selection and speciation simple
- Created by: Caitlin Rock
- Created on: 23-01-15 13:26
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- selection & speciation
- selection
- directional
- phenotypes change as environmental conditions change.
- some individuals, falling either left or right of the mean will possess a phenotype more suited to the new conditions
- phenotypes change as environmental conditions change.
- stabilising
- if environmental conditions remain the same then those with phenotypes closest to the mean are favoured.
- these individuals are more likely to pass on their alleles to the next generation
- some individuals, falling either left or right of the mean will possess a phenotype more suited to the new conditions
- Stabilising selection therefore tends to eliminate phenotypes at the extremes
- these individuals are more likely to pass on their alleles to the next generation
- if environmental conditions remain the same then those with phenotypes closest to the mean are favoured.
- directional
- Speciation
- The evolution of new species from existing species
- Geographical isolation
- a physical barrier prevents two populations from breeding with one another e.g. oceans, rivers, mountain ranges.
- Different environmental conditions on different sides of the physical barrier mean that populations begin to adapt
- The organisms that possess the phenotypes that are favourable to a particular environment are more likely to pass on their alleles
- as the phenotype of a population changes, this can create a new species
- i.e. the two original populations can no longer interbreed to produce fertile offspring
- as the phenotype of a population changes, this can create a new species
- The organisms that possess the phenotypes that are favourable to a particular environment are more likely to pass on their alleles
- Different environmental conditions on different sides of the physical barrier mean that populations begin to adapt
- a physical barrier prevents two populations from breeding with one another e.g. oceans, rivers, mountain ranges.
- Geographical isolation
- The evolution of new species from existing species
- selection
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