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Ch. 15 Evolution
Able/Brown flashcards
16
Biology
9th Grade
02/21/2008

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Term
Charles Darwin
Definition
The author of Origin of the Species, also the first person to observe the fact that organisms change over time due to random mutations
Term
Extinction
Definition
when all the population of a species dies out.
Term
Natural Selection
Definition
Organisms change due to random mutations and if these mutations improve their ability to live and reproduce, they will change and these changes will be pssed to their offspring. "Only the strong survive"
Term
Population genetics
Definition
the gene pool of all the genes in a species
Term
Mutations
Definition
Changes in genes caused by natural causes or environmental causes
Term
Stabilizing Selection
Definition
natural selection where the average individual is favored. This results in a decline in population variation
Term
Directional Selection
Definition
Natural selection that favors extremes in a population - a cause of major evolutionary change
Term
Disruptive Selection
Definition
Natural selection that favors either extreme of a trait, the average in the middle disappears.
Term
Homologous Structures
Definition
structures with common evolutionay origins
Term
Vestigial Structures
Definition
Stuctures on modern species that have no purpose anymore, but maybe once did.
Term
genetic drift
Definition
when allelic frequencies change due to historical events.
Term
gene flow
Definition
when an organism enters or leaves the gene pool
Term
Geographic isolation
Definition
when a species is isolated away from the rest of the population and the gene pool is very limited.
Term
Adaptive radiation
Definition
a type of divergent evolution in which an ancestralspecies evolves into many different species to fit a number of diverse habitat.
Term
Divergent evolution
Definition
evolution where similar species get more different because of the different environments that they live in.
Term
convergent evolution
Definition
evolution where different species become more alike over time due to environmental pressures.
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