2014 Annual Science Report
Massachusetts Institute of Technology Reporting | SEP 2013 – DEC 2014
Early Animals: The Origins of Biological Complexity
The focus of the Erwin group remained on the origins of novelty and innovation, particularly associated with the origin and early diversification of animals during the Cryogenian, Ediacaran and early Cambrian. A field campaign in Namibia yielded new specimens, new fossil localities, and a potential new organism from the Ediacaran. Work on the phylogeny of early Cambrian lobopods was carried out to the hypothesis that arthropods evolved from this enigmatic group of organisms.
The focus of the Erwin group remained on the origins of novelty and innovation, particularly associated with the origin and early diversification of animals during the Cryogenian, Ediacaran and early Cambrian. Sarah Tweedt, a Ph.D. candidate advised by Douglas Erwin, is working to better understand the origins of development and major developmental change in in the earliest history of multicellular organisms and animals. The early Cambrian lobopods are widely thought to have given rise to all true arthropods, but this would imply a substantial and rapid evolutionary transition in limb development. In 2014, Sarah began to generate a more expansive and thorough morphological dataset for lobopod fossils, with the goal of using these data to determine a more robust lobopod-arthropod phylogeny, and ultimately to help understand major developmental change in the ancient panarthropod lineage. Uniquely, her study will use modern animal developmental principles as a model for collecting and organizing fossil morphological data, and will explore the application of Bayesian phylogenetic approaches to reconstruct fossil relationships based on morphology. Sarah traveled to Copenhagen in the spring of 2014 to study the lobopod material from the Sirius Passet of North Greenland, and she has recently been awarded a Cosmos Scholars Grant (Cosmos Club Foundation, Washington DC) for travel to study additional lobopod fossil material this year. She presented some preliminary phylogenetic work at the annual Geological Society of America meeting in the fall of 2014.
Sarah also conducted field work in Namibia (accompanying Marc Laflamme and Simon Darroch) in the summer of 2014 to continue her study of the Ediacara biota. She returned to field sites visited in 2013 and collected 80+ specimens of a potential new macroscopic Ediacaran organism. The field team also discovered new fossil localities and continue to research the faunal compositions of the latest Ediacaran in order to better understand the Ediacaran-Cambrian transition.
Prof. Ariel Chipman from the Hebrew University of Jerusalem is a visiting sabbatical researcher. He is interested in understanding the evolution of the arthropod body plan by synthesizing data from developmental biology (the focus of his research at the Hebrew University) and from the fossil record. During his sabbatical he is studying Cambrian arthropod fossils to map the appearance of key developmental events and gene regulatory networks on a phylogenetic tree of stem group arthropods.
Finally, Doug Erwin has spent the past year focusing on issues associated with the origins of evolutionary novelty and innovation. Part of this work, on the role of public goods in evolutionary innovation is in press at Geobiology. Other work, including a conceptual framework for innovation and novelty, will be published in 2015.