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bio quiz evolution

Terms in this set (56)

speciation
The process by which a new species evolves from a prior species, the most basic process in macroevolution.
microevolution
evolution on the smallest scale—a generation-to-generation change in the frequencies of alleles within a population
macroevolution
evolution on a large scale extending over geologic era and resulting in the formation of new taxonomic groups
biological species concept
a species concept defining a species as a population or group thereof whose members potentially interbreed and produce fertile offspring
species
group of similar organisms that can breed and produce fertile offspring
reproductive isolation
condition in which a reproductive barrier keeps two species from interbreeding
hybrids
offspring of crosses between parents with different traits
Prezygotic barriers
prevent mating or fertilization between species
Postzygotic barriers
Any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults.
morphological species concept
characterizes a species by body shape and other structural features
ecological species concept
defines a species as a set of organisms that are adapted to a particular set of resources
phylogenetic species concept
defines a species as a set of organisms with a unique genetic history
allopatric speciation
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.
sympatric speciation
The formation of new species in populations that live in the same geographic area
polyploidy
condition in which an organism has an extra set of chromosomes
allopolyploidy
polyploidy resulting from contribution of chromosomes from two or more species
autopolyploidy
The state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number
reinforcement
process by which natural selection increases reproductive isolation
hybrid zone
a geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
directional selection
(changing environment) occurs when conditions favor individuals exhibiting one extreme of a phenotypic range, thereby shifting a population's frequency curve for the phenotypic character in one direction or the other
stabilizing selection
- acts against both extreme phenotypes and favors intermediate variants. This mode of selection reduces variation and tends to maintain the status quo for a particular phenotypic character.
diversifying selection / disruptive
occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes
genealogical species concept
basal group of organisms whose members are all more closely related to each other than they are to any organisms outside the group ("exclusivity"), and which contains no exclusive group within it.
taxonomy
named species in hierarchy (increase complexity)
temporal isolation
different times of day, seasons, years, cannot mix gametes.
habitat isolation
same area, not same habitat. Physical barrier. Reproduce in water, vs land.
behavioral isolation
calls, rituals,
mechanical isolation
morphologic difference. left handed shell vs right handed, insects,
gametic isolation
sperm may not be able to fertilize eggs of another species.
hybrid inviability
genes of different parent species interact and impair.
hybrid sterility / fertility
-mule: hybrids are vigorous, but sterile
hybrid breakdown
1st gen hybrids = fertile, next gen = feeble/ sterile.
adaptive radiation
the diversification of a group of organisms into forms filling different ecological niches.
ring species
species that contain populations that are reproductively isolated from each other but can exchange genetic material through other, linking populations
gradualist model
Slow changes in species overtime. (long)
punctuated equilibrium
pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
gene pool
Combined genetic information of all the members of a particular population
population
A group of individuals that belong to the same species and live in the same area - produce fertile offspring - smallest unit of evolution
immigration
Movement of individuals into an area occupied by an existing population
emigration
Leaving a population
allele frequency
Number of times that an allele occurs in a gene pool compared with the number of alleles in that pool for the same gene
genotype frequency
The proportion of a genotype among individuals in a population
hardy weinberg equilibrium
theory of a stable, nonevolving population in which frequency of alleles do not change; only occurs in large, isolated populations with random mating, and no natural selection or mutations
hardy weinberg equilibrium criteria
1 - very large pop
2- no gene flow between populations
3-no mutations
4- random mating
5- no natural selection
AGENTS OF CHANGE
AGENTS OF CHANGE
genetic drift
random events: change in freq of a gene variant, random sampling
bottleneck effect
: leads to loss of genetic diversity w/ small pop
founder effect
:few individuals colonize new habitat. Smaller group= different than parents
gene flow
exchange of alleles between mating populations of a species
mutation
: rare and random, have little effect on gene pool
non-random mating
mating that isn't random (limits the frequency of the expression of certain alleles)
natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

results in adaptive change when it upsets genetic equilibrium
diploidy
masks defective allele
(PRESERVING variation in populations)
balancing selection
maintain stable freqency: 2+ phenotypes
(PRESERVING variation in populations)
heterozygous advantage
greater reproductive success than homozygous
(PRESERVING variation in populations)
Freq dependent selection resulting from polymorphisms
2 different phenotypes r maintained in population
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