Evolution Guide 4
How does the "modern synthesis" theory of evolution differ from Darwin's Theory of Natural Selection?
Darwin's theory of natural selection said that only natural selection caused evolution. Modern synthesis includes genetic factors, like genetic drift and genetic mutation, as factors of evolution.
Compare the effects of disruptive, directional and stabilizing selection on the genetic makeup of a population.
Disruptive selection is against the mean and towards both extremes. Directional selection is towards on extreme. Stabilizing selection is towards the mean and against extremes. Disruptive and Directional completely change the look of the population while Stabilizing just stabilizes the population so that the mean feature is most common.
Why do traits have to be heritable for evolution to affect them?
For evolution to occur the traits that survive have to be passed down to the next generation for the population to change. This means that the traits being passed down have to be able to be inherited by the offspring's.
Why is evolution an emergent property of populations of organisms? Why are individuals unable to evolve?
Individuals cannot evolve on their own. They can only evolve through reproduction and natural selection which happens over time.
Explain each of the following modes of evolution in a population. For each one, describe the cause of change in the genetic makeup of a population and how the population evolves as a result of that change, and provide 1 "real world" examples of the process in action: a. Natural Selection b. Genetic Drift c. Gene Flow d. Sexual Selection
Natural Selection are traits that improve survival or reproduction in the population. A change might be the change of beak shape to better accommodate the food supply available. The population evolves due to survival of the best fit and the species that survive pass on their trait which causes the population to evolve. Genetic Drift is a change in the frequency of trait in a population due to chance events. With the populations being smaller there is a higher chance for all of the population to change. Gene Flow is a change in the frequency of traits in a population due to immigration and emigration. Due to it only changing because of immigration and emigration it equalizes the change. Sexual Selection is a change in the frequency of traits in a population due to gender preferences. One female might prefer a certain feature of a male and because of that she will mate with that male which causes his genes to be passed on.
Why does evolution have to involve the change of the genetic makeup of a population over time?
Without the genetic makeup changing there is no way for populations to change and evolve their genes.