Susanna Bryceson has joined the Morgan Lab as a PhD candidate. She is studying the spread of Australia’s C4 grasslands from the mid-Miocene (about 12 mya) to the present.
In the Americas, Europe, Russia and Africa, the development of grassland biomes (ie, prairies and savannas) is thought to have gained traction during the low atmospheric CO2 conditions of the Miocene, enabling the dominance and co-evolution of C4 grass types alongside large herds of grazing ungulates, like deer and buffalo.
Little is understood about how C4 grasses arrived and spread in Australia, and how they affected Australia’s Gondwanan vegetation and fauna. This invasion was unique because of Australia’s long isolation and the absence of large co-evolved herbivores that controlled the fuel loads of grasslands elsewhere. Australia’s increasing aridification during the Pliocene created new niches which were inhospitable for much of the Gondwanan-evolved flora and fauna but well suited to C4 grasses, and the Pleistocene saw C4 grasses establish fire as a key driver of our ecology. Sue’s research is investigating what factors enabled C4 grasslands to spread and drive extinctions of fire-sensitive biota, what factors may be limiting them, and what the implications might be for future grassland management.