Carl P Simon | Choice of Fitness Function Matters. Which One Do Salmon Use? | Nov. 10 2020

Carl P. Simon, Emeritus - UM Mathematics, Complex Systems and Ford School of Public Policy

Joint work with:
James Breck, Edward Rutherford, and Bobbi Low

Abstract: Life history theory focuses on characteristics of organisms, such as size and age at maturity or tradeoffs between egg number and egg size. It studies how such traits vary as evolutionary responses to natural selection that optimize fitness. One needs to know such characteristics to understand behavior and to design successful conservation strategies. A critical step in such studies is to have the right fitness function. Most theoretical ecologists concerned with life history traits work with one of the classic fitness functions: the intrinsic rate of natural increase r, the net reproductive number R₀, or Fisher’s reproductive value of a female of age x, Vₓ. Their choice among these three is sometimes driven by mathematical parsimony. Working with semelparous and iteroparous Great Lakes salmon, we find that different fitness functions can lead to very different adaptive behaviors to environmental changes. This observation sheds light on just which fitness function may be operational for a given species.