biological evolution

The Greenfin darter, N. chlorobranchius. Photo by Isaac Szabo
A model of dispersal, speciation and extinction on a river network
Landscape evolution and biological evolution

The idea that landscapes are constantly changing is surprising on its own, but an additional surprise is that landscape evolution – changes in topography through time – may have measurable effects on biological evolution and biodiversity. For example, if you’re a fish and the watershed you live in is shrinking, that could make it more likely that your species will go extinct. On the other hand, if your habitat is expanding, that could allow new species to form. If watersheds merge or split, that can mix or separate the fish species that live in them. Some scientists have speculated that changes in the physical landscape, such as river captures (abrupt rerouting of one river into another), might have produced high biodiversity in some regions of the world.

Maya Stokes investigated this hypothesized mechanism by building a coupled model of landscape evolution and aquatic species dispersal, speciation, and extinction. She found that river basin reorganization can elevate diversification rates in ways that should be detectable in the phylogenetic record. Stokes is now collaborating with Tom Near (Yale) and Sean Gallen (Colorado State) to investigate connections between landscapes and speciation among the incredibly diverse freshwater fauna of the southern Appalachians.

  • Stokes, M.F. and J.T. Perron (2020). Modeling the evolution of aquatic organisms in dynamic river basins. J. Geophys. Res., 125, e2020JF005652.
Trace fossils of early animals, or traces of microbial mats and wave action?

In a very different area of intersection between biological evolution and geomorphology, Giulio Mariotti worked with the Perron group and Prof. Tanja Bosak’s lab to investigate the sedimentary record of early life on Earth through a combination of theory and laboratory experiments. One of his intriguing discoveries was that fragments of microbial mats interacting with wave-driven oscillatory flows can generate sedimentary features that had previously been interpreted as tracks left by early animals.

  • Mariotti, G., S. Pruss, X. Ai, J.T. Perron and T. Bosak (2016). Microbial origin of early animal trace fossils? J. Sedimentary Research, 86, 287–293,
  • Mariotti, G., S. Pruss, J.T. Perron and T. Bosak (2014), Microbial shaping of sedimentary wrinkle structures, Nature Geoscience, 7, 736–740,
  • Mariotti, G., J.T. Perron and T. Bosak (2014), Feedbacks between flow, sediment motion and microbial growth on sand bars initiate and shape elongated stromatolite mounds. EPSL, 397, 93-100,