| What is a Mutation | A random and permanent change to the DNA of an organism |
| What are 2 mutagenic agents | Radiation - x-rays and UV lights
Chemicals - mustard gas and caffeine |
| Why is variation important | To allow the population to evolve over time in response to changing environmental conditions |
| What are Adaptations | They increase their chances of survival and reproduction |
| What are the 3 Adaptations | Structural - what the organism looks like
Physiological - how the organism works
Behavioural - what the organism does |
| What is Natural selection | When species produce more offspring than the environment can handle. It occurs when there are selection pressures (survival of the fittest) |
| What is the result in Natural selection | The best adapted individuals survive to reproduce and pass on the best allele that give them a selective advantage |
| What are the 4 stages of Natural Selection | 1 - There is variation in the population
2 - The environment cannot support an unlimited population, so the individuals who are less well adapted die and do not reproduce
3 - The best adapted individuals reproduce producing individuals with similar genetic traits
4 - The most advantageous traits become more common in the population |
| what are the 3 reasons why the population become isolated | Geographic - sea, river, mountain, desert
Behavioural - different breeding time, different mating display
Ecological - areas have different temperatures, water availability, pH |
| What are the 4 stages of Speciation | 1 - Isolation - Geographic, Behavioural, Ecological
2 - Mutations - occur in both populations, mutations are needed to create new alleles in each of the populations
3 - Natural Selection - Occurs whenever a mutation gives members of the subpopulation a selective advantage
4 - Over Time - The gene pool of each population changes. The 2 populations are 2 different species |
| What is a Species | A group of organisms that are so similar they can interbreed to produce fertile offspring |
