Quantitive Genetic Variation Flashcards
H-W Equilibrium
1) Describes change in Allele/Genotype frequency
2) Describes diversity at a single locas
What factors influence genetic diversity?
-Selection
-Reproductive Fitness
-Evolutionary Potential
These generally don’t act on single loci. They act on quantitive characters.
What are quantitive characters?
They are polygenic meaning controlled by multiple loci, eg. Body weight, muscle mass, visual acuity.
Most important Quant chars are related to reproductive fitness.
Reproductive Fitness
‘Number of fertile offspring produced by an individual that survive to reproductive age’
-Mating ability, fertility and longevity. Critical commodities for endangered species.
Quantitive characters and their importance in conservation
Quantitive variation for fitness characters benefits survival. If a species looses quantitive variation for fitness.
Short term- leads to inbreeding depression. Long term- leads to loss of evolutionary potential. Different data, measures molecular genetic diversity alone give poor estimates of evolutionary potential.
What % of quantitive variation is heritable?
Measure quant char in male and female parents= Parental means.
Measure quant char in offspring= offspring means.
Collect data for many family groups. Fits a regression line. Slope of line indicated how much variation is due to heritability.
Heritability
- Proportion of total phenotypic variance in a population due to genetic differences among individuals
- Only portion of phenotypic variance transmitted from parents to offspring
- Degree of heritability determines the evolutionary potential of a quantitive character
- No heritable variation, then no evolutionary potential.
Low heritable may be a problem for endangered species
Genetic diversity is generally lower in endangered species relative to non-endangered species. Therefore, we might assume that heritability is lower in endangered species. Not enough data to test this yet?
