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change in a kind of organism over time; process by which modern organisms have descended from ancient organisms


inherited characteristic that increases an organism's chance of survival

descent with modification

process by which descendants of ancestral organisms spread into various habitats and accumulate adaptations to diverse ways of life

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival of the fittest


preserved remains or evidence of an ancient organism

fossil record

information about past life, including the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived


no longer existing

homologous structures

similar structures that related species have inherited from a common ancestor

vestigial structures

remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.


group of individuals of the same species that live in the same area


Differences between members of the same species.

artificial selection

selective breeding of domesticated plants and animals to produce offspring with desired genetic traits

gene pool

combined genetic information of all the members of a particular population


evolution on the smallest scale—a generation-to-generation change in the frequencies of alleles within a population

hardy-weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

genetic drift

random change in allele frequencies that occurs in small populations

gene flow

exchange of genes between populations


ability of an organism to survive and reproduce in its environment

biological species concept

definition of a species as a population or group of populations whose members can breed with one another in nature and produce fertile offspring


large-scale evolutionary changes that take place over long periods of time


formation of new species

reproductive isolation

condition in which a reproductive barrier keeps two species from interbreeding

geographic isolation

separation of populations as a result of geographic change or migration to geographically isolated places

adaptive radiation

evolution from a common ancestor of many species adapted to diverse environments

punctuated equilibrium

pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change


study of multicellular organisms as they develop from fertilized eggs to fully formed organisms

geologic time scale

scale used by paleontologists to represent evolutionary time

radiometric dating

the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products


the period of time in which half of a radioactive substance decays

continental drift

the hypothesis that the continents slowly move across Earth's surface

mass extinction

When many types of living things become extinct at the same time.

darwin's two main points

Descent with modification and Natural Selection

evidence of change

1.homologous structures
2. vestigial structures
3. embryos have similar stages of development
4. molecular biology


modified for new use

pesticide resistance

1. natural selection screens traits available
2. natural selection favors traits that fit current environment

changes in the gene pool

1. natural selection
2. genetic drift

the bottle neck effect

When a population is srunk by external factors causing sudden species change.

founder effect

when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool isn't reflective of the source population

reproductive barriers between species

1. timing (different breeding seasons)
2. behavior
3. habitat
4. reproductive structures are incompatible
5. offspring can be infertile

geographic isolation and speciation

1. populations are separated
2. changes in the gene pool occur
3. genetic differences evolve
4. the two populations can no longer interbreed


a model of evolution in which gradual change over a long period of time leads to biological diversity

refinement of existing adaptations

complex structures can evolve from simpler structures having the same basic function
Ex: complex eye

adaptations of existing structures to new functions

example: penguin wings have been modified for swimming

relative dating

method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock

absolute dating

A technique used to determine the actual age of a fossil


the science of describing, naming, and classifying organisms

linnaean system

Kingdom, Phylum, Class, Order, Family, Genus, Species

divergent evolution

when two or more species sharing a common ancestor become more different over time

convergent evolution

the process by which unrelated species become more similar as they adapt to the same kind of environment

analogous structures

structures that do not have a common evolutionary origin but are similar in function


distinctive branches in history of life

6 kingdom system

Animalia, Plantae, Fungi, Protista, archaebacteria, Eubacteria

three domain system

A system of taxonomic classification based on three basic groups: Bacteria, Archaea, and Eukarya


absence of external ears; theory of bone and tissue (fat) conduction

how dolphins produce sounds

1. echolocation
2. releasing air through blowhole


large part of the brain that controls the senses and thinking


the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance

medulla oblongata (brain stem)

the part of the brain that controls involuntary actions, like breathing

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