Browsing by Author "Wagenius, Stuart"
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Item Aster Models for Life History Analysis(School of Statistics, University of Minnesota, 2005-09-05) Geyer, Charles J; Wagenius, Stuart; Shaw, Ruth GWe present a new class of statistical models designed for life history analysis of plants and animals. They allow joint analysis of data on survival and reproduction over multiple years, allow for variables having different statistical distributions, and correctly account for the dependence of variables on earlier variables (for example, that a dead individual stays dead and cannot reproduce). We illustrate their utility with an analysis of data taken from an experimental study of Echinacea angustifolia sampled from remnant prairie populations in western Minnesota. Statistically, they are graphical models with some resemblance to generalized linear models and survival analysis. They have directed acyclic graphs with nodes having no more than one parent. The conditional distribution of each node given the parent is a one-parameter exponential family with the parent variable the sample size. The model may be heterogeneous, each node having a different exponential family. We show that the joint distribution is a flat exponential family and derive its canonical parameters, Fisher information, and other properties. These models are implemented in an R package "aster" available from CRAN.Item Aster Models for Life History Analysis(University of Minnesota, 2005-09) Geyer, Charles J.; Wagenius, Stuart; Shaw, Ruth G.Item More Supporting Data Analysis for "Unifying Life History Analysis for Inference of Fitness and Population Growth"(University of Minnesota, 2007-11) Geyer, Charles J.; Wagenius, Stuart; Shaw, Ruth G.; Hangelbroek, Helen H.; Etterson, Julie R.Item R Code and Data for: High juvenile mortality overwhelms benefits of mating potential for reproductive fitness(2022-04-29) Waananen, Amy; Richardson, Lea K; Thoen, Riley D; Nordstrom, Scott W; Eichenberger, Erin G; Kiefer, Gretel; Dykstra, Amy B; Shaw, Ruth G; Wagenius, Stuart; waana001@umn.edu; Waananen, AmyAn individual’s fitness depends not only on its fecundity, but also on the viability of its offspring. Plant ecologists typically equate fecundity, or seed yield, with reproductive fitness, but fecundity might not correspond to offspring survival. Furthermore, individual fecundity and survival of the offspring might respond differently to external factors affecting fitness. One factor that may influence reproductive fitness through effects on both fecundity and offspring survival is mating opportunity, e.g., an individual’s access to potential mates. We investigated the relationship between maternal mating opportunity and both fecundity and offspring survival in populations of a long-lived herbaceous perennial, Echinacea angustifolia. Across seven years and 14 sites, we quantified the mating opportunity of 1279 plants and followed the progeny from these mating bouts over eight subsequent years. We used aster models to evaluate the relationship between mating opportunity and both the number of seedlings emerging and the number of progeny alive after 8 years. Seedling emergence increased strongly with mating opportunity, but we did not detect a significant relationship between progeny count after eight years and mating opportunity. These results show that mating opportunity increases fecundity, but its benefit to overall fitness may be weak.Item Supporting Data Analysis for "Unifying Life History Analysis for Inference of Fitness and Population Growth"(University of Minnesota, 2007-07) Geyer, Charles J.; Wagenius, Stuart; Shaw, Ruth G.; Hangelbroek, Helen H.; Etterson, Julie R.Item Yet More Supporting Data Analysis for "Unifying Life History Analysis for Inference of Fitness and Population Growth"(University of Minnesota, 2008-01) Geyer, Charles J.; Wagenius, Stuart; Shaw, Ruth G.; Hangelbroek, Helen H.; Etterson, Julie R.