Natural Selection, Courtship, Variation Flashcards
What are the three genetic factors influencing variation?
- Random mutations
- Meiosis
- Random fertilisation of gametes
What is continuous variation?
Variation producing a normal distribution curve - range of phenotypes between 2 extremes
What is discontinuous variation?
Characteristics usually controlled by one gene — organisms fit into a few distinct categories — little to no environmental influence
Summarise evolution by natural selection
Natural selection gives some alleles a better chance of survival than others. Over many generations, populations may gradually change, becoming better adapted to their environments.
What is stabilising selection?
Selection that selects against and eliminated extreme phenotypes, preserving the average phenotype
What is directional selection?
Selection favouring extreme phenotypes, causing the mean to shift to an extreme
What is disruptive selection?
Selection favouring individuals with extreme phenotypes rather than those around the mean
Why is courtship essential?
Enables individuals to:
- Recognise members of their own species
- Identify a mate that is capable of breeding
- Form a bond
- Synchronise mating
What are the 3 components to biodiversity?
- Species diversity
- Genetic diversity
- Ecosystem diversity
What is species diversity?
Refers to the number of different species (richness) and the number of individuals in each species (evenness) within a community
What is genetic diversity?
Refers to the variety of genes belonging to the individuals in a population of each species
What is ecosystem diversity?
Refers to the range of different habitats
