Genetic Diversity Flashcards
What is genetic diversity?
The total number of different alleles in a population
A large number of different alleles in a species/population means?
High genetic diversity
Why is genetic diversity important?
If an environment changes, high genetic diversity increases chance of adaption to new environment
What increases genetic diversity?
Mutations in DNA forms new alleles
Gene flow when different alleles introduces into population due to migration and reproduction
Genetic bottleneck
Event that causes big reduction in population eg deaths before reproducing
How do genetic bottlenecks reduce genetic variation?
Large number of deaths of individuals caused by genetic bottleneck so certain alleles are lost: all individuals possessing these alleles die
So when the remaining population reproduces, the genetic diversity is lowered than before bottleneck due to lost alleles
The founder effect
When a few organisms from a population start a new colony separate from the rest of the population.
This lowers genetic diversity of this founder population
Why is the founder population’s genetic diversity reduced?
Because there are smaller number of different alleles in initial founder gene pool compared to whole population.
So after they reproduce, there is little genetic diversity compared to whole population
4 ways to measure genetic diversity
Observation
Mutations
Amino acid sequence
Immunology
Observation to measure genetic diversity
Different number of alleles encode for different polypeptides thus cause different observable characteristics within phenotype.
So find frequency of these observable characteristics = variety of different alleles
Mutations to measure genetic diversity
Comparing the same allele across different species/ within species to find frequency of different bases to show how many mutations of single base substitutions occurred.
More differences = more evolutionary divergence
Amino acid sequence to measure genetic diversity
Select common polypeptide chain and find frequency of amino acid differences in 1° structure.
Because variation in alleles change mRNA transcribed thus amino acid sequence of polypeptide chain
The less genetically related….
The more differences in amino acid sequence/mutations/observable characteristics and less similarities in these across the species/within the species
Thus showing more genetic variation and so diversity
Immunology techniques to find genetic diversity
Extracting a shared protein across different individuals and using it as an antigen to see the relative binding ability to the same antibody.
Why does the immunology technique work
B cells release antibodies complementary to the antigen (protein) of our selected organism
To produce antibody-antigen complex
Comparing to other organisms: if the same antibody binds more (produces more complexes) it is closely related or if binds less (less complexes) it is distantly related
Why does the immunology technique work
B cells release antibodies complementary to the antigen (protein) of our selected organism
To produce antibody-antigen complex
Comparing to other organisms: if the same antibody binds more (produces more complexes) it is closely related or if binds less (less complexes) it is distantly related
Limitations of observation method
Observable characteristics are controlled by many alleles: hard to determine exact variation in no. Of alleles
Phenotype can be affected by environment
Hard to categorise observable characteristics
How do mutations increase genetic diversity?
Causes a change in base sequence of dna spontaneously
Leads to creation of new allele that encodes for a new polypeptide synthesised so new phenotype expressed
