Date: Wednesday, April 6, 2022

Time: 8:15 AM CDT

Zoom link: Please click this URL to start or join. https://iastate.zoom.us/j/91558404255?pwd=TkhhbUNJN1hUSEJpTjAzbEtQbU5pUT09  

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Presenter: Audrey McCombs, PhD candidate in Statistics and Ecology & Evolutionary Biology

Title: Parametric models for ecological networks, and an integrated population model for sagebrush abundance in Yellowstone National Park

The first part of the talk will present a hierarchical Bayesian model for abundance of Artemesia tridentata (big sagebrush) in the Sagebrush Steppe ecosystem in Yellowstone National Park.  The model combines two datasets - percent cover data from the National Ecological Observatory Network (NEON), and cover class data from the National Park Service (NPS) monitoring program - by estimating a latent Beta distribution generating the observations.  The model accounts for repeated sampling and non-linear effects of spatial location on species abundance.  I identify conditions under which a combined model has better statistical properties than separate models for each dataset, and discover that in some cases it is better *not* to combine datasets into a single model.  The second part of the talk will switch gears to discuss statistical models for ecological networks.  I will discuss problems with the current non-parametric approach to statistical inference using null models, and present four parametric alternatives with examples from the ecological network literature.

Audrey McCombs is a non-traditional PhD candidate enrolled in the Ecology and Evolutionary Biology program, housed in the Statistics department, and co-majoring in ecology and statistics.  She is currently most interested in modeling ecological systems, theoretical ecology, and ecological networks, but has worked on a variety of projects as a statistical consultant and enjoys exploring diverse scientific questions and fields. Recent publications include work on COVID-19 vaccination strategies, changes in nectar resources for pollinators under climate change, and the relationship between fish abundance and catch per unit effort (CPUE) in Iowa lakes.  She holds an M.F.A. in creative writing and environment from Iowa State University, an M.A. in philosophy from Johns Hopkins University, and a B.A. in philosophy from UC Berkeley.