Module 4 Flashcards
Animal Domestication Definition
population of a living organism is genetically changed over generations to benefit humans (for food, work, clothing, medicine)
How many of suitable sized animals were domesticated
14/145
Wild degree of domestication
Untamed
Tamed degree of domestication
useful state
Semi-domesticated degree of domestication
Sill express some wild traits, may be slightly dependent on humans
Domesticated degree of domestication
selected through human management and adapted over generations
How are Adrenal glands adapted by domestication?
Less hormone produced= more tame
How to melanocytes change with domestication?
Coat colour is impacted
How do Chondrocytes change with domestication?
Reduction in skull size
How do odontocytes change with domestication?
reduced number of teeth
Steps to evolution by natural selection
- population of a species has variation
- some variations are more favourable
- more offspring are produced than survive
- those with favourable traits produce more surviving offspring
- favourable trait becomes fixed over time
Natural selection has ___ selection pressure
_______ years
low selection pressure
60 million years
steps to evolution by artificial selection
- population of a domestic species has variation
- humans prefer some variations
- only individuals with desired traits are allowed to reproduce
- breeding stock becomes dominated by trait
- species will change over time so objective is reached
Artificial selection has a _______ selection pressure
high
First domestication species and age
wolf
20,000-40,000 years ago
Difference between a hypothesis and a theory
hypothesis is a proposed explanation based on limited evidence as a starting point
theory is a well confirmed explanation
Russian fox experiment
belyaev selected foxed based on temperament (extremely, moderately, fearful, or quiet) to simulate how wolves turned to dogs
criteria: flight threshold, tamest 10% for breeding stock
Russian fox experiment results
after 40 yrs and 35-40 generations of foxes, 70-80% allow for petting and are considered tame
Morphological associated changes
shorter, wider skulls (overall smaller)
some lines had biannual estrus
floppy ears, curly tails, piebald coats
changes in pattern of neonatal development
7 changes in domesticated species
- increase tameness
- decrease brain size
- floppy ears
- shorter muzzle
- decreased tooth size
- coat colour change
- more frequent estrus cycle
What is tameness
Reduction in release of stress hormones
- reduced fight or flight
- decreased reactivity in new situations
What are the long term and short term stress hormones? where are they produced
long term: Glucocorticoids-cortisol
short term: Catecholamines-epinephrine and norepinephrine
produced in adrenal gland (top of kidney)
what do glucocorticoids do?
regulate duration of neonatal development
What do catecholamines do?
trigger acute stress such as fight/flight
Development of neutral crest
- neutral groove
- neutral tube
- neutral crest cells migrate
Neutral crest hypothesis
domestication = decrease in size of neutral crest cells
population of cells reduced
changes in morphology
How was the wolf domesticated
-wolves that had shorter flight distances could benefit from human food waste
-these wolves breed with each other
-over time they become domesticated (lower stress hormone, lower neural
Co domestication of wolves and humans
humans that were reactive chase animals off
Commensal pathway example and explanation
Cat, dog, chicken, llama
one species obtains food from the other without harming or benefiting each other
PARTNERSHIP
Commensal relationship of cats and age
rodent control, spiritual (in egypt)
9000 yrs ago relationship
3000-5000 yrs ago domestication
Difference between cat and dog domestication
cats have been more fully selected for genes associated with behaviour and neural crest development
Prey pathway example and explaination
Goats, sheep, cattle
evolution of hunting to herd to ranching
sheep domestication times and years
atleast 3 times in the middle east
11000 yrs ago
Struggle with sheep domestication
domesticated for wool production which is unnecessary today. what to do with the wool?
Why were sheep chosen for domestication?
eat everything
valued in some countries
tame in enclosures
herd (gregarious) behaviour
Goat domestication number of breeds and year
10,000 years ago
300+ breeds
Cattle domestication years and duration of domestication
10,000 yrs ago
1000 years to domesticate
M bison x F beef =
infertile offspring
F bison x M beef =
fertile F infertile M
why were ruminants selected
eat what we don’t
make unproductive farmland into productive grazing land
Directed pathway example and explanation
Horse, donkey, camel
used for human labour
is there a single domestication event in directed pathway?
no, wild kept breeding with tame
Horse domestication year
5000 years ago
no wild exists today
Genetic changes in horse domestication
genes related to
fear response
cognative/behaviour
social
learning capability
muscle and limb development
Selections for productivity (4)
Growth rate (avg daily gain)
Milk production (kg per day)
Speed
Learning and training ability
Example of simple dominance in animal breeding
horned vs polled cattle
polled gene has become dominant to reduce injury and ease production ability
