Speciation
Key ideas relating to speciation, how different species occur and some links to natural selection and variation causing allele frequency to change and create new species.
- Created by: Noshin Mahmud
- Created on: 08-11-12 20:24
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- Speciation: formation of new species
- Variation
- mutation
- point mutation: single gene is changed either by deletion, addition or inversion. e.g: Sickle celled anaemia
- Chromosomal Mutation: changes in whole genes. e.g Downs Syndrome
- Random fusion of gametes
- Chiasmata: breaking and crossing over of homologous pairs of chromosomes, produces chromosomes with a new mix of genes
- mutation
- Natural selection: causes species with advantageous alleles to successfully breed, survive and pass on these alleles, this changes the allele frequency= leads to EVOLUTION
- May happen due to selection pressure: changes in environment/conditions
- Disruptive Selection: middle values die out
- Directional Selection:: One extreme dies out
- Stabilising Selection: 2 opposite ends of extremes die out
- Less advantageous species die out
- May happen due to competition
- INTERSPECIFIC competition: arises between different species. e.g: food and shleter
- INTRASPECIFIC competition occurs between the same species: e.g:mating
- May happen due to selection pressure: changes in environment/conditions
- Reproductive Isolation: (for example due to behavioural patterns) leads to sympatric speciation
- Geographical Isolation: leads to allopatric speciation
- Variation
- Geographical Isolation: leads to allopatric speciation
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