1: What causes diversity? Flashcards
(23 cards)
Define standing genetic variation
= The no. of alternative alleles for a gene at a given locus in the pop.
What is the level of standing genetic variation a predictor of?
The populations potential to evolve and adapt
What maintains diversity?
Sex
Ploidy
Balancing selection
- Heterozygous advantage
- Frequency-dependent selection
What do somatic mutations affect?
Individuals but NOT the pop.
What can germline mutations affect?
Germline mutations affect the whole pop.
Describe structural mutations
Changes happen at whole region level of chromosome
Deletion mutation
region deleted
Duplication mutation
region duplicated
Inversion
region flipped
= Limit recombination
Subsitution mutation
moved from one region to another
Translocation mutation
regions swap
Synonymous/silent mutations
codon changes but amino acid stays the same
Non-synonymous
amino acid is altered
Define missense mutations
change in single amino acid = alters protein function, reactivity etc.
What do frame shift mutations effect?
impacts every codon downstream from mutation
Describe the sex mutation bias
Sex bias: males generally have a higher mutation rate
Males produce more gametes so germline mutations are more common
Define Independent assortment
Chromosomes randomly oriented in metaphase I → assortment of maternal + paternal copies is diff in the resulting gametes (Mendel’s Law)
Define random fertilisation
Any sperm can fertilise any egg, so each zygote is a diff combo
Define recombination
Shuffling of genetic material between maternal + paternal chromosomes during meiosis
Give an example of heterozygous advantage
E.g Sickle Cell Anaemia
- Homozygous dominant = normal haemoglobin
- Heterozygous = sickle cell trait (minor health issues), malaria resistant
- Homozygous recessive = Severe sickle cell anaemia
- Heterozygote common in pop.s with high incidence of malaria
What is frequency dependent selection?
the fitness of an allele changes depending on how common it is
Describe positive frequency dependent selection
(strength in numbers)
Fitness & frequency + correlated
Fitness increases when alleles becomes more common
Describe negative frequency dependent selection
(advantage in being rare)
Fitness & frequency negatively correlated
Fitness decreases when allele becomes more common
