Evolutionary Biology 15: Levels of selection

Question 1

Levels of selection?

Answer 1

Gene (Genotype)
Groups of Gene (Chromosomes, Genome)
Phenotype
Individual
Groups of individuals (Populations)
Species

Question 2

Example of genetic selection?

Answer 2

Antibiotic resistance in Bacteria

Question 3

Examples of conflict between levels of selection?

Answer 3

Mouse t Haplotype

T - normal ‘allele’, several t ‘alleles’
tt males are sterile

BUT - Heterozygous Tt males transmit t allele to 99% of sperm (not 50%)

t allele detrimental to individual TtxTt 25% chance offspring are sterile

Question 4

What would happen if tt was not lethal in mouse?

Answer 4

t would displace T (T would go extinct)

Question 5

Example of phenotype selection?

Answer 5

Dark phenotype in C. intermedius found around volcanoes

• mutation in MC1R gene causes perfect dark phenotype
• independent evolution of different populations withdark phenotype did not show this mutation
• > selection on phenotype (response from different genes)

Question 6

What is and what is the problem with group selection?

Answer 6

Natural selection among groups

• Individual selection will occur within populations and will likely be stronger
• Individuals that benefit others at expense to themselves will likely be selected against

Other problem -> Kin selection (form of group selection) can be considered just an extension of individual selection

Question 7

What is meant by kin selection?

Answer 7

Inclusive Fitness

Colonies are families

-> workers / queens are not genetically different, only conditional expression of same genome

-> helping the queen indirectly
spreads worker genes

Kin selection is an extension of individual selection