8. Human-Mediated Evolution

Question 1

Human-mediated Evolution

Answer 1

Evolution which occurs as a result of human activities

• Intentional activities
• Unintended consequences

Question 2

Intentional Activities

Answer 2

Much faster than in the wild
Only isolated sub-populations of a species is impacted
- Artificial selection (Human-directed evolution)

Question 3

Artificial Selection

Answer 3

Human-directed evolution

• Traditional Breeding
• Genetic Engineering

Question 4

Traditional Breeding

Answer 4

Selection for pre-existing traits in a species - Only individuals with perceived beneficial traits reproduce

• Directional selection
• Much faster than wild
• Plant Breeding & Animal Husbandry

Question 5

Plant Breeding

Answer 5

Believed to have emerged with agriculture
- all modern crop derives from selective plant breeding
Desirable Traits
- High yield
- Disease Resistance
- Better taste
- Easier to harvest
- Ease of hybridization
The same plant can be bred for different traits

Question 6

Animal Husbandry

Answer 6

Predates plant breeding
Not only ungulates - Cow, sheep, pig
- Insects - Silkworms / Bees
- Aquatic - Molluscs, Fish

Question 7

Domestication

Answer 7

The first step of animal breeding

• An organism assumes responsibility for the care ad reproduction of the second organism
• The first organism derives benefit from the organism under its care
• Domesticated individuals usually express phenotypes differentiating them from the wildtypes

Question 8

Taming

Answer 8

Conditioned behavior in a wild-born animal involving reducing the natural avoidance response to humans

Question 9

Animal husbandry

Answer 9

Desirable traits:

• Ability to be domesticated - most seem to be impossible to do so
• Harvestable commodity
• Useful role
• Hybridization rare - Except mules

Question 10

Population Sire Effect

Answer 10

Offspring from the desirable individual will make up a disproportionately large proportion
- The deleterious trait will also be overrepresented
A type of population bottleneck

Question 11

Limitation of traditional breeding

Answer 11

• Only pre-existing traits can be selected
• Limited number of species that ban hybridize
• Solved by genetic engineering

Question 12

Genetic Engineering

Answer 12

Induced, intentional mutation
- somatic or germ-line
Generally appropriate natural system for lateral gene transfer

Question 13

Agrobacterium tumefaciens

Answer 13

Parasitic bacteria
- Inserts own DNA into plants
Crown gall disease
Problems
- No control over where it inserts the gene
- have to test each plant to check insertion
- Only infected cells will be changed

Question 14

Agrobacterium tumefaciens

Transforming all cells

Answer 14

• Embryo harvested and multiplied
• Transformed
• The ones with the right insertion grown into mature plants
  Problems
• Not all plants grow well on medium
• Many years and money required just to develop method to grow plant in medium

Question 15

CRISPR/Cas9

Answer 15

• Prokaryotic defense mechanism

Allows to specifically choose which genes to cut out and what to insert

Question 16

Gene drive technology

Answer 16

If CRISPR/Cas9 given to one gamete, the embryo will modify the genes from the other
- Guaranteed inheritance

Question 17

Unintended Consequences

Answer 17

• Pollution
• Founder effect of invasive species
• Population bottlenecks in native species
• Artificial landscapes
• Pesticide - Insect and weed genes
• Antibiotic
• Failed biological control - invasive species basically
• Genedrive - What if it escapes
• Unintended natural selection - The worm in heavy metal
• Hiking trails - invasive plants