Collaborative Research: The age of cichlids: a fossils-to-genomes approach to dating divergence and tracing ecomorphological change in a key model of vertebrate evolution

Middle Tennessee State University, Murfreesboro TN

Investigators

Abstract

Why are some organisms more diverse than others, both in numbers and in their lifestyles? With more than 1,700 known species in rivers and lakes of the Americas, Africa, the Levant, Madagascar and India, cichlid fishes –one of the largest families of freshwater fishes– can help answer these questions. Although their evolutionary timescale is poorly understood, cichlids boast an extensive fossil record. These poorly-studied fossils could provide a window into the group’s ancient past. This project will study living and fossil cichlids to provide a better picture of when major events in cichlid evolution occurred. The project will also explore how cichlid ecology changed through time by comparing fossils with today’s living species, with the goal of understanding the life history of ancient cichlids. The project will support a postdoctoral researcher, two PhD students, a Master’s student, a technician, and undergraduate students, emphasizing development of transferable skills across STEM and non-STEM fields. The researchers will engage public audiences through university and public museums in the US, and in collaborating museums in Kenya, Brazil and the Dominican Republic. Museum-based activities and associated materials will be produced in English, Portuguese, and Spanish and shared with all participant institutions. Undergraduate teaching modules will be developed and made available as online resources for educators. Cichlid fishes represent a textbook model system for studying adaptive radiation, sexual selection, speciation, and the interplay between ecology and evolution. Despite their importance in biological research, our understanding of cichlid evolution is limited by the lack of an accurate timescale for the group’s evolutionary history. While fossils represent the principal source of temporal data in macroevolutionary studies, a barrier their incorporation is a lack of phenotypic character sets that include both extant and fossil species. Additionally, the surprisingly rich cichlid fossil record, a direct source of temporal information, remains incompletely integrated with the growing body of data available for living species. This work will produce phylogenomic data along with the first comprehensive morphological character set for cichlids, and new phenotypic data extracted from well-preserved fossil specimens. The project will: (i) leverage computed tomographic (CT) examination of modern and fossil specimens to create a morphological framework for explicitly including fossil cichlids in a phylogenetic context with living species; (ii) combine these phenotypic data for extinct and living cichlids with existing phylogenomic resources to infer a comprehensive, dated genus-level phylogeny for cichlids; and (iii) test the impact of fossils on inferred patterns of cichlid ecomorphology and macroevolution on timescales of tens of millions of years. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.