate these fishes using modern genomic techniques, such as whole-genome and RAD-sequencing, to better understand their evolutionary relationships and to learn how population structure differs between species with markedly different life-histories, e.g. if they vertically migrate or not. During my first year, I will collect mesopelagic fishes on a research cruise in the Atlantic.