What is Life History Theory?
Life history theory is the branch of evolutionary biology that attempts to understand patterns of investment in growth, reproduction, and survival across the life cycle. It is the theory that explains the major transitions that mark individual organisms’ life cycles from conception to death. The diversity of life reflects a tremendous diversity in life histories. Some organisms live very short lives and reproduce in large numbers. Others spread a modest amount of reproduction out over a long lifespan. Still others live an extraordinarily long time and still manage to reproduce in massive numbers. Why do organisms differ so much in traits such as age at maturity, age-specific fertility, life expectancy, or clutch size? Why would a biological entity ever voluntarily reduce its reproductive output and, presumably, its fitness? How do humans fit into this diversity?
The Idea
We will approach the study of life history theory from a slightly unusual perspective. Over the course of ten weeks, we will read ten classic papers in the development of the field. We will discuss the papers, their context, their key results, and extensions during class meetings. I will also augment the readings and discussions with notes and videos that cover the key technical results of the papers.
The Papers
- Coale (1957): Renewal Equation (notes)
- Cole (1954): Iteroparity and Cole’s Paradox (notes,
RCode) - Charnov & Schaffer (1973): Resolution of Cole’s Paradox (notes)
- Gadgil & Bossert (1970): Reproductive Effort (notes)
- Schaffer (1974): The Balance Between Juvenile and Adult Mortality (notes)
- Smith & Fretwell (1974): Optimal Clutch Size (notes)
- Hamilton (1966): The Moulding of Senescence by Natural Selection (notes,
RCode, Notes on Fitness Sensitivities) - Lewontin & Cohen (1969): Growth in Random Environments (notes)
- Tuljapurkar & Orzack (1980): Fitness in Random Environments (notes)
- Charnov (1991): Assembly Rules of Mammalian Life Histories (notes)
Supplementary Notes
- The Life-Cycle Graph
- Notes on Risk
- Some Very Preliminary Notes on Fitness Sets. These notes are very rough and quite incomplete and should be updated at some point (hopefully) soon.
- Some Notes on Making Theoretical Plots in R. This will be an evolving set notes that provides examples of making scientific figures in
R. - Notes on Fitness Sensitivities. Quick introduction to matrix population models and derivation of fitness sensitivities.
- “Overheads” from videos. All the doodles from the videos!