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EVOLUTION & NATURAL SELECTION VOCABULARY • Evolution • Gradual change in the genetics of a species/population over time; how descendants differ from their ancestors. Types of Selection • Artificial Selection • Selection by humans for breeding of useful traits from the natural variation among different organisms, Ex. Dog Breeding Types of Selection • Natural Selection • Process by which individuals that are better suited to their environment survive and reproduce successfully How to Survive • Struggle for Existence • Competition among members of a species for food, living space, and the other necessities of life • Fitness • Ability of an organism to survive and reproduce in its environment • Adaptation • Inherited characteristic that increases an organism’s chance of survival Question: Do you think that there is a struggle for existence between humans? Example of natural selection, adaptations, fitness and the struggle for existence. Peppered Moth Peppered Moth Evolution 2:04 Ancestry • Descent with Modification • Principle that each living species has descended, with changes, from other species over time • Common Descent • Principle that all living things have a common ancestor NOVA Embryo Development: http://www.pbs.org/wgb h/nova/evolution/guessembryo.html (Interactive) Natural Selection - "Stated Clearly“ 9:18 Ancestry • Homologous Structures • Structures that have different mature forms in different organisms but develop from the same embryonic tissues; common ancestor • Analogous Structures • Structures that appear the same but do not develop because of similar ancestry; same selective pressures • Vestigial Organs • A structure or organ that is useless today but an ancestor used Variation • Gene Pool • Combined genetic information of all the members of a particular population • Relative Frequency • Number of times an allele occurs in a gene pool compared with the number of times other alleles occur Question: Who is represented in the gene pool? Selection • Genetic Drift • Random change in allele frequencies that occurs in small populations • Founder Effect • Loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population Founder Effect 2:55 • Genetic Equilibrium • Situation in which allele frequencies remain constant How do we get separate species? • Speciation • Formation of new species • Reproductive Isolation • Separation of a species or populations so that they cannot interbreed and produce fertile offspring • Behavioral Isolation • Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding. Ex. Albatross 1:04, Ex. Birds of Paradise 2:02 How do we get separate species? • Geographic Isolation • Form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water • Temporal Isolation • Form of reproductive isolation in which two populations reproduce at different times CC - Big History "Evolution“ 15:04 What Darwin Never Knew 1:54:08 start @ 2:17