BayCEER Workshop 2023

Traits to Live or Traits to Die? – Tracing the Development of Functional Diversity in Trees During Cenozoic Climate Change

The native tree flora of northwest Europe today represents the aftermath of a series of climate-induced extinction events spanning the Cenozoic era (66 Ma – present). The evolutionary pressures have varied both in tempo and in nature, from long-term cooling that began in the Middle Eocene, to accelerated cooling during the Plio-Pleistocene transition, which then culminated in repeated glacial cycles over the Pleistocene. The modern challenge of deciding how European forests should be managed with future conditions in mind demands an understanding of how trees have responded to different climatic changes in the past. The purpose of this study is to investigate trends in the evolution of genus-level diversity in trees over course of the Cenozoic. Namely, I test the hypothesis that the selective processes by which some genera persisted, while others perished, were not random, but driven by favorable or unfavorable traits. I explore changes in trait values associated with different climatic changes. I show that the evolutionary outcomes of genera can be predicted with high accuracy using traits alone amid climatic changes of rapid tempo (over hundreds of thousands of years), such as during and after the Plio-Pleistocene transition, but not over long-term cooling that spanned tens of millions of years. Traits such as photosynthetic rate, lifespan, leaf density, stem specific density, and height were found to be highly correlated with modelled probability of survival.