BIOL 1050 Lecture 23 Outline of Last LectureI. BiogeographyII. Homologya. Molecular biologyb. Embryologyc. Anatomyd. Convergent evolutionIII. Mechanisms of evolution Outline of Current LectureI. Mechanisms of Evolutiona. Natural selection Current LectureI. Mechanisms of Evolutiona. Natural Selection i. Only natural selection generally improves an organisms ability to reproduce(variation for a trait)ii. Only natural selection generally leads to an increase in favorable traits (adaptations) in a population over many generations (heritability) iii. 3 conditions are necessary for natural selection to occur1. Must be variation for that trait within a population2. Offspring must inherit that trait from their parentsa. The transmission of traits from parents to their children through genetic information 3. Individuals with one version of the trait must produce more offspring than those with a different version of the trait (differential reproductive success)a. More organisms are born than can surviveb. Organisms struggle for existencec. Some organisms are more likely to survive and reproducei. Individuals with the trait most beneficial for reproducing in their environment generally leave more offspring than individuals with other traitsii. Over time, the alleles for those beneficial traits will increase in frequency in a population These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iv. The local environment determines what traits are favorablev. Natural selection does NOT lead to perfect organisms1. Environments change2. Mutations creating a perfect version of a gene may not occurvi. The environment selects what is favorable (not the individual or population)vii. Traits do not evolve because of needviii. Evolution is not deliberateix. Survival of the fittest?1. Being strongest, fastest, biggest, etc. does not mean an individual will be favored unless it improves reproductive abilityx. Fitness1. The relative amount of reproduction of an individual with a particular phenotype, compared with the reproductive output of individuals with alternative phenotypesxi. Artificial selection1. The selective breeding of domesticated plants and animals by humans2. Humans replace role of the environmentxii. Natural selection can cause the evolution of complex
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