Exam 1 Flashcards
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Define population genetics.
Genetic differences within and between populations.
Define allelic frequency.
Fraction of all chromosome frequencies in a population.
Define genotype frequency.
Number expressed as a percent of individuals with a specific genotype.
Define Phenotypic frequency.
Number expressed as a percent of individuals in a population who express a specific phenotype.
Define Hardy-Weinberg equilibrium.
Genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
Five agents of evolutionary change.
Genetic drift, non random mateing, mutation, gene flow, natural selection.
What is genetic mutation?
Random change in a gene making it different from the parent gene.
What is gene flow?
The movement of genetic material from one population to another.
What is non random mateing?
When the chances of mating with a specific trait are higher then others.
What is genetic drift?
in a small population gentic variation can disappear due to chance occurrences.
Define evolution.
Change in heritable characteristics of populations over successive generations.
Define natural selection.
Organisms best adapted to their environments tend to survive and transmit their genetic information.
What is Darwin’s theory?
All species and organisms arise from natural selection of an individual’s ability to survive and reproduce.
What is Lamarcks theory?
Physical changes in an organism can be transmitted to offspring
Criteria necessary for natural selection to occur.
1) genetic variation must exist
2) genetic variation much be heritable
3) organism must survive to pass genetics to offspring.
Define fitness.
Organisms ability to survive mate and produce offspring.
What is selection pressure?
External agents which affect an organisms ability to survive in a given environment.
3 Types of selection.
- Stabilizing Selection (section against extremes)
- Directional Selection (selection towards one extreme)
- Disruptive Selection (selection towards extremes)
Define artificial selection.
Intentional breeding of plants and animals for select traits.
Describe heterozygous advantage.
The case in which heterozygotes have a higher fitness then homozygotes.
Define sexual selection.
Selection which sexes acquire distinct forms.
Define intrasexual selection.
Members of the same sex compete for mates.
Define Intersexual selection.
Females choose mates.
Define convergent evolution.
Species developed the same traits due to being exposed to the same selective pressures but do not come from a common ancestor.
Define divergent evolution.
Species with a same common ancestor evolve differences resulting in a new species.
Define adaptive radiation.
Organisms diversify and change rapidly to fill open niches.
Describe the biological species concept.
Group of Organisms that are reproductively isolated from other groups of organisms
Describe the process of speciation.
When groups in a species become reproductively isolated from the rest of the group and become genetically different from the rest.