Population Evolution Flashcards
What are the two sources of variation in individuals?
- Genetic variation
- Phenotypic plasticity
What is an allele?
alternative versions of a gene that may produce distinguishable phenotypic effects.
What is a gene?
a discrete unit of hereditary information consisting of a specific nucleotide sequence of DNA.
How is genetic information shuffled during reproduction?
i) Crossing-over
ii) Independent assortment of chromosomes
iii) Random fertilization
What is phenotypic plasticity?
The capacity for marked variation in the phenotype as a result of environmental influences on the genotype during development .
What is a phenotype?
The observable physical and physiological traits of an organism.
What is a genotype?
The genetic code of an organism.
What can we use to model allele frequencies?
Hardy-Weinberg equilibrium
Hardy-Weinberg equilibrium states that:
The frequency of alleles in a population
will not change from generation to generation.
Assumptions of Hardy-Weinberg equilibrium:
1) No mutation
2) No genetic drift (Large population size)
3) No migration (No gene flow)
4) No sexual selection (Random mating)
5) No natural selection
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Why is Hardy-Weinberg equilibrium important?
1) It allows us to quantify the magnitude and direction of changes in allele frequencies.
2) It provides a starting point for understanding why changes are occurring.
Genetic variation may be maintained if:
1) No advantage
2) Selective environmental forces that favor
3) Those fluctuate
4) Heterozygotes have superior fitness.
5) There is frequency-dependent selection.
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The process of evolutionary modification (i.e. changes in allele frequencies and the resulting phenotypes) due to natural selection leads to:
Adaptation.
Selection can only act on:
Existing variation.
Evolution is limited by:
Historical constraints.
