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Date of Award


Document Type

Dissertation-ISU Access Only

Degree Name

Doctor of Philosophy (PhD)


School of Biological Sciences

First Advisor

Ben M. Sadd

Second Advisor

Scott K. Sakaluk


Infection can cause hosts to alter allocation to key life history traits. Infected individuals are generally expected to increase investment in defense (e.g., immune function) and, owing to underlying trade-offs, investment in other traits (e.g., current reproduction) is expected to decrease. However, the terminal investment hypothesis proposes that decreased lifespan due to infection, and the associated reduction in the expectation for future offspring, will favor increased investment in current reproduction to maximize lifetime reproductive success. Although terminal investment has been demonstrated in a wide array of taxa, its occurrence is not ubiquitous. I propose that conflicting findings can be reconciled if we consider terminal investment as a dynamic strategy with its expression contingent on context. For example, any factor that influences an individual’s expectation for future offspring (e.g., age) beyond the specific threat potentially cuing terminal investment may alter an individual’s propensity to adopt the strategy. I present a series of studies that address terminal investment and explore its dynamic nature across several important contexts using male decorated crickets (Gryllodes sigillatus), a species particularly amenable for large-scale assessments of reproduction, and more broadly, life history strategies.


Imported from ProQuest Duffield_ilstu_0092E_11353.pdf


Page Count


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