Evolution and Agents of Evolution. Chapters 2 and 17. Origin of Species. Special creation - each of the different kinds of organisms were created in their present form.
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Evolution and Agents of Evolution Chapters 2 and 17
Origin of Species • Special creation- each of the different kinds of organisms were created in their present form. • Inheritance of acquired characteristics- the modifications an organism acquires during its lifetime can be passed along to its offspring.
Observations by Darwin in the Galápagos • Two Important Observations 1) Plants and animals on the island were similar to those on the nearby mainland. 2) Phenotypic variation occured between organisms from island to island.
Species evolve from other species. He termed this "descent with modification" = Evolution The mechanism or driving force of evolution is = Natural Selection Darwin repeatedly emphasized two points in his book.
Darwin cited the following in support of Natural Selection: • Variation occurs in every group of plants and animals. • All organisms have the potential to over-reproduce. • Natural resources are limited. • Only the most adapted to the local environment survive and pass along traits to the next generation.
Darwin's own sketches of Galápagos finches.(1) Large ground finch Geospiza magnirostris(2) Medium ground finch Geospiza fortis(3) Small tree finch Camarhynchus parvulus(4) Warbler finch Certhidea olivacea
Agents of Evolution • Mutation • Migration • Genetic Drift • Nonrandom Mating • Selection
Nonrandom mating- individuals with certain genotypes mate with one another more commonly than would be expected on a random basis.
Natural Selection- the process by which individuals that are better adapted than others in meeting the challenges of their habitat produce more offspring. • Three Types of Natural Selection • Stabilizing • Disruptive • Directional