LINKING EARTH-SYSTEM CHANGE WITH SPECIATION PROCESSES DURING THE GREAT ORDOVICIAN BIODIVERSIFICATION EVENT (GOBE) (Invited Presentation)

The Ordovician Period was a time of intense biotic change including dramatic radiation of marine life and development of new ecosystem structures, during the Great Ordovician Biodiversification Event (GOBE) but ultimately culminating in the Late Ordovician Mass Extinction (LOME). Over the past two decades, an international network of scientists have intentionally collaborated and worked independently to develop detailed datasets to constrain both the pattern and processes of the Great Ordovician Biodiversification Event (GOBE), which is the primary diversification phase of the Ordovician Radiation. In this presentation, I will highlight recent developments as well as areas for future research development.

Diversification patterns discerned from both global databases, when subjected to rigorous sample standardization protocols, and regional- and basinal-scale studies indicate that the primary interval of biotic change occurred in the Mid-Ordovician. This timing notably overlaps with the development of more complex paleocommunity structures and increased skeletal production. These biotic changes co-occurred and were facilitated by a diverse array of environmental changes including cooling global temperatures, tectonic shifts, increasing oxygenation, increased nutrient supply from continental weathering and volcanism, and change in global ocean circulation.

Better constraining the linkages between the earth and life system is essential for fully understanding how the drivers of diversity change and ecosystem establishment in earth history. One method for linking earth and life changes is via phylogenetically-informed model-based biogeographic and speciation analysis. Because facilitating speciation processes are foundational for increasing diversity, understanding how dispersal and isolation mechanisms operated during the GOBE elucidates mechanism for diversity accumulation through time. Notably, vicariance and dispersal speciation alternate during this interval following the Biotic Immigration Event (BIME) model. This links speciation directly to sea-level, climatic, and tectonics events. Expanding direct studies of speciation and expanding our knowledge of undersampled geographic regions will produce new insights on the GOBE.