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Chapter 3

PSYCH 1XX3 Chapter 3: Module 3- Evolution 1

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Joe Kim

Module 3- Evolution 1 Psych 1XX3 Adaptations Adaptation: biological traits that help an individual to survive and reproduce in its habitat. Always serve some function in life Higher mental Processes - Selective memory - Memory encoding - Memory retrieval Evolution by Natural Selection - Adaptation emerge in development as a result of relevant genes in interaction with the environment - Charles Darwin and Alfred Russel Wallace - One of the four basic mechanisms of evolution (other 3 listed below) o Genetic drift o Mutation o Migration - The process of natural selection can be descried as the differential survival and reproduction of organisms due to the heritable difference between them - For natural selection there must be three components o Heritability o Variation o Reproductive success Natural Selection in the Wild Stabilizing selection: selection against any sort of departure from the species- typical adaptive design - A classic example of rapid evolutionary change comes from the work on studying the evolution of beak size in a species called the Medium Ground- Finch which lives on Daphne Island in the Galapagos - In 1977 a severe drought hit the island and decimated the vegetation, food was scarce and all the small seeds were quickly eaten up leaving only the large ones - The birds with unusually heavy beaks were able to eat the hard seeds so they survived the drought - Between 1976-1978 the average beak depth 9.4 mm to 10.2 mm - The large beaks went on to reproduce Reproductive Success is Fitness - Natural selection is referred to as survival of the fittest - Fitness refers to the amount of children a person produces in other words the amount of genes they carry on to the next generation - Darwinian fitness: average reproductive success of a genotype relative to alternative genotypes - The fittest individual is not always the smartest, biggest or fastest - Fitness is ultimately about the competition between genotypes to leave copies of themselves in the next generation biologists like to define evolution as the change in allele frequencies over generations Sexual Selection - In sexually reproducing organisms there is often competition for mates and natural selection acts on mate-finding and reproductive behaviors, this is sexual selection - Peacocks o Sexual dimorphism o The male grows extravagant feathers in order to attract a mate o If the feathers impress the peahen then
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