Lecture 35 Evolution & Domestication - Horses Flashcards
Evolution of the horse is reflected in their
-limbs
-teeth
Majority of horse species evolved in
North America
Horses, donkeys, and zebras are in the genus
Equus
Evolution (names) of the Horse
Eohippus —> Oligohippus —>Merychippus —> Pliohippus —> Modern Horse
Oldest known ancestor of the horse is
Eohippus (Hyracotherium)
Hyracotherium (Eohippus) facts (6):
-oldest known ancestor
-fox-sized
-omnivore (3 incisors, 1 canine, 4 premolars, 3 molars)
-feet padded with small hoof like structures in place of nails
-forelimb digits 2-5 weight bearing, digit 1 vestigial
-hindlimb digits 2-4 weight bearing, digits 1 and 5 vestigial
Orohippus facts (7):
-co-existed with Hydracotherium (Eohippus)
-pad footed
-forelimb had 4 digits
-hindlimb had 3 digits
-premolar 1 is smaller
-premolar 4 assumed shape/function of a molar
-crests on teeth more pronounced (grinding)
Mesohippus facts (5):
-legs proportionally larger for running (forests became flatlands)
-3 digits on fore and hind limbs
-majority of weight on digit 3
-3 premolars more molar like (cheek teeth)
-more efficient grinding
Miohippus facts (2):
-co-existed with Mesohippus but over time replaced them
-extra crest in upper molars (ie. equine teeth)
Parahippus facts (4):
-size of small pony
-evolutionary link between ancestral forest horses and plain grazers
-3 digits, digit 3 larger, stronger, and weight bearing
-elongated skull
Merychippus facts (3):
-milestone in evolution of horse
-retained primitive character of 3 digits
-high crowned check teeth for grazing (first known grazing horse)
Horse teeth have
A large crown that continuously grows
Pliohippus facts (4):
-similar appearance to Equus
-3 digits present but medial and later digits are vestigial stubs
-“grandparent” of modern horse
-gave rise to Dinohippus
Dinohippus facts (1):
Closest relative to genus Equus
Equus facts (3):
-only surviving genus of the horse family
-found on every continent except Australia and Antarctica
-two wild species
Two wild species of Equus are
-Tarzan (Equus ferus ferus) now extinct
-Przewalski’s Horse (Equus ferus przewalskii)
Equus caballus
Modern domestic horse
Domestication of horses is debatable because (2)
-horses are extremely diverse
-horses are very widespread
Genetic data has traced all domesticated horses to (2)
-one founder stallion
-at least 77 mares
Domestication of the horse occurred
Twice
In Botai culture in Kazakhstan, evidence of horse domestication is found (3)
- metacarpals (cannon bone) found
- Fatty lipids of horse milk found inside pots (horses kept for meat and milk)
- Bit wear on horse teeth
The horses domesticated in Botai are (2)
-not related to the modern horse
-gave rise to Przewalski’s horse
Horse genome diversity has decreased due to (2)
-development of pure breeds
-decrease in draft breeds
Myostatin gene is (3)
-the “Thoroughbred Gene”
-responsible for speed and precocity
-inhibits muscle cell growth
SNP stands for __ and influences ___
Single nucleotide polymorphism; speed
A horse with SNP with C/C is best suited for
Fast, short distance sprints
A horse with SNP C/T is best suited for
Middle-distance races
A horse with SNP T/T is best suited for
Long-distance races (greater stamina)
