BIO 115 Lecture Notes - Lecture 24: Wood Mouse, Quantitative Trait Locus, Reaction Norm
Charlie Kent
Bio 115
2017 Fall
Human Biology
● Expression of agouti during development influences coat colour
○ Development of baby mice in the extreme phenotypes
○ They wre happening very early on in development: pigmentation
○ In these mice you could see the expression of agouti very early relative to when
they thought it would be expressed
○ Agouti rather than turning on or off pigmentation, it was reposnsible where the
pattern of cells would be laid on the mice
■ Mainland mice: agouti allele ends up with the patterning all along the side
and top of the mouse
■ Meach lineage: particular allele laif down a different margin allele
● Mice aren’t really white, they have a light strip of brown along
their back.
● Genetic manipulation of dark mice makes them lighter
○ Figured which section of the chromosome determine the patterns
○ Located this section
○ Made genetically engineered mice where they removed the section from mainland
mice and inserted it into the beach mice
■ Ended up with mice looking like the mainland ines
○ The section of the genome responsible for coat colour was therefore discovered.
● Key concept:
○ QTL mapping identifies regions of the genome associated with phenotypic
variation
■ First step toward discovering which of multiple genes responsible for
phenotypic evolution
● Phenotypic plasiticity:
○ A single genotype produces different phenotypes depending on the environment
■ Plants for example
● High light enviro: tend to produce many but smaller leaves
○ Are able to photosynthesize more
● Low light enviro: fewer but larger leaves
○ Larger leaves have better time capturing the light that they
have access to.
● Reactive norm can predict response to environment
○ Can measure how phenotypes vary in environments
○ When you measure the phenotype with the same genotypes across different
environments= reaction norm
● GXE interactions: phenotypic plasticity of C. Elegans
○ Different genotypes have different reaction norms,
○ Top two panels: different traits under the same enviro gradient=temperature.
■ A: age of maturity in days.
● Different blue liens=different genotypes.
Document Summary
Expression of agouti during development influences coat colour. Development of baby mice in the extreme phenotypes. They wre happening very early on in development: pigmentation. In these mice you could see the expression of agouti very early relative to when. Agouti rather than turning on or off pigmentation, it was reposnsible where the they thought it would be expressed pattern of cells would be laid on the mice. Mainland mice: agouti allele ends up with the patterning all along the side and top of the mouse. Meach lineage: particular allele laif down a different margin allele. Mice aren"t really white, they have a light strip of brown along. Genetic manipulation of dark mice makes them lighter their back. Figured which section of the chromosome determine the patterns. Made genetically engineered mice where they removed the section from mainland mice and inserted it into the beach mice. Ended up with mice looking like the mainland ines.
