- Natural populations have great reproductive potential
- But numbers remain about constant as many offspring fail to survive
- Due to environmental factors, competition for resources, predators, other selection pressures, that impose a limit on their number and organisms struggle to survive
- Individuals within a population show variation for natural selection to act on
- Variants with a selective advantage/which are best adapted to their environment are more likely to survive and reproduce
- Producing viable fertile offspring which pass on their favourite traits, thus favourable genotypes accumulate over time, leading to increased allele frequencies of favourable alleles
- Over many generations, evolutionary changes by natural selection and may form new species if reproductive isolation occurs which is necessary for speciation
- Include examples which may include: Darwin's finches, giraffes and how they got their long necks, peppered moths
Note: don't neglect points 1-4!
Reproductive isolation is key to explaining speciation
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