Antonio Luo ApBio 4/23/07 A) The nonconstancy of species indicates that individuals are unique. Every individual within a species is genetically different. Every individual's DNA has unique variations. These variations usually show up in the phenotype. No two individuals in a species are alike. For example, half a millimeter's difference in the size of the beak of a finch means the difference between life and death under certain conditions. Branching evolution implies that we all came from one ancestor. The various breeds of dogs all share common ancestry, being all descended from wolves, but were domesticated by humans and then selectively bred in order to enhance various features such as coat color and length or body size. Gradual changes in species happen slowly and over a considerable period of time. When genes mutate, selection occurs, and populations evolve. Because the leaves on the trees that giraffes eat have grown taller and taller over time, so have giraffe’s neck. Natural selection
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This note was uploaded on 09/10/2009 for the course A 503 taught by Professor Henry during the Spring '09 term at Berkeley.