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Natural Selection The survival of an organism depends on its ability to sense and respond to the external environment. In all environments, organisms with similar needs compete for the same resources. These two facts fuel the process of natural selection. Natural selection is a process by which organisms with traits well suited to an environment survive and reproduce at a greater rate than organisms less suited to that environment. Natural selection can occur in the following four steps: 1. Overproduction: A species produces more offspring than will survive to maturity. 2. Genetic Variation: The individuals within the species’ population are all genetically slightly different from each other. 3. Struggle to Survive: Individuals of the population must struggle to avoid predators and find food and shelter. 4. Selection: Individuals that are successful at surviving are able to reproduce and pass on their genes to their offspring. Natural selection results in the following six things at both a molecular level and a population level: I. Diversity: either the number of different characteristics present in a population or the number of different species in an area II. Adaptation: a characteristic that helps an organism survive in its environment by adapting to its surroundings III. Speciation: the process by which two populations of the same species become so different that they can no longer interbreed IV. Extinction: the process of a species dying out completely V. Phylogeny: the evolutionary development of a species. VI. Behavior: conduct that makes an organism more likely to survive long enough Natural Selection The survival of an organism depends on its ability to sense and respond to the external environment. In all environments, organisms with similar needs compete for the same resources. These two facts fuel the process of natural selection. Natural selection is a process by which organisms with traits well suited to an environment survive and reproduce at a greater rate than organisms less suited to that environment. Natural selection can occur in the following four steps: 1. Overproduction: A species produces more offspring than will survive to maturity. 2. Genetic Variation: The individuals within the species’ population are all genetically slightly different from each other. 3. Struggle to Survive: Individuals of the population must struggle to avoid predators and find food and shelter. 4. Selection: Individuals that are successful at surviving are able to reproduce and pass on their genes to their offspring. Natural selection results in the following six things at both a molecular level and a population level: I. Diversity: either the number of different characteristics present in a population or the number of different species in an area II. Adaptation: a characteristic that helps an organism survive in its environment by adapting to its surroundings III. Speciation: the process by which two populations of the same species become so different that they can no longer interbreed IV. Extinction: the process of a species dying out completely V. Phylogeny: the evolutionary development of a species. VI. Behavior: conduct that makes an organism more likely to survive long enough