BIO 117 EXAM 1
evolution - ANSWER a change in a population over time Natural selection - ANSWER the process by which populations change over time What is necessary for natural selection to occur? - ANSWER traits within a population vary -some individuals leave more offspring than others (fitness) Mechanisms of evolutionary change - ANSWER Natural selection, genetic drift, gene flow and mutation Fitness - ANSWER the ability of an individual to produce offspring relative to others of the same species 1 / 3
Types of selection - ANSWER directional, stabilizing and disruptive Directional selection - ANSWER the result after selection will be one extreme or the other stabilizing selection - ANSWER the result after selection will be a median phenotype disruptive selection - ANSWER the median has the lowest fitness and the two extremes have the highest (graph will look like camel humps) Genetic drift - ANSWER cause change randomly -can lead to an increase in the frequency of alleles that decrease fitness (meaning something that original would have been the higher fitness no longer is)
-two components: founder and bottleneck 2 / 3
Founder effect - ANSWER begin with a large varied population; then a random sampling of a few individuals leave and establish a new population -not all variation will be in new generation Bottleneck effect - ANSWER a large population; a few randomly start a new population; death eliminates the original population Gene flow - ANSWER immigration and emigration -frequencies will be vastly different that what they would have been Immigration - ANSWER new individuals entering a population emigration - ANSWER individuals leaving a population
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