Mathematical Biology Seminar

Stephen Proulx
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara

Playing dice with your children’s future vs. telling them what to do: population and evolutionary dynamics in fluctuating environments

Wednesday, April 19, 2017, at 3:05pm
LCB 219

How should parents act to improve the fitness of their offspring in an uncertain world? I will discuss three genetically encoded strategies that can be favored when the external environment follows a Markov process at the same time-scale as reproduction. A famous strategy is one where parents play dice with their offspring and randomize the offspring traits, a phenomena known as “diversifying bet-hedging”. Parents produce a range of offspring, some of which are destined to have low fitness regardless of the environmental conditions they face. Another is that some non-genetic process allows offspring to inherit some aspects of the parent’s phenotype, a process sometimes called phenotypic memory or epigenetic inheritance. A third possibility is that parents use their own wisdom to choose their offspring’s path in life, a process called trans-generational plasticity. Trans-generational plasticity relies on their being some correlation (positive or negative) between parental and offspring environments.

I will discuss our recent work that calculates the growth rate of populations using these different strategies and examines the rate of invasion of alternative, genetically encoded maternal effect strategies. Randomizing maternal effects tend to produce higher fitness than trans-generational plasticity when there is little covariance between successive environmental states. However, even when the environmental covariance is weak, we find that trans-generational plasticity always invades the ancestral population. This suggests that informative maternal effect strategies have evolved first and that bet-hedging strategies can only evolve afterwards.