Coat Color Genetics Flashcards
what kind of trait is coat color and why?
qualitative; even though there are so many genes involved it still can be put into categories
what are the 2 starting point options for coat color for horses that all other genes only modify?
black or red
how are genes named? (2)
- in reference to their role in a biological pathway
- for the disease/condition in which they were first associated
all with no clear association with the particular phenotype
what is the longer name for gene E?
MCR1
what is gene E? (2)
- the extension gene
- determines if horse is red or black
what is dominant and recessive for gene E?
black is dominant (E)
red is recessive (ee)
does gene E determine pattern or placement of black pigment on a horse?
no; that is up to other genes
as controlled by genes OTHER than E, where can black hairs be found on a horse? (2)
- either in a distinctive pattern on the points (legs, mane, tail)
- or all over the entire body
what is the phenotype of EE or Ee?
black pigment in hair and skin
what is the phenotype of ee?
horse has black pigment in skin, but hair pigment appears red
describe the range of coat colors from ee (3)
- some shade of red, with NO black points
- ranging from liver chestnut to dark chestnut to chesnut or sorrel
- may have mane and tail that are dark red or brown
describe EE (4)
- no red factor detected
- cannot have red foals, regardless of the color of the mate
- base color is black, bay, or brown
- includes buckskin, zebra dun, grullo, perlino, gray, tobiano, overo, roan, or appaloosa
describe Ee (4)
- both black and red factoes detected
- can transmit either E or e to offspring
- base color of the horse is black, bay, or brown
- includes buckskin, zebra dun, grullo, perlino, gray, tobiano, overo, roan, or appaloosa
describe ee (3)
- only red factor detected
- base color is sorrel or chestnut (same thing = red)
- includes palomino, red dun, gray, cremello, tobiano, overo, roan, or appaloosa
describe the manes and tails of ee horses
manes and tails may be lighter (flaxen), or darker (BUT NOT BLACK), or could just be same color as the rest of the body
describe the confusing shit about chestnut and sorrel
they are the same color: red; just used in different areas;
AQHA says sorrel, byt thoroughbred people say chestnut
if you mate two ee horses, what color horse will you get?
only some shade of red because offspring will have to be ee
what is the longer name for gene A?
agouti signaling protein/agouti gene
what does gene A determine?
distribution of black pigmented hair
what does a dominant A in combination with dominant E yield?
will confine the black hair to the points to produce a BAY
describe the various shades of bay
range from dark bay (brown) through mahogany, blood, copper, and light bay
what are the 4 varations of the agouti gene? list in order of most to least dominant
- A+
- A
- At
- a
what must a horse have in its genotype in order to be a bay?
MUST have a dominant E and a dominant A
does the recessive agouti allele restrict the distribution of black hair? give what genotypes yield a uniformly black horse
no; because (aa) in the presence of the E allele produces a uniformly black horse
black: EE or Ee aa