L18. Human Impacts: Agriculture

Question 1

How have humans impacted the earth’s physical environment?

Answer 1

• changing the composition of the atmosphere
• redistribution of plant biomass
• redistribution of inorganic material
• redistribution of water
• changing albedo
• changes in biodiversity
• pollution
• light and noise
• radiation

Question 2

How have humans impacted evolution of other organisms?

Answer 2

• domestication
• changing selection pressures
• removal/extirpation
• new niches/environments
• adding mutagens to the environment
• GMOs

Question 3

Agriculture as a big driver of physical and evolutionary change

Question 4

Domestication

Answer 4

a change in the gene pool of a plant or animal resulting from a coevolutionary process
- could happen through artificial selection

Question 5

Artificial selection

Answer 5

humans manipulate plant or animal breeding to selectively develop particular phenotypic traits by choosing which males and females will reproduce or allowing reproduction/survival to occur in a controlled environment

Question 6

Modern desires in animal artificial selection

Answer 6

• ability to survive stress
• high production
• ability to survive on cheap food
• can select for diseases resistance, but also heavy reliance on anti-biotics

Question 7

Green revolution

Answer 7

• selected for: dwarf crop varieties and cultivars with higher tolerance for certain conditions
• synthetic nitrogen fertilizer
• agrochemicals
• increased mechanization
• increased irrigation
• consolidation of land (larger farms)

Question 8

Modern desires for plant artificial selection

Answer 8

• resistance to herbicides
• production of non-viable seed
• uniform germination and maturation times
• uniform grain size
• disease and pest resistance
• high yield
• herbicide tolerance
• food quality
• storage quality
• modified to not produce viable seeds, meaning farmers have to re-buy each year

Overall highly reduced biodiversity (genetic bottleneck?)

Question 9

GMOS

Answer 9

organism whose genetic material has been artificially manipulated in a laboratory through genetic engineering
- creates combinations of plant, animal, bacteria, and virus genes that do not occur in nature or through traditional crossbreeding methods
- potential for hybridization which could maybe be a problem but hasn’t been yet

Question 10

Anti-biotic resistance

Answer 10

• antibiotic use is widespread in agriculture for increasing yield and enabling high density
• significant concerns about loss of effectiveness and spread
• resistance to pesticides
• creation of superbugs

Question 11

Ecosystem displacement

Answer 11

• 37% of earth is used for agriculture of some kind (agriculture is big source of carbon dioxide, nitrous oxide, methane)
• displacement and fragmentation is a problem

Question 12

shifts in animal biomass

Answer 12

livestock now vastly out weigh all wild mammals

Question 13

Eutrophication

Answer 13

around half of fertilizer is not taken up by crops
- excess nutrients cause algal blooms growth of parasites
- human health issues

Question 14

Pesticides

Answer 14

• many pesticides do not break down, and are magnified up the food chain

Question 15

Erosion

Answer 15

• heavy grazing, ploughing break up soil aggregates and remove stabilising vegetation
• loss of top soil
• depletes soil carbon stocks

Question 16

Hydrology

Answer 16

• damns and aquifer depletion majorly reshaping hydrology
• water likely to be a major driver of international conflicts in the decades to come
• ex. Colardo river

Question 17

Salinization

Answer 17

-uplift of water from deep basins has brought subsurface salts to the surface, land now very inhospitable

Question 18

How did agriculture change human society

Answer 18

• allowed permanent settlements: affected almost all aspects of society and the economy!
• greater amounts of food, support of non-producers, specialization and division of labour, sedentism, great population density

Question 19

Issues with agriculture

Answer 19

• brought: disease, land ownership, land degradation
• highly labour-intensive
• driver of mechanization
• led to a decline in general and oral health
• more zoonotic diseases
• communicable diseases

Question 20

Preserving the gene pool

Answer 20

• svalbard global seed vault
• dug into an arctic hillside, the vault contains almost a million samples from the genetic diversity of crops from all over the world