Collaborative Research: EAGER: The early evolution of lamp shells and relatives (brachiopods) using an integrated approach combining genomics and fossils

Stanford University, Stanford CA

Investigators

Abstract

Lamp shells and relatives (brachiopods) are marine animals that are one of the world's oldest forms of multicellular organisms. Although no longer numerous today, brachiopod species were a dominant component of marine ecosystems 540-250 million years ago. Because of their mineralized shells, brachiopods have a high chance of being preserved as fossils, and have one of the most complete fossil records of any animal group. This project aims to solve a long-standing debate regarding how different brachiopod groups are related to each other and to other animals. Living brachiopods from North America, Croatia, Japan, New Zealand, and several other localities around the world will be sampled for genetic material that will be used to reconstruct evolutionary relationships among brachiopods. These genetic data will then be combined with data from their rich fossil record to test whether rates of evolution were higher during the Cambrian period than during more recent time periods. Several workshops will be organized to train a new generation of early career scientists in a diversity of genomic and paleontological methods. This project will also develop new instructional videos and accompanying lesson plans designed to teach high school science students how to build earth science content from a biological foundation. Brachiopods are amongst the first mineralized metazoans to appear in the fossil record during the Cambrian, yet agreement about the phylogenetic relationships among these early forms is still unknown. While the brachiopod fossil record will ultimately be key to determining character homology and polarity during the evolution of the distinctive brachiopod body plan, correctly reading this record has been difficult due to disagreement about relationships among the living clades. This project will use an integrated approach to understand the phylogeny of brachiopods and macroevolutionary patterns of early animal evolution. First, a widespread fieldwork campaign will collect brachiopod specimens suitable for high-quality RNA extraction and transcriptome sequencing. These data will form the basis for the heart of this study: the first phylogenomic study of brachiopods, which will result in a robust phylogenetic framework for the modern clades. Second, a comprehensive morphological database for living and fossil brachiopods will be constructed and calibrated using a molecular clock. These molecular and morphological data sources will be combined to test hypotheses of morphological and molecular evolution during the rapid diversification of form during the Cambrian radiation.