L18 - Agriculture Flashcards
Define domestication
A change in the gene pool of a plant or animal resulting from a coevolutionary process
How does domestication occur?
- Artificial selection: humans manipulate plant or animal breeding to selectively develop phenotypic traits by choosing which males and females will reproduce (reproduction in a controlled environment)
What is Belyaev’s farm fox experiments?
- 40-year long experiment in tamability
- Goal was to breed foxes with a “friendly” behaviour
- Result: heritable behavioural and morphological changes associated with hormone levels
What kinds of characteristics are selected for animals to survive farm conditions?
- Ability to survive stress (crowded conditions, caging, de-beaking)
- High production
- Ability to survive food outside their natural diet
- Disease resistance (but also heavy reliance on anti-parasitics, antibiotics)
What is the Green Revolution?
- Began in mid-20th century
- Primary goal: to combat world hunger by increasing food production in countries with growing populations and limited resources
- Particularly successful in Asia and Latin America.
How did the Green Revolution increase food production?
- Selection of Dwarf crop varieties (higher tolerance for certain conditions - e.g, drought)
- Selection of high-yielding crop varieties
- Increased irrigation
- Increased mechanization
- Agrochemicals and synthetic fertilizers
- Consolidation of land - larger farms
What are some characteristics of polyculture?
- Annual/perennial mix - self seeding
- Diverse structure
- Large insect/animal community (pollination)
- Diversity of plant traits
- Evolutionary processes occurring
What are some characteristics of monoculture?
- Annual only
- Homogeneous structure
- Few insects/animals
- Specific plant traits adapted to narrow conditions
- No gene flow, and thus no evolutionary processes
Which traits are selected for today in plants?
- 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 (protein content, flavour, etc.)
- Storage quality
What are GMOs?
- Organisms 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
What are the consequences of increased use of antibiotics in agriculture?
- Used in agriculture for increasing yield and enabling high density
- Giving healthy animals antibiotics to prevent disease gives rise to antibiotic resistant bacteria
- Antibiotic-resistant bacteria can be transferred to humans: consumption, human contact, waste runoff, transportation & processing
What are some specific ways that agriculture has changed the planet?
- Distribution of biomass
- Deforestation/ecosystem displacement
- Greenhouse gas emissions
- Eutrophication (nutrient enrichment)
- Soil erosion
- Freshwater depletion and salinization
- Biodiversity reduction (pesticides, invasive species, habitat removal)
How does agriculture cause ecosystem displacement/fragmentation?
- 37% of earth = agriculture use
- Removal of entire tracts of ecosystem (forests (deforestation), prairies)
How has agriculture created shifts in animal biomass?
Livestock now vastly outweigh all wild mammals (83% of which are gone)
How does agriculture promote eutrophication?
- Increase in synthetic nitrogen fertilizer since the Green Revolution
- Around 50% of fertilizer is not taken up by crops
- Instead, enters air or water
- Excess nutrients cause algal blooms, growth of parasites, fish kills - MAJOR DEAD ZONES
