BIOL108 Lecture 3: Topic 3.docx

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Richard Moses

Document Summary

Topic 3 evolution: natural selection, adaptation and speciation. Compiled evidence for descent with modification, or macroevolution: 2. Outline a mechanism for evolution called natural selection: darwin (and wallace) reasoned, observation 1: populations over-produce . Many individuals do not live to reproduce because there aren"t enough resources for all of the offspring. Therefore: resources are limited and individuals compete for access to them in a struggle for existence : observation 2: phenotypic variation exists in all groups of organisms. You can have a beneficial gene, but your environment can be unfavourable to you, and you can have a disadvantageous phenotype: thus the gene will not be able to benefit you. But only populations evolve: natural selection has no goal. Just because a mutation would help an organism, doesn"t mean it is going to happen because mutation is random. Does not anticipate need of a specific trait.