Implications of context-dependent scatterhoarding for seed survival and dispersal in North American oaks (Quercus)
Abstract
Scatterhoarding animals play a key role in the dispersal and reproduction of commercially and ecologically important tree species throughout the world. In particular, seed caching by animals such as tree squirrels (Sciurus ) and jays (Corvidae) is largely responsible for natural regeneration in eastern North American oaks (Quercus). In this dissertation, I explore the roles of seed traits, animal traits, and ecological context in determining how animals handle seeds, and how these handling decisions affect seed fate. I also develop new statistical approaches to the analysis of seed tracking data. Chapter 1 introduces the issue of context-dependent acorn dispersal from both a theoretical and applied perspective. Chapter 2 synthesizes the literature on scatterhoarding behavior under a utility-based choice modeling framework to develop a general model of hoarder decision-making. Chapters 3 and 4, respectively, use expectation-maximization (EM) techniques to derive an estimator for dispersal and survival of marked seeds with imperfect detection, and then apply this estimator to determine the effects of change in seed community composition on seed fate in northern red oak ( Q. rubra), white oak (Q. alba), and American chestnut (Castanea dentata) dispersed by forest rodents. Chapter 5 uses data on radio tagged northern pin oak (Q. palustris), black oak (Q. velutina), and white oak dispersed by blue jays (Cyanocitta cristata), tufted titmice (Baeolophus bicolor) and other birds to examine the effects of habitat on seed movement and survival. Finally, Chapter 6 proposes a hidden Markov model designed to analyze spatially explicit multistate mark-recapture data on tagged seeds.
Degree
Ph.D.
Advisors
Swihart, Purdue University.
Subject Area
Biostatistics|Ecology|Behavioral Sciences
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