Domestication of Animals and Crops

Question 1

The four great discoveries of Prehistory

Answer 1

1. Tool
2. The control of fire
3. The invention of the wheel
4. The invention of agriculture

Question 2

What size groups did hunter-gatherers live in?

Answer 2

30-60 individuals

Question 3

When was the shift from hunter-gatherer to farmers?

Answer 3

11,000 BC to 1,500 BC

Question 4

Cause of shift to agricultural lifestyle

Answer 4

• Decline in the availability of wild foods
• Depletion of wild game so less rewarding, easier to gather grain
• Increased technology for collecting, processing and storing wild foods
• Adopt food production or die at the hands of those who have

Question 5

What is the paradox when populations turned to agriculture?

Answer 5

The height and health of people generally declined

Question 6

What is a crop?

Answer 6

Any organism that is harvested by another

Question 7

What is a cultivated crop?

Answer 7

Plants or animals grown via human interference

Question 8

What is a domesticated organism?

Answer 8

Plant or animal brought into the household. Humans often interfere with the reproductive process leading to fundamental genetic changes - these domesticated organisms are different to the wild type

Question 9

What did the transition from wild to cultivated to domesticated involve?

Answer 9

1. Gigantic characteristics
2. A reduction/increase in fertility
3. A loss of survival characteristics
4. Loss of harmful substances
5. Loss of protective structures
6. Loss of delayed germination
7. Early and simultaneous ripening
8. Changes in organ shape
9. Increase in rate of self-pollination

Question 10

What is the FOXP2 gene?

Answer 10

• The first language gene discovered
• Winged helix/forkhead class of transcription factors
• Expressed in multiple tissues and has high level of expression in fetal brain
• This gene allows humans to use such elaborate communication
• Highly conserved, only 3 amino acid differences between humans and mice

Question 11

What is the nucleotide diversity between humans?

Answer 11

0.1-0.4%

Question 12

What is the nucleotide diversity between humans and chimpanzees?

Answer 12

1.2%

Question 13

What is the gene MYH16?

Answer 13

One of several myosin heavy chain genes involved in skeletal muscle formation. The mRNA of the gene is expressed specifically in jaw muscles. High levels of the protein are found in the jaw of primates but not humans. During human evolution, there was a 2 base our deletion leading to frameshift, resulting in a non-functional gene, which is why humans have a much smaller jaw than primates

Question 14

Where did pig domestication occur?

Answer 14

Central Europe, Italy, Northern India and South East Asia, possibly all independently

Question 15

Features of wild boar

Answer 15

48kg
Fat area of 12.6 cm squared
Aggressive and difficult to farm

Question 16

Features of meishan pig

Answer 16

82kg
Fat area of 24.4 cm squared
Domesticated pig bred to provide lots of useful fats for human use

Question 17

Features of pietran pig

Answer 17

117 kg
Fat area of 15.9 cm squared
Domesticated pig bred for lean meat

Question 18

What is the IGF2 gene?

Answer 18

Expressed in prenatal meishan, pietran and wild boar, and helps to form skeletal muscle. In meishan pigs and wild boar, it is only expressed weakly after birth, but in pietran pigs it continues to be strongly expressed after birth. This is due to a silences that prevents further expression of the gene mutating so it can no longer bind to the gene

Question 19

What is polyploidy?

Answer 19

A major mechanism in plant evolution, involving the generation of a chromosome number which is a multiple of some ancestral set - the organism becomes tetraploid rather than diploid

Question 20

How does polyploidy occur?

Answer 20

I’ve either abnormal meiotic (non-disjunction) or mitotic division

Question 21

What is the benefit of tetraploid wheat?

Answer 21

It has two grains per floret rather than one so has much higher yield

Question 22

What was the development of the rachis in the domestication of wheat?

Answer 22

The spiklets of wild (diploid) ears fall apart at ripening through fragmentation of the rachis by shattering. However, the tetraploid forms have a tough rachis that holds the seeds together in a harvestable ear

Question 23

What was the old method of removing the chaff (casing) from the seed?

Answer 23

Parching
Heating the grains by holding them over a fire. It is slow and tedious.
Threshing could not successfully remove the chaff from grains, because the grain was held too tightly by the chaff

Question 24

How is the chaff removed from the seeds of domesticated tetraploid wheat?

Answer 24

Free-threshing
These organisms have a mutation called the Q gene which produced a free-threshing wheat, making the separation of the grain from the chaff easy

Question 25

What does free-threshing preserve?

Answer 25

Gluten. As it is a protein, heating destroys the gluten in wheat flour. Leavened bread cannot be made without gluten

Question 26

What form of polyploidy is seen in current bread wheat?

Answer 26

Hexaploidy - even greater yield

Question 27

What is genetic erosion?

Answer 27

The loss of genetic variation via a reduction in the size of the gene pool

Question 28

What are molecular markers used for?

Answer 28

Pieces of DNA randomly places in the chromosome, used in breeding programmes to follow genes or which the phenotype is difficult to score. The molecular marker must be closely linked to the gene of interest

Question 29

What is a strong selective sweep?

Answer 29

It results in a region of the genome where the advantageous new allele is essentially the only one that exists in the population, resulting in a large reduction in the total genetic variation in that chromosome region

Question 30

What is the dangerous result of a selective sweep?

Answer 30

There is homozygosity not only at the locus of the specific gene, but also at flanking loci owing to ‘hitch-hiking’. The flanking alleles can be ‘bad’ alleles and have a dangerous effect on the carrier

Question 31

What is porcine stress syndrome?

Answer 31

In pigs, there is a gene linked to the IGF2 gene (determines leanness) called RYR1. One allele of this gene is mutated, and if pigs which are homozygous for this gene are subjected to stress or anaesthetic, they die of malignant hypothermia. Pietran pigs with a mutated silencer are homozygous for this gene

Question 32

What has been the main cause of genetic erosion in domesticated species over the last 100 years?

Answer 32

The release of modern cultivars

Question 33

Advantages of modern cultivars (monocultures)

Answer 33

• Uniform product
• Required less farmer input time
• Suitable for big business input

Question 34

Disadvantages of modern cultivars (monocultures)

Answer 34

• Susceptible to change in circumstances (low genetic diversity)
• Requires high input (fertiliser, pesticides, etc)
• Less suitable for small farmers

Question 35

What proportion of world cereal is fed to livestock?

Answer 35

over 1/3

Question 36

When was Dolly the cloned sheep born? How many attempts were made to clone a sheep before it was successful?

Answer 36

July 1996

227 attempts