DIFFERENTIATING ECOLOGICAL AND EVOLUTIONARY IMPACTS OF SPECIES INVASIONS IN DEEP TIME: COMPARING REGIONAL EXPRESSIONS OF THE LATE ORDOVICIAN RICHMONDIAN INVASION (Invited Presentation)

Species invasions are pervasive in Earth’s history. The fossil record provides a long-term record of how invasion impacts may scale up through time, which can augment ecological studies of modern species invasions. The ecological and evolutionary consequences vary greatly among invasions, but they do so within a predictable hierarchical structure. Coordinated species invasions produce quantifiable evolutionary changes such as fostering niche evolution, differential survival of ecologically generalized taxa, faunal homogenization, and suppressing speciation.

Among the best studied coordinated species invasion events is the Late Ordovician Richmondian Invasion, which constituted a several waves of biotic invasion from multiple source regions into the Cincinnati and Nashville Basins of eastern Laurentia during the Katian Stage. The major features of this invasion were first appreciated in the early 1900’s and have received significant study since that time. General patterns of the Richmondian Invasion, including the influx of over 60 taxa that span ecological roles and taxonomic groups, the significant restructuring of paleocommunities, and differential survival of generalist taxa relative to specialist taxa, and niche evolution of taxa have been well documented. Substantial research to further delineate and clarify the details of the Richmondian Invasion has progressed on multiple fronts over the past two decades, with studies largely concentrated on the Cincinnati area.

New analyses are expanding niche stability, diversity, and invasion pathway analyses into the Nashville area. These analyses provide the opportunity to identify similarities and differences in invasion impacts during ~contemporaneous events in two discrete, but related basins. Initial analyses demonstrate substantial differences in how taxa responded to the invasion in Nashville and Cincinnati. Further examination into the causes of these differences has the potential to elucidate key issues for understanding differential impacts of modern invasions.