ANALYSIS OF AN ANCIENT INVASION ILLUMINATES ANTHROPOCENE ISSUES

In today’s globally connected world, biotic invasions are commonplace due to global trade moving taxa outside their native ranges and changing climate allowing range expansion. Thus, developing a holistic understanding of how biotic invasions impact ecosystems over different timescales is vital and can be achieved by combining short term observations from modern ecosystems with long term patterns in the fossil record. The Late Ordovician (Katian) Richmondian Invasion has been the subject of prior analyses which focused on this invasion primarily as a single interval and established general ecological and evolutionary patterns across the entire invasion. However, recent sequence stratigraphic refinement has made analysis of individual invasion pulses possible.

This work examines the first successful pulse of the invasion, termed the Clarksville Phase, using occurrences of macrofaunal invertebrate fossils collected from the Waynesville Formation. Data were collected using a quadrat method and provide coverage of the preinvasion, invasion, and post-invasion intervals across a range of depositional environments. A suite of analyses were conducted to comprehensively examine the impacts of the Clarksville Phase. Results indicate shifts in diversity, paleocommunity composition, ecospace utilization, and niche stability following the introduction of the Clarksville invaders into the basin. This work provides a valuable case study of how climate change can facilitate invasion, how the progression of that invasion can be modulated by continued climate fluctuation, how ecosystems accommodate invaders, and how the autecology of both the invaders and incumbents influence the impact of the invasion on the recipient biota on millennial time scales.