Final - Lecture 3 Flashcards
Impact of constant N over generations on inbreeding?
Not important
- if it changes - recalculate
Impact of constant proportion of males and females on inbreeding?
Not important
- if it changes - recalculate
- wide increase/decrease = not good
Impact of closed population on inbreeding?
Closed = calculation is valid Open = calculation means nothing
Impact random mating has on inbreeding?
A lot of inbreeding can be avoided by careful management
Impact of equal progeny on inbreeding?
Violated quite frequently
- just go back to N and ratio of females and males and recalculate
Impact of discrete generations on inbreeding?
- Population breeds once and that’s it
- both important/unimportant
- exception for species that reproduce and die (e.g. coho salmon)
The engine that powers selection?
Genetic variability
Why are we interested in additive genetic variation?
Only thing that gets passed onto offspring
Genetic variability magnitude influenced by?
- range of allele frequencies of loci involved
- range of associated phenotypic expression for these loci
What is the amount of variability observed equal to?
The range of specific phenotypic loci expressed
When is heterozygosity maxed out?
when p=q=0.5
- maximum variability when we have an abundance of both alleles
Degree to which heterozygotes are expressing dominance?
A lot of genetic variance = not a lot of dominance (mutually exclusive)
- high heritability = high additive genetic variation = low dominance
Alternative expression
codes for different proteins
Tandem repeats
alters amount/rate of expression
- stutters in DNA –> change rate at which DNA is expressed; variability varies depending on the amount of expression (e.g. evolution of bull terrier skull)
What is responsible for black/brown coat in dogs?
Eumelanin
What is responsible for yellow/red coat?
Pheomelanin
C-BARQ tested what?
Show vs. field and black vs. yellow
Runx-2 is responsable for?
Osteroblast differentiation
- associated with bull terrier skull
What happens to additive genetic variation and dominance when heterozygosity decreases due to inbreeding?
They decrease
Inbreeding depression
After some arbitrary number of generations, inbreeding has accumulated in an inbred line
If Aa falls directly between AA and aa, dominance is equal to?
0
What is considered the eraser of inbreeding?
cross-breeding
Cross breeding is also called
Out-crossing
- seeking as much genetic variation with 2 individuals you are trying to breed
What is cross breeding?
Crossing two unrelated (inbred) lines
- creates heterosis
What is heterosis?
Amount of the crossbred mean that exceeds the average of the line means
Suppose f(A) –> 1 and f(a) –> 0, where does additive genetic variation go?
0
Finite Locus Model
Small number of loci with large effects on the phenotype
- selection reaches plateau when f(A) = 1
- selection reduces genetic additive variation = Bulmer effect
- better the progress = less variation
- qualitative traits
Infinitesimal Model
Many loci with small effects on the phenotype
- selection continues forever
- some genetic variation remains
- quantitative traits
