College of Science & Engineering
Twin Cities
Two of the major issues impacting Earth’s ecosystems today are rapid climate change caused in significant part by the human consumption of fossil fuels and biodiversity loss primarily affected by warming conditions and habitat reduction. These two factors are spurring ecological change dramatically, affecting mammalian communities across North America. In order to have a positive impact on the conservation of biodiversity, it will be imperative to understand how mammalian communities will migrate and reassemble in response to ecological change. These processes have occurred in past communities as well, and as such, the fossil record provides a unique lens through which scientists can analyze how species are impacted by ecological change to help predict community reactions to climate change in the present and future.
This research aims to quantify and analyze the changes in North American mammalian functional diversity over the last 20,000 years from the Last Glacial Maximum to the present in order to determine the functional dynamics of Pleistocene non-analog faunas. The project applies a suite of functional diversity indices to fossil occurrence data spanning the continental United States. Faunas are binned by radiocarbon age in multiple time bins, representing several warming and cooling events, including the modern day, late Holocene, Holocene Hypsithermal, early Holocene, Younger Dryas Stadial, Bølling-Allerød, late Glacial, and Last Glacial Maximum. In addition, the ecological data will include three categorical variables: body size, dietary preference, and locomotor mode. Ecological niche modeling (ENM) techniques will be employed to project past species ranges for time intervals or regions that are not well-sampled. Lastly, ENMs will also be used to predict future ranges of mammalian species given current forecasts of climate over the course of this century.
Because many fossil assemblages do not include all species that lived at a given place in the past, these researchers need to understand how the functional diversity indices change for modern assemblages when complete species lists are rariefied (i.e., sub-sampled). To do this, they are using species lists and ecological attributes in an equal area grid of >2,000 cells superimposed over the geographic ranges of all modern North American land mammals. The species list in each grid will be randomly sampled 1,000 times over at each decrement to the total species richness in the cell, and for each sub-sample 7 functional diversity indices will be calculated. Results for each grid cell and for all grid cells will allow the group to understand the influence of incomplete species sampling at fossil sites on the functional diversity indices and allow us to determine the degree to which any are insenstive to incomplete sampling. The computationally intensive nature of this work requires the use of the supercomputers.