Evolution of modern fish faunas: origins, phylogeny, biogeography and environmental adaptations

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Fish represent well over 50% of all living vertebrates: they are extremely diverse and found in almost every aquatic habitat. They are commercially valuable as a major food source, as well as in the aquarium trade, and for recreational fishing. Despite their value, there is still a great deal unknown about the evolutionary relationships among many lineages, and how they adapted to their current habitats. This research proposal is to study key lineages of fish from the last 100 million years of life. This period spans a time of major adaptive radiation of different groups of fish as well as the mass extinction event at the end of the Cretaceous when the dinosaurs went extinct. Many fish lineages survived this extinction event, and others arose after the end-Cretaceous when new habitats became available with extinction of earlier forms. This mix of survivors and new species form our modern fish faunas. Study of the fish from the last 100 million years is important for understanding the evolution and distribution in geographic space and through geological time (historical biogeography) of modern fish. Fish are of particular biogeographical interest as they are limited in their dispersal abilities based on freshwater connections, abyssal sea depths, and land barriers, and so they are good indicators of past terrestrial and seaway connections, and past environmental conditions. We will study fish from about 9518 million years ago and compare them with living members of their lineages, in order to describe new forms and to document their adaptive diversity, determine their relationships, and understand how they came to be distributed in their current ranges and habitats. Many of the fish we will study are from commercially important groups, including the shads, herrings and anchovies. These studies will allow an understanding of how fish lineages adapted to changing environmental conditions in the past, and how they may respond to future environmental change. The new fossil fish that will be studied for this proposal will provide new avenues for exploration of the diversity of fishes before and after the end-Cretaceous extinction event, and give us an understanding of the adaptations of fish faunas to changing environments. Significant results expected of this proposal are to increase the number of fossil fish species known with descriptions of new taxa, to elucidate relationships among lineages previously unstudied, and to propose novel ideas on the evolution and changing environments that helped shape our modern fish faunas.