Evolution Of Species Flashcards
What is a mutation?
A mutation is a random change to genetic material
What effects do mutations have on organisms?
They can be neutral or can confer a disadvantage or a advantage to survival.
When do mutations occur?
They are spontaneous and the only source of new alleles
What factors can increase the rate of mutation?
Environmental factors, such as radiation and some chemicals.
What can new alleles result in?
Plays and animals becoming better adapted to their environment
Why is variation important?
Variation within a population makes it possible for a population to evolve over time in response to a change in environmental conditions.
What is an adaption?
An adaption is an inherited characteristic that makes an organism well suited to survival in its environment/niche
When does natural selection occur?
Natural selection or survival of the fittest occurs when there are selection pressures.
How does natural selection work?
The best adapted individuals in a population survive to reproduce, passing on the favourable alleles that confer the selective advantage. These allies increase in frequency with the population.
What do species produce?
More offspring than the environment can sustain.
When does speciation occur?
After part of a population becomes isolated by an isolation barrier.
What is an isolation barrier?
It separates a population. It can be geographical, ecological or behavioural.
What mutations occur in the separated populations? And why?
Different mutations occur in each sub-population. Natural selection selects for different mutations in each group, due to different selection pressures.
How does a population become two different species?
Each sub-population evolves until they become so genetically different that they are two different species.
What re some examples of isolation barriers?
- geographical: ocean, mountains, deserts
- ecological: ph, salinity, temp or moisture.
- behavioural: wrong courtship behaviour
