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Artificial selection- Modifying species by selecting desired traits and breeding them.
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Natural selection- A selection process that occurs in nature by environmental factors that
allows only certain organisms to reproduce and survive.
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Extinction- An irrevocable loss of a species.
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Strata (layers)- The relative ages of fossils are determined by the layer on which they are
found. The top layer of strata is the youngest.
A fossil record provides some of the strongest evidence of evolution because of the
sequence in which fossils appear within layers of rocks.
Radioactive dating is also used to determine a fossils age.
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Homologous structures- Features that have different functions but are structurally similar
because of common ancestry.
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Evolutionary trees show patterns of decent.
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Gene pool- the total collection of genes in a population at any one time.
Population- A group of individuals of the same species living in the same place at the same
time.
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New alleles originate by MUTATION, which is a change in nucleotide sequence of DNA.
Mutation and sexual reproduction give genetic variation, making evolution possible
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Types of Genetic Drift:
Bottleneck effect- A drastic reduction in population size and change in allele frequencies.
Founder effect- Difference in the gene pool of a small colony compared with the original
population.
Gene flow- where a population may gain or loose alleles when fertile individuals move into
or out of a population or when gametes are transferred between populations.
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Stabilizing direction- favors intermediate phenotypes
Directional selection- Shifts the overall makeup of the population by acting against
individuals at one of the phenotypic extremes.
Disruptive direction- Favors individuals at both extremes of a phenotypic range.
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Sexual Dimorphism- noticeable differences, not directly associated with reproduction or
survival.
Sexual selection- A form of natural selection in which individuals with certain
characteristics are more likely than other individuals to obtain mates.
Intrasexual selection- When some species secondary sex structures may be used to
compete with members of the same sex for a partner.
Intersexual selection- Individuals of one sex are choosy in selecting their mates.
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