Paper 1: Genetic diversity Flashcards
Genetic diversity
No. of diff alleles in a population
Genetic diversity is a factor that enables…
Natural selection to occur
The principles of natural selection in the evolution of populations [5]:
- Random mutation can result in a new allele of a gene
- in certain situations mutations may benefit posessor
- Increases reproductive success
- Advantageous allele is then inherited by the next generation
- over time new allele increases in frequency in the population
What does natural selection result in? [2]:
- results in species that are better adapted to their environment
- adaptations may be anatomical, physiological or behavioural
What other than genetic factors produces genetic variation? [4]:
- crossing over
- Independent seggregation
- Random fertilisation
- Mutations in DNA
Homologous chromosome
Carry the same genes at the same loci but they have different alleles
whats independent segregation?
when chromosomes are randomly assorted in the gametes
Types of mutation [DIDAS]:
deletions inversions duplications additions substittions
Nondisjunction
Occurs when homologous chromosomes do not separate into individual cells at the end of meiosis 1
What does nondisjunction result in?
Gametes w/ extra chromosomes/ extra parts
how u get doen syndrome/ trisomy 21?
egg cells went thru non disjunction
when are mutations passed down to offspring?
when they happen in the gametes/ sex cells
Why is Variation Good? [3]:
- Individuals have diff allele combinations
- Some will be advantageous
- Individual w/ advantage has a greater chance of survival
Bottleneck effect [4]:
- Catastrophic event occurs that decreases population
= decreased gene pool size - so no. of alleles in new population is smol
- decrease in genetic diversity
Founders effect [3]:
- Small no. of individuals decide to leave the larger population & migrate
- They reproduce but gene pool a lot smaller
- Interbreeding causes no gene flow so gene pool stays small
