WK 8 - Comparing Populations to Investigate How Vital Rates Drive Population Dynamics: An Exact Method for Calculating Life Table Response Experiments and an R Package That Does It for You

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Session Description: Life Table Response Experiments (LTREs) are a valuable and commonly used tool for comparative studies of population dynamics. An LTRE, usually performed on a set of matrix population models, decomposes the difference or variance in population growth rate into the contributions from the vital rates (e.g., survival, fertility). LTRE analyses have been used to inform conservation and management decisions, by providing information about which life history stages or processes have contributed most to differences in population growth rate between different situations (for example, an undisturbed seabird population compared with one near a human settlement). LTRE methods were developed and popularized several decades ago by Hal Caswell and colleagues. When these methods were first introduced, approximate calculations were necessary due to constraints in computing power. Based on the fANOVA framework introduced by Ellner et al. (2019, Ecology Letters), we have now developed methods to perform exact LTRE analyses. These methods improve upon the approximate methods through exact quantification of first- and second-order terms, and by quantifying interactions among multiple vital rates up to any desired order. This interactive workshop will serve as an introduction to the exact LTRE method and the R package that we've written, which is available online at https://github.com/chrissy3815/exactLTRE. To fully participate, attendees should have R or RStudio installed on their computer, and have some familiarity with using R. We will guide attendees through installing our R package.