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BIO CHP 17
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What is the smallest unit that evolves?
population
alleles
the variant forms in which genes exist
no more than 2 for a given gene
-one from the mother
-one from the father
Gene pool
The sum total of alleles in a given population
Basis of evolution is...
a change in the frequency of allels in a gene pool
Micro-evolution
a change of allele frequencies within a population over a relatively short period of time.
these changes in alleele frequencies can said to have evolved
What are the 5 agents of micro-evolution?
-mutation
-gene flow
-genetic drift
-sexual selection
-natural selection
Mutation
Permanent alteration in an organism's DNA
Some mutations are heritable, meaning they can be passed on from one generation to the next.
Gene flow
Movement of genes from one population to another
through migration: movement of individuals from one population into the territory of another
Genetic drift
chance alternation of allele frequencies in a population
has greatest effects on small populations
-bottleneck effect
-the founder effect
Sexual selection
form of natural selection that can affect the frequency of alleles in a gene pool
occurs when differences in reproductive success arise becuse of differential success in mating
Natural selection
Some individuals more successful than others in surviving
-and hence reproducing
-owing to traits that better adapt them to their environment
Evolutionary Fitness
the phrase "survival of the fittest" is misleading
-implies that evolution works to produce generally superior being who would be successful competitors in any environment
only has to do with relative reprouctive success of individuals in a given environment at a given time.
What are the three modes of natural selction?
Stabilizing, directional, diruptive
Stabilizing Selection
most common
moves a given character in a population toward intermediate forms and hence tends to preserve the status quo
Directional Selection
moves a given character toward one of its extreme forms
Disruptive Selection
moves a given character toward two extreme forms
(rarest form)
Author
blackkballoon
ID
71485
Card Set
BIO CHP 17
Description
Chapter 17 of the biology book that discusses micro-evolution
Updated
2011-03-08T03:44:13Z
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