evidence of evolution evolutionary theories lamarck developed two theories of evolution: law of use...
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LAMARCK
Developed two theories of evolution: Law of Use and Disuse: the more a
part is used, the stronger it becomes
Inheritance of Acquired Characteristics: theory stating that useful traits developed during a lifetime are passed on to offspring
WEISMAN
Disproved Lamarck’s theory that acquired traits could be inherited by cutting off the tails of mice then mating them
RESULT: offspring of tailless mice were always born with normal length tails
MALTHUS
Believed that human population increased geometrically (2, 4, 8, 16)
Food production increased arithmetically (1, 2, 3, 4)
RESULT: millions of people must die to keep a balance between the need/supply of food
DARWIN
Background Information: Traveled for five years aboard the
HMS Beagle Made significant discoveries by
studying finches on the Galapagos Islands
RESULT: noticed that species on island resembled mainland species, but had adapted to different regions
THEORY OF NATURAL SELECTION
Nature acts as a selecting agent of an organism’s traits
Organisms better adapted to the environment survive and reproduce more successfully than organisms that are not as well adapted
Overall theme: traits that help an organism survive in a changing environment are passed on to offspring
DARWIN’S MAIN IDEAS
Overproduction: a population generally produces more offspring than can survive in an environment
COMPETITION
Definition: there is a struggle between organisms for space, food, water, light, minerals, and other limited resources
VARIATION
Definition: members of a population show differences in traits that make certain individuals better adapted to survive
Types of variations—differences in size, structure, color, etc.
NATURAL SELECTION
Some variations are more helpful than others—there is a natural selection against organisms that cannot adapt
Organisms that cannot adapt die
SURVIVAL OF THE FITTEST
Applies to those individuals that have variations that enable them to live and reproduce
INHERITANCE OF VARIATIONS
Organisms with more helpful variations are more likely to survive and reproduce, passing on variations to offspring