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individuals do not evolve, these do


heritable change in line of descent


original source of new alleles

natural selection

can only occur in populations where there are selective pressures and differences in forms of heritable traits. survival of the fittest

stabilizing selection

eliminates uncommon forms of alleles, favors intermediates forms of a trait

Directional Selection

favors extreme forms of a trait

Disruptive Selection

favors extreme forms of traits, eliminates common forms of alleles

Sexual dimorphism

sexual selection, such as competition between males for access to fertile females, frequently influences aspects of body form leads to

Balanced polymorphism

persistence of the sickle allele at high frequency in a population

gene flow

tends to keep different populations of a species similar to one another, allele frequencies change owing to immigration, emigration or both

allopatric speciation

a fire devastates all trees in a wide swath of forest, populations of a tree dwelling frog on either side of the burned area diverge

genetic drift

change in a populations allele frequencies due to chance alone

adaptive radiation

burst of divergences from one lineage into a set of niches


leads to interdependent species

Homologous Structures

may differ in size shape and function in major groups of organisms, mutation may lead to major differences between adults of related lineages by altering steps in embryo development. human arm and bird wing

morphological divergence

a body part of an ancestor is modified differently in different lines of descent

amino acid sequence

some mutations are neutral because they don't affect...

mitochondrial dna

may be used in cladistic comparison of different species, individuals of the same species

molecular clocks

based on comparisons of the neutral mutations between species


based on character differences between species


in evolutionary trees each branch represents

Sister Groups

same age in cladograms


evolutionary history


sets within sets

homeotic genes

similar across diverse taxa

analogous structures

insect wing and bird wing

Big bang model

universe is continuing to expand


abundance of in atmosphere would have prevented the spontaneous assembly of organic cmpds

Stanley Miller

experiment illustrated that oxygen is necessary for life

Deep Sea vents

prevelance of iron sulfide cofactors in living organism that life may have arose near

protein formation

negatively charged clay particles played a role in


rna that acts as an enzyme

Heat from hydrothermal vents

certain pigments that evolved and were later used in photosynthesis may have originally helped cells detect..

noncyclic pathway

evolution of caused increase in oxygen levels

aerobic bacteria

mitochondria probably descendants of


one cells lives in another and becomes interdependent


dome shaped structure formed by mats of photosynthetic cells and sediments


first eukaryotes


dna or rna may be the genetic material of a


viroid consists entirely of, plasmid circle of

prokaryotic fission

how bacteriophages multiply


genetic material of hiv


bacteria transfer plasmids by


all are oxygen releasing phototrophs


ecoli cells that live in your gut are


all are intracellular parasites of vertebrates


formed by gram positive bacteria to survive harsh conditions


worldwide outbreak of a disease

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