APES Chapter 4

Class Notes

• Evolution: changes in a population's genetic composition over time (millions of years)
• Gene pool: All of the genes present in a population and their frequencies
• Mutation: changes to alleles
• Alleles: alternative forms of a gene that give an organism its traits

^^Theories of Evolution:^^

• ^^Changes in inherited characteristics of populations over time^^
• ^^All organisms descended from a common ancestor^^
• ^^Mutations provide the raw material needed for evolution^^
• ^^Evolution can occur as a result of natural selection or do to random chance (genetic drift) Alleles mutate Organisms are selected (based on their alleles) Populations evolve^^
• Natural Selection: certain traits give organisms higher reproductive success → leads to spread of alleles
• Adaptations: traits that benefit a population in its environment
• Fossils: evidence of evolution
• Speciation: when two organisms can no longer produce viable offspring → two different species
• Reproductive isolation: what distinguishes one species from another; no viable offspring.
• Allopatric: most common speciation, occurs with geographic isolation
• sympatric: less common speciation with no geographical isolation, “spontaneous”

^^EVOLUTION OCCURS THROUGH GENETIC DRIFT AND NATURAL SELECTION^^

• Genetic drift: chance involved in alleles surviving or going extinct
• Derived Traits: something happened new (evolutionarily); do not appear in ancestral fossils
• Ancestral Traits: features that organisms share from common ancestors

Textbook Notes

• Artificial selection: selectively breeding different individuals based on traits, then continuing to choose the individuals that inherit the desired feature.
• genetic engineering: modifying genes of an organism by transferring segments of dna from one organism to another
• species diversity: A measure of the number and variety of species in an ecosystem
• Species evenness:  level of equality in the number of individuals per species
• Species richness: number of different species in a given area
• niche: role a species plays in an ecosystem, including how it interacts with other organisms and the resources it needs to survive.
• generalist: species that have broad niches with a variety of acceptable foods and climate conditions (ie rats, deer, humans)
• Specialist species: only suited to one habitat with a limited number of food sources → less adaptive
• Native species: species that normally live and flourish in a specific environment
• Nonnative species/invasive species: species that accidentally migrate or are brought by humans intentionally or unintentionally to a new environment
• Indicator species: are sensitive to changes or issues in an ecosystem, such as illness, pollution, parasitic infection, or other negative change (ie amphibians)
• Keystone species: species whose presence and role have a large effect on other populations in abundance and type (ie American Alligators)