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theses

Life history theory is concerned with understanding the timing of key events in organisms’ lives, such as growth, reproduction, and senescence. The evolution of these life history traits often involves trade-offs in the way that organisms allocate their resources. A major goal of life history theory is to understand the selective pressures governing these trade-offs and how they are shaped by organisms’ environments. Eusocial organisms, such as the European honeybee, are excellent model systems for exploring life history evolution because of their extraordinary phenotypic plasticity in many relevant life history traits. For organisms with these complex social structures, trade-offs over resource allocation occur at the level of the group rather than the individual. Since most individuals in a eusocial colony do not reproduce, their fitness depends on the success of the colony and selection on life history traits therefore acts mostly on the colony phenotype. Though there has been much theoretical work on life history evolution, there has thus far been no general framework for understanding the evolution of life history trade-offs in social organisms. To develop such a framework, I create a series of mathematical models that examine how a eusocial insect colony should optimally allocate energetic resources among survival, growth, and reproduction. I parameterize and test these models using honeybees as a model system and compare model predictions to observed traits in honeybees to gain insight into selective pressures shaping their life history. For my first chapter, I examine how seasonal environmental fluctuations influence the selective pressures on worker senescence in honeybee colonies. For my second chapter, I examine how the costs and benefits associated with worker longevity influence a honeybee colony’s optimal investment in worker somatic maintenance. For my third chapter, I explore how trade-offs over resource allocation and sexual selection interact to influence the optimal timing of reproductive investment in honeybee colonies. Together, these models contribute to our understanding of the selective pressures shaping resource allocation in social insect colonies and provide a quantitative framework for examining life history evolution in complex social systems.

ETD_8347

Ph.D.

Includes bibliographical references

by Natalie J. Lemanski

doi:10.7282/T3C250KQ

ETD doctoral

The author owns the copyright to this work.