Flashcards
Natural Selection and Speciation AQA
Cards in this deck (12)
- 1Define a speciesA group of organisms with similar characteristics that can produce fertile offspring
- 2Define gene poolAll the alleles of all the genes in a population
- 34 conditions under which Hardy-Weinberg principle applies1. No immigration or emigration
2. Large population
3. No mutation
4. No Selection - 43 sources of genetic variation1. Mutation
2. Meiosis
3. Random fertilisation of gametes - 53 selection pressures that result in differential survival1. Predation
2. Disease
3. Competition - 6What is Speciation?The evolution of a new species from an existing one
(When reproductive separation of two populations results in the accumulation of difference in their gene pools. New species arise when these genetic differences lead to an inability of members of the populations to interbreed and produce fertile offspring) - 7Name 2 types of Speciation1. Allopatric - geographical isolation
2. Sympatric - reproductive isolation - 8What is stabilising Selection?When both extreme phenotypes are selected against/ the mean is better adapted to the environment
- 9Directional selectionOne extreme phenotype is favoured, so the mean shifts towards that extreme
- 10Disruptive selectionSelection against the mean phenotypes. Extreme phenotypes are favoured (so produces two humps on the graph)
- 11Define evolutionA change in the allele frequencies in a population
- 12Genetic driftWhen a small range of genes are randomly favoured, so in small populations allele frequencies change because of random removal of alleles
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- Flashcards on Natural Selection and Speciation AQA, created by Alex de Leeuw on 18/10/2017.
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- Alex de Leeuw
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