Online-Talk: On Monday, November 16, 2020

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Understanding the role of environmental change in early animal evolution: New insights from geochemistry, physiology, and ocean modeling

  Lecturer: Dr. Erik Sperling

Stanford University

How environmental changes have affected the course of biological evolution is a first-order question in Earth history studies, and many important evolutionary radiations (Cambrian radiation and Great Ordovician Biodiversification Event) and mass extinctions (Ordovician-Silurian, end-Devonian and Permian-Triassic) in the Paleozoic are increasingly linked to temperature and oxygen changes in the oceans. Given that oxygen and temperature are the two most important environmental parameters in controlling habitable space for animals in the ocean, at some level there is likely a relationship between environmental change and biotic response during these events. However, geochemical patterns of change are often noisy, and it is rare for only one parameter to change in isolation. Because oxygen and temperature interact synergistically in determining an animal’s aerobic scope, it can be difficult to understand their relative importance or test the null hypothesis that environmental change is simply correlated with, rather than causally responsible for, major events in evolution. Here, data from the Sedimentary Geochemistry and Paleoenvironments Project (SGP) will be used to demonstrate how machine learning methods and an increased emphasis on accounting for sampling bias can yield a more resolved pattern of environmental change in deep time. The recently developed Metabolic Index, which relates the oxygen supply to an organism to its oxygen demand, will then be used as the physiological bridge between paleontological and geochemical datasets to test the role of oxygen and temperature change in early animal evolution.

The lecture will be broadcast on Zoom from 5 p.m. Zoom Link