Transcript Horse Pedigrees and Coat Color Genetics

Horse Genetics and Genealogy
Horse Winter Series
28 February 2016
4H, URI
Summary of Today’s Topics
 How to read horse pedigrees
 Basics of Genetics
 Horse Coat Color Genetics overly simplified!
 Genetic crosses for color
Horse Pedigrees
Like genealogy for horses
Trace Pedigrees for Breeding
 Make sure the horses are from different lines
 Choose traits to increase the likelihood of getting the kind of
foal you want
 Do genetic testing to make sure that a foal will be healthy
American Pharoah
http://www.pedigreequery.com/american+pharoah
http://hawaii.hawaii.edu/math/Courses/Math100/
Chapter1/Notes/Exercises/Prac121.htm
Secretariat
To read a pedigree
 Top line represents all the males
 Bottom line represents all the females
 Pink is for girls, blue is for boys
 Information about when born, where born
Appaloosa pedigree
Basics of Genetics
Works the same for people and horses
DNA
https://sites.psu.edu
Organized into Chromosomes
Horse chromosomes
Comparing people to horses
 People have 23 pairs of
 Horses have 32 pairs of
chromosomes
 Individuals give ½ their
chromosomes to their kids
 Kids get 23 from mom and
23 from dad
chromosomes
 Horses give ½ their
chromosomes to their kids
 Horses get 32 from Sire
and 32 from Dam
Genes are on chromosomes
http://www.genomenewsnetwork.org/
Get 2 copies of a Gene
 Each copy is called an Allele
 You get one allele from mom, one allele from dad
http://biology.about.com/od/geneticsglossary/g/a
lleles.htm
Alleles vary in strength
 Some are dominant, usually represented with capital letters
 AA, EE, Aa, Ee all look the same
 Some are recessive, represented with lower case letters.
 aa, ee look different
Coat color and pattern are controlled
by A LOT of genes!
Horse pattern
BTW, this was photoshopped!
http://www.snopes.com/photos/animals/horsehor
se.asp
Appaloosa
www.dfappaloosas.com
Coat Color
Ridiculously simplified, because it’s ridiculously complex
Coat color results from pigments
 More than 10 genes give color
 Base color of all horses Black or Chestnut
 Two main pigments controlled by gene E (which is a covering
gene, called the Extension gene)
 3 alleles, E+ , e, ea
 Eumelanin – Black E+
 Phaeomelanin – Red for chestnut e, ea
 Black horse E+E+, E+e or E+ea
 Chestnut ee or eea or eaea
Black – have eumelanin
Have the genotype E+E+, E+e or E+ea
http://www.theequinest.com/colors/base/black/
Chestnut – have phaeomelanin
Have the genotype ee or eea or eaea
http://www.theequinest.com/colors/base/black/
Color Modifiers
 Distribution of black pigment is the agouti gene – A
 4 alleles, A+, AA, At , Aa
 Makes body color different from the main, tail and points
 Bay coloring
http://www.theequinest.com/colors/modifiers/ba
y/
Grey Horse Color Modifier
http://www.theequinest.com/colors/modifiers/gr
eying/
G gene
 2 alleles, G+ or GG
 3 possible combinations
 G+ G+
 G+ GG
 GG GG
Dilution Genes
 Dun - have dorsal stripe
 Crème – palomino, cremello and buckskin
 Silver – affects black pigment
 Champagne – turns red pigment golden (grullo)
 Pearl
 Mushroom (not all breeds)
Dun
Creme
Silver
Champagne
Image from Kumana @ Wild Equines
Pattern has another suite of genes
 Roan
 Pinto
 Appaloosa
 Rabicano
http://www.theequinest.com/colors/whitepatterns/pinto/
Appaloosa
Predict the foal color
Try some Genetic Crosses with horse color
All horses are B+ B+
 We ignore this gene and concentrate on the other 2 genes, E
and A, extension and agouti
Base Coat Gene E
 Base color of all horses Black or Chestnut
 3 alleles, E+ , e, ea
 Eumelanin – Black E+
 Phaeomelanin – Red for chestnut e, ea
 Black horse E+E+, E+e or E+ea
 Chestnut ee or eea or eaea
Black mare with a Black stallion
Black stallion
Black Mare
E+
E+
E+
E+
Black
E+
E+ E+
Black
E+
E+ E+
Black
E+ E+
Black
What if they weren’t E+E+?
Black stallion
Black Mare
E+
E+
e
E+ E+
E+ e
Black
e
E+ e
Black
Black
e e
Chestnut
To breed bay horses
Black Mare E+e
Black stallion E+ea
AA
AA
AA AA
Bay
AA Aa
Aa
AA Aa
Bay
Aa Aa
Aa
Bay
All Black
What is your favorite color horse?
 Think about what it’s genotype might be
 What other genotype would you cross with it to get the same
color foal?
Website to do it for you!
http://www.animalgenetics.us/Equine/
Check out these websites
 http://www.horse-genetics.com/horse-colors.html
 http://www.theequinest.com/
 http://www.mustangs4us.com/Horse%20Colors/genes1.ht
m
 http://www.animalgenetics.us/Equine/