Abstract: Historical biogeography, the study of the spatial distributions of organisms through geological and evolutionary time, offers a wealth of untapped ideas and approaches that can be adapted to microbial systems to better understand and predict their biology. This talk will focus on three intertwined vignettes of using a historical biogeography perspective to understand the present in microbial systems. First, it will discuss findings that the global distributions of many extant subsurface bacterial and archaeal taxa follow historic tectonic plate arrangements, particularly those from approximately 60 million years ago. These distributions may be the result of increased sedimentation at the Cretaceous–Paleogene boundary, which "locked" living microbes in the subsurface where they have persisted for millions of years. Second, it will discuss research showing that bacteria in soils across the Tibetan Plateau and North America show ubiquitous legacy effects -- that is, their geographic distributions lag up to fifty years behind existing climate change -- and using niche modeling that these legacy effects would entail sweeping shifts in diversity if bacterial distributions were to equilibrate to the contemporary climate. Third, it will describe findings showing that across almost all environments on Earth, microbial communities tend to be subsets of each other -- they are nested -- a pattern that may result from microbial niche specialization and diversification evolving in universal sequences of events across lineages. Taken together, these findings demonstrate the power of applying historical perspectives to microbial systems, and they have ramifications for our understanding of the processes generating microbial biodiversity patterns and forecasting the likely impacts of climate change on agriculture and public health.
Speaker
Joshua Ladau