Lecture 18-20 Flashcards
When did food productions begin in human civilization?
Food production = deliberate raising of animals and cultivation of cereal grasses and edible root plants
12 000 years ago
What is domestication?
A change in the gene pool of a plant or animal resulting from a coevolutionary process
Example: wolves –> dogs
How can domestication occur?
Through artificial selection: humans manipulate plant/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 envr
What kind of traits are being selected in modern days to survive farm conditions?
Ability to survive stress (de-beaking, crowded conditions, caging)
High production (egg, meat, milk)
Ability to survive food (e.g. cows fed corn –> not their natural diet)
Can select for disease resistance but also increased reliance on anti-parasitics, antibiotics, etc. to control disease caused by conditions
Which traits are selected for today in plants?
Resistance to herbicides
Production of non-viable seed (so farmers dependent on yearly seed purchases)
Uniform germination and maturation times (so they can all be harvested at once)
Unifrom grain size
Disease and pest resistance
High yield
Herbicide tolerance
Food quality (protein content, flavour, etc.)
Storage quality
What is the result to modern day selection in plants?
Only the highest yield plants and animals persist to retain financial solvency
Many plant species are genetically identical
Only the highest yield species persist
How are modern crops experiencing genetic bottleneck?
Crop plants are often extensively inbred and not allowed to reproduce sexually in the field, severly limiting their gene pool and reducing variation needed to adapt (e.g. to climate change)
What percentage of canola growth in Canada is GMO?
95%
How many GMO food crops are sold in Canada?
9
What are GMO?
Genetically modified organism
Creates combination of plant, animal, bacteria and virus genes that do not occur in nature or through traditional crossbreeding methods
Traits added: herbicide resistance (weed control), pest resistance, reduced browning
Are GMOs a short-circuit of evolution?
Actually, genges move between kingdoms in nature quite regularly
But there is potential for hybridization
What is the result of rapid evolution of antibiotics?
Antibiotic use is widespread in agriculture for increasing yield and enabling high density
This results in rapid resistance, significant concerns about loss of effectiveness and spread
Superbugs can arise, resistance to pesticides
What are some specific ways that agriculture has changed the planet?
Ecosystem displacement/fragmentation
Source of CO2, NOx and CH4
Shifts in animal biomass (livestock now vastly outweigh all wild mammals)
Eutrophication (nutrient enrichment)
Pesticide bioaccumulation
Erosion
Freshwater depletion
Salinization
–> all of these changes modify the selection pressures, gene flow and genetic diversity of populations
What are the impacts of ecosystem displacement/fragmentation?
37% of earth is now used for agriculture of some kind (the only two large areas that aren’t are the world’s two largest rainforests that are under significant threat)
Removal of entire tracts of ecosystem
Agriculture land use is a huge driver of deforestation (causes drought, fire, disease)
What are the impacts of agriculture of GHG emissions?
Come from enteric fermentation (livestock), manure, fertilizer, rice paddies
Agriculture management (tillage, grazing) also cuases loss of stored C in soils
Clearing peatland/wetlands also increase CO2 emissions a lot
What is the impact of agriculture on eutrophication?
A lot of fertilizer runoff from agriculture (contains N and P runoff)
Goes into air or water
Excess nurients causes algal blooms, growth of parasites, kills fish
Human health issues
What are the impacts of pesticides?
Many pesticides do not break down, and are magnified up the food chain (bioaccumulation)
Many non-target effects (DDT on bird eggs, fish kills)
What is the impact of erosion?
Heavy grazing, ploughing break up soil aggregates and remove stabilizing vegetation
Result can be massive loss of topsoil
Depletes soil carbon stocks
How is freshwater impacted by agriculture?
Agriculture is majorly reshaping hydrology via dams and aquifer depletion
Water likely to be a major dirver of international conflict in the decades to come
Ex. the colorado river –> now rarely reaches the sea, every last drop of its water fully overallocated, no delta habitat (pop. of fish, shrimp, and sea mammals have seen dramatic decline)
What are the impacts of salinization?
Uplift of water from deep basins has brought subsurface salts to the surface
Land now very inhospitable since high salt content prevents vegetation growth
How has agriculture changed human society?
Allowed permanent settlements: affected almost all aspects of society and the economy
Greater amounts of food, more reliable
Storage: delayed-return rather than immediate return
Support of non-producers
- specialization and division of labour
Sedentism (staying in one place)
Great pop. density
–> this all lead to disease, land ownership, land degradation
How has agriculture changed our bodies?
The advent of agriculture lead to a decline in general and oral health due to an increase in carbohydrates, softer calorie-dense foods, reduced diet variety
- This lead to reduced skeletal robustness, shorter stature, smaller jaw, dental decay and malocclusion
Small mobile populations gave way to large settlements, with close proximity of humans and animals. Sanitation was poor
- Zoonotic diseases: influenza, smallpox, measles, tuberculosis
- Communicable diseases: the above, plus things like cholera
Evidence for changes in areas of the genome associated with immunity, lactose tolerance, digestion, pigmentation
What are some ways to improve agriculture going forward?
Preserving the gene pool
Agroecology
What are the main 5 global drivers of change?
Climate change
Habitat loss
Overexploitation
Pollution
Invasive species
What are invasive species?
A non-indigenous species whose introduction does or is likely to cause economic or environmental harm or harm to human health
Causes damages by changing biotic interactions
What is the societal relevance of invasive species?
Major cause of biodiversity loss, physical changes, industrial impacts (economic cost), aesthetics (defoliated forest), property values
What are the 5 processes of a species invasion?
Source location of species
Transport/introduction
Establishment
Spread
Impact
What are some examples of pathways of invasion?
On purpose: commerce in living organisms, aesthetics, food, livestock, pets, biological control, etc.
Transport related: shipping cargo, travelers in baggage, in wood, on planes/boats, ballast water, canals, etc.
The more number
What are some common traits of invasive species?
Generalists (eating a lot of thigns), high tolerance for different environmental conditions, phenotype variations
What are common traits of invaded ecosystems?
Islands/lakes –> relationship between diversity and size
Smaller areas
How were zebra mussels introduced? What are their impacts?
Introduced through ballast water discharge
They invade pipes, and suffocate other mussels/organisms
How do invasive grasses promote a positive feedback loop?
Introduction of highly flammable plants increase wildire risk –> more fires –> envr becomes more dry –> drier environments are more prone to fires –> promotes the growth of invasive species
What are general policies/management options for each process of an invasion?
Species in pathway: prevention – > reduce species in pathways, institute risk screening
Transport: early detection, rapid response –> monitor for early invasions
Establishment: eradication –> provide authority and funding for eradication and control programs
Spread: control and slow the spread –> fund slow-the-spread programs
Ecological, human health, or economic impact: human adaptation (change behaviour and bear the costs) –> establish national center for invaisce species management
What are 4 screening questions that can be used to evaluate invasive species?
Is the spcies adapted for aquaculture or ornamental purposes?
Has the species become naturalized where introduced?
Does the spcies have invasive races/varietes/sub-species?
Is the species reproductive tolerance suited to climates in the risk assessment area?
What are some ways to control pest management?
Manual (traps)
Chemical (herbicides, pesticides)
Biological (natural predators/parasites)
Genetics, mRNA
What is biodiversity?
The variability of life on Earth
The variability among living organisms from all sources including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems
How does habitat change/loss impact biodiversity?
Decreases population sizes –> more vulnerable to extirpation
What are some factors that are participating in biodiversity loss?
Pollution
Invasive species
Cliamte change
Overexploitation
Habitat loss
Why should we care about biodiversity loss?
Ethics/value of life
Medical
Ecosystem services
- direct (resources such as food)
- indirect (envr. modification, coral reefs)
- lifestyle (recreation)
Culture
Break down total economic value in use value and non-use value
Use value:
- Direct use value: provisioning services, cultural services
- Indirect use value: regulating and supporting services
Non-use value: provisioning, cultural, regulating and supporting services
- Existence value
- Option value
- Bequest value
What are some examples of ecosystem services?
Provision of food, fuel and fibre
Provision of shelter and building materials
Purification of air and water
Detoxification of air and water
Stabilization/moderation of climate
Moderation of floods, droughts, temp. extremes, and forces of wind
Generation and renewal of soil fertility, including nutrient cycling
Pollination of plants
Control os pests/diseases
Cultura/aesthetic benefits
etc……
What are the consequences of ecosystem services?
Promotes the protection of only certain biota
For instance, only 15 plants and 8 animal species supply 90% of our food
Yet biodiversity is about variations
How is diversity (species richness) related to biomass? Niche Complementary hypothesis
More diversity (not overlapping) increases biomass
However, overlap in niches that they occupy leads to no additional benefit to biomass (biodiversity richness)
- redundacy leads to stability in biomass
Therefore, positive but saturating relation between diversity and biomass (diversity can affect productivity)
Is a simple ecosystem with few species at each trophic level better than an ecosystem with multiple species?
In the 50s and 60s it was believed that the more pathways there are, the less severe the failure of any one pathway
In the 70s and 80s, it was believed that the more complex systems were less stable
Now, we believe that it depends upon the type of interaction and the strength of the interaction –> it is more nuanced
What is the spatial insurance hypothesis?
Local diversity may be maintained by immigration from the region which provides the source of variation (species or genetic diversity) that can buffer ecosystem processes against environmental variation
- ability to recover because of the diversity in a spatial context
If many sites are considered (as in a metapopulation) then differences in the timing of biomass fluctations can average out across space; a form of regional stability
What happens to number of pests as biodiversity increases?
It decreases
What are some sources of uncertainty for the links between species richness and ecosystem services?
Mismatch between functions measured and final ecosystem service
Mismatch between the study conditions and actual management conditions and service delivery to society
Studies insufficiently comprehensive to assess the different processes underpinning ecosystem-service supply
Simultaneous effects of different components of biodiversity (richness, composition, functional diversity)
Confounding environmental factors other than richness that contribute to effects on service supply
Trade-offs between positive and negative effects of richness of the various functions underpinning service supply
Context-dependent patterns
What are some issues with the Endangered Species Act?
There is an increasing number of species listed, however it is unclear whether newly listed = newly endangered
Also few removed, unclear whether extinctions, errors, recovered
