Rather than traditional experimental approaches in ocean acidification (OA) research, we propose a modern approach incorporating phylogenetics, as well as diversification and biogeographical analyses, in a paleoacidification framework. In this thesis we reconstruct an expanded and time-calibrated species-level phylogeny for a prime model group, coralline red algae subclass Corallinophycidae, in an effort to link the effect of paleoacidification on corallines as an analogue to projected acidification. Several methodologies are employed in an attempt to detect phylogenetic signatures of diversification rate shifts that can be linked in geological time to mass extinctions and associated acidification events. We find evidence that three extinctions (Late Cretaceous, Paleocene-Eocene, and Eocene-Oligocene) resulted in rate shifts, exemplifying the detrimental nature of OA for corallines. To heighten our perspective on the age of the corallines, we conduct an exploratory study implementing different model settings and parameters on a dataset from a prior publication that presented conflicting results for the age of corallines, and we provide contrasting dates that call for more research into this issue. Furthermore, biogeographical analyses indicate that Corallinophycidae had origins in the Central Indo-Pacific, and help to reveal details of the evolutionary story of this model group.
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