Chapter 6- Evolutionary History

LT1: I can clearly explain to others that the process of evolution depends on genetic variation.

1. Gene Pool- the collection of alleles from all individuals in a population.

2. Alleles- different forms of a particular gene

3. Gene Frequency- refers to how common an allele is in a population

4. Mutation- A random change in DNA sequence, which can introduce new alleles into a population and is the primary source of genetic variation.

5. Recombination- The process of exchanging genetic material between chromosomes during meiosis

6. Random Assortment- The random distribution of alleles from different genes to gametes.

LT2: Explain to others that evolution can occur through random processes.

1. Genetic Drift- the process where variation is lost because of random variation in mating, mortality, fecundity, inheritance.

2. Bottleneck effect- when a population’s size is severely reduced, resulting in a loss of genetic diversity.

3. Founder effect- when a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation.

LT3: Evolution can also occur through selection (nonrandom process)

1. Selection- the process where certain organisms are more likely to survive and reproduce than others

2. Stabilizing Selection- a natural selection process that favors average traits over extreme traits

3. Directional Selection- individuals with one extreme vision of a trait have a better chance of surviving and reproducing, causing the population to shift towards that extreme trait over time

4. Disruptive Selection- A natural selection process that favors organisms with extreme traits, rather than those with intermediate traits.

LT4: Microevolution operates at the population level

1. Microevolution- the evolution of populations

2. Artificial selection- humans decide which individuals will breed; breeding is done with a preconceived goal for the traits of the population

3. Industrial Melanism- industrial activities cause habitats to become darker due to population and as a result individuals possessing darker phenotype are favored by selection.

LT5: Macroevolution operates at the species level and higher levels of taxonomic organization

1. Macroevolution- evolution at higher levels of organization, including species, genera, families, orders, and phyla.

2. Speciation- the evolution of new species

   Allopatric speciation- the evolution of new species through the process of geographic isolation

   Sympatric speciation- the evolution of new species through the process of geographic isolation

Polupoidy- a species that contains three or more sets of chromosomes.