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inherited characteristic that increases an organism's chance of survival

adaptive radiation

the development of many different forms from an originally homogeneous group of organisms as they fill different ecological niches


one of two alternate forms of a gene that can have the same locus on homologous chromosomes and are responsible for alternative traits

allopatric separation

when a geographical barrier physically isolates populations and blockes gene flow
ex: antelope squirrel on south of grand canyon are different species as those on the north side

analogous structure

structures that are not the same in form but are used for the same purpose ex: bird wing and fly wing

artificial selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

behavioral isolation

form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

bottle neck effect

natural disaster eliminates most of the population- members left contribute the alleles for the new pop.


Part of Horiz. Spp Concept, plugs into population genetics framework. Species are groups of interbreeding natural populations that are reproductively isolated. If individuals interbreed, allele frequencies stay similar within population. If no interbreeding, alleles between populations vary. Can Explain similarities within species. Concerned with isolating mechanisms like Pre/Post-zygotic barriers. Probs with BSC is concerning asexual organisms like bacteria, fossils and poorly known species where interbreeding cannot be tested, also incomplete isolation in ring spp or hybrid zones.


a system of biological taxonomy based on the quantitative analysis of comparative data and used to reconstruct cladograms summarizing the (assumed) phylogenetic relations and evolutionary history of groups of organisms


diagram that shows the evolutionary relationships among a group of organisms


the occurrence of two or more things coming together

convergent evolution

process by which unrelated organisms independently evolve similarities when adapting to similar environments

derived character

Characteristic that appears in recent parts of a lineage, but not in its older members


the act of moving away in different direction from a common point

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


sequence of DNA that codes for a protein and thus determines a trait

gene flow

exchange of genes between populations

gene pool

combined genetic information of all the members of a particular population

genetic drift

The gradual changes in gene frequencies in a population due to random events

genetic equilibrium

condition in which the frequency of alleles in a population remains the same over generations


genetic makeup of an organism

geographic isolation

Form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

hardy weinberg equilibrium

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


having two different alleles for a trait

homologous structures

Structures in different species that are similar because of common ancestry.

homozygous dominant

Both alleles (factors) for a trait are the same and dominant (AA)

homozygous recessive

Both alleles (factors) for a trait are the same and recessive (aa)

lamark vs darwin

LaMarck (1809)
Tendency toward perfection
Use and Disuse
Inherit acquired traits

Darwin (1859)
Heritable traits


said human population cannot continue to increase exponentially; consequences will be war, famine & disease

natural selection

a natural process resulting in the evolution of organisms best adapted to the environment

null hypothesis

hypothesis that states there is no difference between two or more sets of data making it opposite of the research hypothesis


Physical characteristics of an organism, determined by genotype

phylogenic tree

a branching diagram that shows how organisms are related through evolution


a group of organisms of the same species populating a given area

punctuated equilibrium

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

radiometric dating

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

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring


a change from one state to the opposite state

scientific name

the two-part, scientifically recognized name given to an organism, consisting of its genus and species. for some reason it is written in a dead language


a form of natural selection in which individuals with certain inherited characteristics are more likely to obtain mates


the formation of new species as a result of evolution

sympatric isolation

two subpopulations become reproductively isolated within the same geographic area


practice of classifying plants and animals according to their presumed natural relationships

timing isolation

a reproductive barrier; different animals go into heat at different times.


(biology) an organism that has characteristics resulting from chromosomal alteration

viable offspring

Offspring that can reproduce

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