Unit 6- Teacher Notes
Population: A group of organisms of the same species living in a specific area
Species: An interbreeding population of organisms that can produce healthy, fertile offspring
Gene Frequency: The percentage of a population that shows a particular gene/ how frequently a gene occurs in
a population of organisms
Variation: differences between individual members of a population. (Physical, behavioral, biochemical, etc.)
 Variation occurs due to...
• Genetic Mutations
– Gene Mutations
– Chromosomal Mutations
• Genetic Recombination:
– Crossing Over
– Independent Assortment
– Fertilization
Adaptation: an inherited trait that increases an organism's chances of survival and reproduction in a
particular environment
***NOTE: An individual can respond to their environment (i.e. sweating when it’s hot). They CANNOT
adapt…A population can adapt to their environment
Natural Selection: conditions in nature determine what individuals survive and reproduce
• Resulting adaptations allow better survival in the organisms' natural environment
• In order for natural selection to occur:
1. There must be VARIATION in a population.
2. There is a change in the environment.
3. Those organisms suited to the environment (with favorable adaptations) survive.
4. Individuals who survive, reproduce, and pass on the favorable variation to their offspring. Over
time, the gene frequency of the population changes.
Evolution: the change in gene frequency of a population over time
Artificial Selection: humans decide what survives and reproduces
• Resulting adaptations serve the needs of humans
Speciation: The evolution of one or more species from an original ancestor species
• In order for speciation to occur:
1. A population must be isolated/separated
2. Natural selection occurs differently in the isolated populations
3. The populations can no longer interbreed (reproductive isolation) when reintroduced
***Review Nature of Science (Venn Diagram)
Theory: an explanation for many related observations based on extensive scientific and experimental evidence
in many conditions
Evolutionary Theory/Macroevolution: The theory that life originated from one common unicellular ancestor
and became diverse through natural selection and speciation