CH 17.1
SC.912.L.15.15: Describe how mutation and genetic recombination increase genetic
variation.
An individual’s genotype together with environmental conditions produces its phenotype.
Natural selection acts directly on phenotype (an individual’s characteristics, not genes.
Better suited individuals produce more offspring & pass more copies of their genes to the next
generation.
Gene pool-all the genes (and their alleles) in a population.
Evolution involves a change in the frequency of alleles in a population over time.
Populations evolve, while natural selection operates on individual organisms.
Sources of Genetic Variation
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Mutations-300 mutations make us different from our parents.
Genetic Recombination -sexual reproduction (sperm & egg) & crossing-over in meiosis.
Lateral gene transfer-pass genes from 1 individual to another that is not their offspring.
Single gene trait vs. polygenic traits
CH 17.2
SC.912.L.15.14: Discuss mechanisms of evolutionary change other than natural selection such
as genetic drift and gene flow.
Beside natural selection, genetic drift & gene flow cause evolutionary change.
Genetic drift is a change in allele frequency because some individuals produce more
descendents than other individuals (changes gene pool).
Gene flow is a mechanism for evolution because as individuals move in or out
(immigration/emigration) of a population, the gene pool is changed (change equilibrium).
Ex. American families have 2.1 children (less than death rate). Effect?
Muslim families have 6.3 children per family. Effect?
CH 17.3 Process of Specialization
Speciation-formation of new species
Reproductive isolation
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Behavioral isolation-use different mating songs
Geographic isolation-separated by geographic barriers
Temporal isolation-reproduce at different times
Darwin’s Finches (p.496-7)
CH 17.4 Molecular Evolution???