20) Evolution Flashcards
What is evolution
Change in allele freuquency.
CHange range of alleles ( gene pool)
What is Natural Selection
Predation, disease and selection pressure creates struggle for survival
Some are adapted , has alleles that inc chance of survival, more likely to survive,reproduce and pass advantageous allele.
What is stabilising Selection
Environment isn’t changing mych
Middle range more likely to survive and reproduce.
Reduce range of phenotypes
What is directional selection
Change in environment Characteristics of extremes most likely to survive
What is Genetic DRift
Chance dictates which alleles are passed on.
By chance allele of one Genotype is passed on.
Haas a greater effect on smaller populations , as chance has a greater influence.
What is a Genetic Bottleneck
An event that causes a big reduction in a population size , reducing the gene pool ( overall range of alleles)
Genetic Drift has greater effect if there is a genetic bottleneck
What is the Founder effect
Few organisms from a population start a new population.
Reduce genetic variation as more small
What is Hardy-Weinburg principles
Predict allele frequency won’t change.
Only true under :
- no immigration , emigration , mutation or natural selection.
What are the equations of the Hardy-weinberg Equations
Allele Frequency
p + q = 1
Genotype frequency
p^2 + 2pq + q^2 = 1
p^2 = Homozyg Domin
2pq = Heteroz
q^2 = Homozyg Recc
What is artificial Selection
Human select individuals breed together to get desirable traits.
How does Artificial Selection Reduces Gene pool
Similar traits = similar alleles
Reduce no. of alleles
All is susceptible to the same disease
Potential useful alleles can be lost
What is speciation
Similar organism that can reproduce to give fertile offspring
What is Allopatric Speciation
Geographical isolation
-Physical barriers divides population
Allele frequ will change on eachside due to mutation or adaptions passed
