Adaptation, Natural Selection and The Evolution of Species Flashcards
What do you know about mutations?
A mutation is a random change to the genetic material of an organism.
Mutations occur spontaneously but are rare.
Mutations are the only source of new alleles producing variation,
A mutation can be disadvantageous, advantageous or neutral.
Variation in a population makes it possible for a population to evolve over time in response to changing environmental conditions.
What is an adaptation?
An adaptation is a characteristic that increases the chance of survival and reproducing in a particular environment.
New alleles produced by mutation can result in plants and animals becoming better adapted to their environments.
What do you know about natural selection?
Natural selection is the idea that those best adapted tot whir environments are most likely to survive and breed passing on their characteristics.
Natural selection/survival of the fittest occurs when there are selection pressures :
Abiotic and biotic factors
Evolution is the gradual change in the genetics of a population over time because of natural selection
The peppered moth is an example of natural selection in action
What do you know about speciation?
A species is a group of organisms that can interbreed and produce fertile offspring.
Speciation is the formation of a new species.
Part of a population can become isolated from a species by an isolation barrier.
If different mutations occur in each subpopulation (natural selection will select different mutations in each group due to different selection pressures)
Each sub population will evolve separately until they become so genetically different that they are two different species
Isolation barriers prevent interbreeding between subpopulations and so variation cannot spread between them
Types of barriers include
-geographical
-ecological
-behavioural
Examples of speciation include
Darwin’s finches and St Kilda wrens
