Evolution and domestication of the horse, micro-evolutionary consequences, related species, inter-species hybrids. Flashcards
Taxonomy: Kingdom, Phylus, Class, Family, Genus
kingdom: animalia,
phylum: chordata,
class: mammalia,
order: Perissodactyla (non-ruminant, hooved animals)
Family: Equidae
name x4 subgenus
Equus,
Asinus (equus asinus/ africanus) (domesticated ass),
Hemionus (asian semi-ass),
hippotigris (zebra).
x4 different species of subgenus equus + latin name
Wild horses – Equus ferus Boddaert,
Prewalski horse/Taki – Equus ferus Prewalski,
Tarpan – Equus ferus ferus,
Domestic horse – Equus caballus.
x5 interspecies hybridisation
Mule – Male donkey (jack) & female horse (mare). Usually sterile.
Hinny – Female donkey (jennet) & male horse (stallion). Less common. Also infertile.
zorse - female horse (mare) + male zebra (stallion)
zebra hinny: female zebra + male horse (stallion)
zebroid: female donkey (jennet) + male zebra (stallion)
What is Haldane’s Rule
primarily the heterogametic sex (male) is affected by sterility in successful crossing of closely related species.
x6 evolutionary forms of the horse (transitional species)
Evolution is well documented.
approx. 60 million year process.
Eohippus,
Mesohippus,
Mio-, mery-, pliohipps,
Equus.
micro-evolutionary consequences:
x4 most important changes in modern horse
Size,
toe reduction (4 –> 1),
diet (omnivores -> herbivores),
teeth,
forest –> pasture
where and when did domestication take place?
Occurred ~5000-6000 years ago.
1st – Central Asia,
later in Persia,
Egypt & Europe (3000-4000BC).
what is the main ancestor of the modern horse?
Based on mitochondrial examination, Tarpan/Tarpan subspecies is main ancestor.
what is the ‘wild’ horse?
Przewalkski horse is only remaining wild spp
what are feral horses?
Have domestic ancestors but were born & live in wild
(‘dedomesticated’) -> Mustangs, Bramby
when did horses arrive back into america after extinciton?
after 1492 due to Spanish invaders
name some historical uses of horses
hunting,
chariots,
carriage,
coach,
transport,
military,
agricultural,
leisure.
ancestors of the modern horse
tarpan (extinct),
west european forest horse,
przewalski,
mingolian taki,
mustang + bramby (returned to wild).
micro-evolutionary consequences:
x10 consequences of domestication…
FMSBWDARCS
Fusion of chromosomes,
Mutations and selection,
Size variation,
Build + conformation,
Weight variation (50 - 1200kg),
Diet,
Accelerated ageing,
Reduced immune system,
Colour variations (bay, grey, dun, chestnut, palomino, buckskin).
Sexual activity.
forest –> pasture.
Fusion of chromosomes: number of chromosomes in wild horses, asses, domestic horses, tarpan.
wild + domestic horses - 66 - > 64 presumption only,
ass - 62,
tarpan - unknown.
mutations and selection: how many breeds are there?
much more diversity.
200+ breeds, breed groups and types.
many new mutations + harmful genetic diseases e.g. HWSD.
there is a high allelic polymorphism on the same gene locus across breeds.
what type of size variations may occur?
size has increased immensely.
height is taken at withers.
under 148cm - pony.
over 148cm = horse.
dwarfism: falabella + shetland pony.
mention build and conformation differences due to breeding
draft horses (heavy).
light horses.
certain breed characteristics - roman nosed + dish-faced.
what is the effect of domestication on diet?
less effective feed conversion.
what is the effect of domestication on immunity?
reduced immunity.
increased sensitivity to certain diseases e.g. respiratory diseases.
what is the effect of domestication on sexual activity? (x3)
poorly expressed sexual dimorphism.
reduced fertility in some breeds.
was monoestrus, now seasonally polyoestrus.
