QUANTIFYING THE BIOTIC RESPONSE TO THE CLARKSVILLE PHASE OF THE RICHMONDIAN INVASION

This study establishes how biodiversity, ecospace utilization, habitat partitioning, and community composition were impacted by the primary pulse of the Richmondian Invasion. The Richmondian Invasion has been the subject of many past studies in the Cincinnati arch region, which have identified general ecological and evolutionary patterns across the entire invasion interval. However, there were discrete pulses within the larger invasion that have received less study (e.g. Clarksville Phase), largely due to the temporal constraints of the existing stratigraphic framework. However, a recently published sequence stratigraphic revision by Brett et al. provides a framework for individual invasion pulses to be studied.

The biotic impact of the Clarksville Phase was analyzed using species abundance data collected from the Waynesville Formation. Preinvasion data were collected from the Fort Ancient Member and post-invasion data were collected from the Clarksville Member. Occurrence data were collected from bedding planes for a diverse suite of invertebrate taxa using a quadrat sampling method. Data were analyzed using cluster analysis, detrended correspondence analysis, and nonmetric multidimensional scaling to establish paleocommunity composition and test for the presence of underlying ecological gradients. Environmental preferences and tolerances of taxa, richness, evenness, and guild membership were also considered.

Clear patterns of community structure change were observed before and after the Clarksville Phase of the Richmondian Invasion. This analysis improves our understanding of how the Clarksville Phase impacted habitat partitioning, community composition and structure, alpha diversity, and ecospace utilization. Understanding how this invasion pulse impacted the biota not only improves our understanding of this event but contributes to our broader understanding of biotic invasions.