APES Chapter 4

Evolution

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

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"

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

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)