Evolutionary Trade-offs
While there are many factors that can affect allele proportions in a population, selection is thought to be among the most powerful. Selection effectively shapes the heritable physiology, morphology, and behaviors of populations through differential reproduction among individuals. Natural selection affects traits related to survival and producing offspring, while sexual selection specifically affects traits related to obtaining mates. Often traits that increase an individual’s access to mates, actually decreases their survival. One of the models in this section depicts this evolutionary trade-off.
Model 1 – Endler’s Guppies
This model simulates Endler’s 1980 classic experiment on the balance of sexual selection and natural selection. In guppies, females prefer to mate with males that have lots of spots, but those males are more easily seen by predators. You can manipulate strength of female preference and the number of predators.
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Model 2 – Industrial Melanism
This model simulates the classic example of natural selection on color patterns in peppered moths (Biston betularia). When air pollution is low, lichens cover the trees and the light moths are well camouflaged. When air pollution is high, the trees become dark and the light moths stand out. The simulation takes place just prior to the industrial revolution and proceeds through to modern day.