Developing a phylogenetic framework for tiny Ordovician brachiopods (Atrypida: Anazyginae and Catazyginae) from the eastern United States

Abstract

Elucidating how environmental change can facilitate the differentiation of evolutionary lineages and the establishment of new species is a critical issue for understanding both the history of life and modern biota. Notably, speciation events are known to be the main drivers of bio - diversification; thus, generating well-constrained phylogenetic hypotheses to investigate speciation processes and facilitators can provide key data on links between biogeography, speciation, and diversification. During the Great Ordovician Biodiversification Event (GOBE), articulate brachiopods were a key group on the rise. By the Middle to Late Ordovician, the brachiopod order Atrypida was no exception. The atrypids diversified greatly and established evolutionary novelties such as helical and calcite-supported lophophores. The Ordovician epi - continental seas in eastern Laurentia provided an excellent environment for reproductive isolation and speciation, with sea-level fluctuations, ideal climate conditions, and active tectonic settings. However, speciation patterns and drivers within two widely-distributed atrypid sub - families, Anazyginae ( Anazyga spp. and Zygospira spp. ) and Catazyginae ( Catazyga spp. ) , remain poorly known. In this project, we seek to develop a robust phylogenetic framework for these clades and use that framework to evaluate speciation processes and facilitators during the Late Ordovician. Morphological data will be collected from published