Genome Evolution

Flashcards on key vocabulary and concepts

Heritability

The fraction of the total variance that is due to genetic causes.

VE

Variance within an inbred line

Variation between different inbred lines

VP

Additive genetic variance

Total phenotypic effect is the sum of the independent individual effects of alleles throughout the genome

Non-additive effects

Dominance and Epistatic (Interaction) effects

Narrow-sense heritability (h2 N)

The proportion of the phenotypic variance that is due to additive genetic differences among individuals

Selection differential

The difference in trait mean between all individuals in the parent population and the trait mean of those that reproduced

Evolutionary response to selection

Difference between parental and offspring generation means

Predicting the response of a quantitative trait to directional selection

The Response to selection is predicted by the narrow-sense Heritability x the Selection differential.

Genome-wide association studies (GWAS)

A means of finding locations in the genome that differ most between populations

Polygenic scores

Summarize effect of genetic variants in an individual on their phenotype

Testing for selection in genes

Compare frequency of nonsynonymous and synonymous mutations for that gene to test if a particular gene has undergone recent selection

Synonymous mutations

Result in the same amino acid, no effect on fitness (mostly)

Nonsynonymous mutations

Result in a different amino acid, may impact fitness

Purifying selection

Fewer nonsynonymous substitutions that expected by chance

Positive selection

More nonsynonymous substitutions than expected by chance

The McDonald-Kreitman Test

Compares rates of neutral/non-neutral substitution rates to distinguish within versus between species

Hamilton’s rule

Describes conditions when kin selection will be beneficial- altruistic behavior selected for

Inclusive fitness

Increase to indirect fitness must at least offset cost to direct fitness

Discovery of archaea with characteristics thought to be unique to eukaryotes

Led to the realization that eukaryotes evolved from within a specific clade of archaea

Mitochondria

Result of ancient endosymbiosis with a bacterium – Specifically alpha-proteobacteria

Environmental confounding in genomics

Without randomizing mating & offspring environment, can’t be disentangled