Niche stability in Late Ordovician articulated brachiopod species before, during, and after the Richmondian Invasion

In this study, the relative niche stability of Late Ordovician articulate brachiopod species from the Cincinnati Arch was analyzed before, during, and after an immigration of extra-basinal taxa into the region, known as the Richmondian Invasion. The primary hypothesis investigated with this project is whether species preserve (via niche conservation) or alter (via niche evolution) the parameters of their ecological niche during intervals of biotic (invasive regime) vs. abiotic change (gradual environmental change). Ecological niche modeling (ENM), a process that utilizes computer-based algorithms to mathematically estimate a species ecological niche, was employed to test this hypothesis. Additionally, the efficacy of using the ENM program Maxent with fossil data was tested against a well-established ENM method (GARP). Results indicate that during intervals of gradual change, species conserved the parameters of their ecological niches to higher degrees than during intervals of ecological rapid biotic change, when niche evolution was common. Native and invasive species displayed congruent patterns of niche stability, but niche conservatism was more common in broadly adapted generalist species than ecological specialists.