L20 - Biodiversity Flashcards
How many species have been identified currently?
- 1.75 M identified
- 8.7 M estimated
- Estimates have ranged 3M-100M
What are drivers of species extinction?
- Habitat loss
- Population size related to the probability of local extirpation
- Overexploitation
- With a growing population, have arguably overexploited a lot of these resources
- Pollution
- Eutrophication leads to algal blooms and then dead zones & fish kills
- Climate change
- Species’ homes being destructed faster than they can adjust
- Species moving to areas they are not well adapted to (Polar bears moving south)
- Invasive species
- New predators can wipe out entire populations
Biodiversity loss:
- ~900 species have gone extinct in the last 500 years
- ~ 400/50 000 vertebrate since 1900
- 10 000- 100 000 species lost per year?
- 1M species at risk (IPBES 2019)
- Potentially orders of magnitude beyond background rate
- Potentially changes in abundance before extinction
Why should we care about biodiversity loss?
- The way our planet works relies on biodiversity
- Ecosystem services provided by biodiversity
- Direct: resources (e.g., food)
- Indirect: environmental modification
- Lifestyle: recreation
- Ethics: Intrinsic value of biodiversity (beyond their services provided to humans)
- Culture
- Livelihood: many countries are economically dependent on these different species
- Medicinal discoveries from plants
Medicinal properties of plants?
- Drug vincritine to treat leukemia
from rare Rosy Periwinkle - Taxol for ovarian cancer from
- Pacific Yew tree
Food resources?
- Wheat
- Soy
- Cattle
Culture?
- Hunting & fishing
- Beaver, salmon - species significant to a nation/culture
Indirect services
- Climate control
- Physical stability (coral reefs)
- Recreation
Economic valuations?
- Use value: direct use value
- Consumptive use value: provisioning services
- Non-consumptive use value: cultural services
- Indirect use value:
- Regulating services, supporting services
- Non-use value:
- Existence value
- Option value
- Bequest value
- Provision, cultural, regulating, supporting services…
Examples of ecosystem services?
- Provision of food, fuel and fibre
- Provision of shelter and building materials
- Purification of air and water
- Detoxification and decomposition of wastes
- Stabilization and moderation of the Earth’s climate
- Moderation of floods, droughts, temperature extremes and the forces of wind
- Generation and renewal of soil fertility, including nutrient cycling
- Pollination of plants, including many crops
- Control of pests and diseases
- Maintenance of genetic resources as key inputs to crop varieties and livestock
breeds, medicines, and other products - Cultural and aesthetic benefits
- Ability to adapt to change
What species (types) play a role?
- Predominantly plants !!!!
- Some species of animals
- Specific types of organisms and species that provide these ecosystem services, not just “biodiversity” at large
What is the niche complementarity hypothesis?
Differences between species in their functional traits (feeding habits, spatial distribution, and reproductive strategies) will enhance ecosystem functioning by allowing greater complementarity in resource use between species (avoiding direct competition with each other)
Which ecosystem is “better”? More stable? For which should we spend resources to conserve?
- 50s & 60s: the one with more interactions
- The more pathways there are, the less severe the failure of any one pathway.
- 70s & 80s: more complex systems (higher biodiversity) are the least stable
- more pathways/opportunities of failure
- Current: depends on the types of interactions
Species environment interactions: redundancy & stability
- Improved stability with increasing diversity:
- Portfolio effect/Statistical Averaging
- Sum of many random fluctuations will average out to produce a more stable ensemble
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.
