BI111 Study Guide - Allele Frequency, Microevolution, Phenotype

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Published on 20 Apr 2013
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Chapter 16 13-03-03 1:59 PM
Microevolution: Small-scale genetic changes within populations, often in
response to shifting environmental circumstances or change events.
Population: all individuals of a single species that live together in the same
place and time.
Polymorphism: the existence of discrete variants of a character among
individuals of a population.
Gene Pool: the sum of all alleles at all gene loci (spot on the chromosome)
in all individuals in a population.
Genotype frequencies: the percentage of individuals in a population
possessing a particular genotype.
Phenotype frequencies: the percentage of individuals in a population
possessing a particular phenotype.
Allele frequencies: the abundance of one allele relative to others at the
same gene locus in individuals of a population.
Diploid: an organism or cell with two copies of each type of chromosome in
its nucleus.
Haploid: “” one copy of each…
Null Model: a conceptual model that predicts what one would see if a
particular factor had no effect.
Genetic equilibrium
Neutral mutations: are neither harmful nor helpful; may alter an
organism’s phenotype without influencing the reproduction or survival. (may
affect the organism later on if the environment changes)
Deleterious mutations alter an individual’s structure, function, or behavior in
harmful ways. (syndromes, weak bones)
Lethal mutations cause death.
If lethal allele is dominant, AA and Aa are both affected; if recessive only aa
is harmed.
If the individual passes before they reproduce, the allele is eliminated from
the gene pool.
Advantageous mutation produces a benefit for the individual, and the trait
may be preserved by natural selection.
Gene flow: the transfer of genes from one population to another through he
movement of individuals or their gametes (plants).
Genetic Drift: random fluctuations in the allele frequencies as a result of
chance events: usually reduces genetic variation.
Natural selection: the evolutionary process by which alleles that increase
the likelihood of survival and reproductive output of the individuals that
carry them become more common in subsequent generations.
Sexual Selection: males get flashy structures to attract females.
Sexual dimorphism: differences in the size or appearance of males or
females.
Inbreeding: a special form of nonrandom breeding in which genetically
related individuals mate with each other.
Balanced polymorphism: the maintenance of two or more phenotypes in
fairly stable proportion over many generations.
Frequency-dependent selection: a form of natural selection in which rare
phenotypes have a selective advantage simply because they are rare.
Neutral variation hypothesis: an evolutionary hypothesis that some
variation at gene loci coding for enzymes and other soluble proteins is
neither favoured nor eliminated by natural selection.

Document Summary

Microevolution: small-scale genetic changes within populations, often in response to shifting environmental circumstances or change events. Population: all individuals of a single species that live together in the same place and time. Polymorphism: the existence of discrete variants of a character among individuals of a population. Gene pool: the sum of all alleles at all gene loci (spot on the chromosome) in all individuals in a population. Genotype frequencies: the percentage of individuals in a population possessing a particular genotype. Phenotype frequencies: the percentage of individuals in a population possessing a particular phenotype. Allele frequencies: the abundance of one allele relative to others at the same gene locus in individuals of a population. Diploid: an organism or cell with two copies of each type of chromosome in its nucleus. Null model: a conceptual model that predicts what one would see if a particular factor had no effect.