New paper on the timing and geological context of two co-evolving salmonid fish radiations (predator-prey system) driven by adaptation-to-depth in the Great Lakes: www.nature.com/articles/s42...

Origin of the Laurentian Great Lakes fish fauna through upward adaptive radiation cascade prior to the Last Glacial Maximum - Communications Biology

Laurentian Great Lakes fish diversification predates the Last Glacial Maximum and was likely driven by novel habitats and predator–prey dynamics.

We think the diversification occurred cyclically across multiple geologic cycles, rather than the currently accepted model of "divergence post-Pleistocene deglaciation". The Great Lakes were formed iteratively over several glacial cycles, like a cheese grater, as our geology colleagues say.