Selection Flashcards
Natural selection?
The driving force for adaptive evolution
Charles Darwin - 1859
1. in all organisms, more offspring than can survive and reproduce
2. organisms differ in their ability to survive and reproduce, some of these differences are due to genotype
–> leads to survival of the fittest and progressive improvement and adaptation
what level is selection at?
the phenotypic level
can be analysed at the genotypic level
can never be analysed at the allele
what is fitness represented by?
W = relative fitness (relative to selection)
whats the fitness of a neutral genotype?
1 - no selection against it
fitness of a genotype against which there is selection?
W = 1 - S
what is the selection coefficient?
S (1 - W) - represents reduction of fitness of selected genotype compared to the other genotype
if there is strong selection?
the population can become fixed for an allele (directional selection)
what is heterozygote disadvantage / inferiority?
underdominance
degrees of dominance: complete dominance?
AA = 1 Aa = 1 aa = 1 - S
degrees of dominance: Additive (no dominance)?
AA = 1 Aa = 1 - 0.5 x S aa = 1 - S (h = 0.5)
degrees of dominance: Partial dominance?
AA = 1
Aa = 1 - hS
aa = 1 - S
(0
degrees of dominance: Recessive dominance?
AA = 1 - S Aa = 1 - S aa = 1
degrees of dominance: heterozygote advantage?
AA = 1 - S Aa = 1 aa = 1 - t
degrees of dominance: heterozygote disadvantage?
AA = 1 Aa = 1 - S aa = 1
