Biodiversity is understood at three levels: genes・species・ecosystems, and it is the foundation of the ecosystem services that support human society.
Basic Knowledge
Three levels of biodiversity: ① genetic diversity(diversity of genes within a species)② species diversity(richness of species in an area)③ ecosystem diversity(tropical forests・coral reefs・wetlands, and so on).
Four threats to biodiversity: ① destruction・fragmentation of habitats② overhunting・overharvesting③ introduction of invasive species(examples: largemouth bass・raccoons)④ environmental pollution・global warming. The current rate of extinction is 100〜1000 times the natural extinction rate.
Ecosystem services(MA classification): provisioning services(food・water・timber)・regulating services(climate regulation・flood prevention)・cultural services(recreation)・supporting services(soil formation・nutrient cycling).
Conservation efforts: national parks・ecological corridors・Washington Convention(CITES=international regulation of trade in endangered species)・Convention on Biological Diversity(CBD, Rio 1992).
Explain the mechanisms by which invasive species threaten native species from the viewpoints of competition・predation・disease.
Answer: ① Competition: an invasive species overlaps its niche with that of a native species and competitively excludes it. ② Predation: native species rapidly decline because they have not evolved defensive behaviors against the invasive predator. ③ Disease: native species die from infection because they have no immunity to pathogens carried by the invasive species.
- Three levels of biodiversity=genes・species・ecosystems
- Current extinction rate=100〜1000 times the natural rate
- Four threats=habitat destruction・overhunting・invasive species・environmental pollution
- Ecosystem services=provisioning・regulating・cultural・supporting
- Washington Convention=international regulation of trade in endangered species
- Convention on Biological Diversity(CBD)=Rio de Janeiro, 1992
- Ecological corridor=green passage connecting fragmented habitats
Points to Note
① Small populations with low genetic diversity face increased extinction risk because of the bottleneck effect・inbreeding. ② The Washington Convention(CITES) regulates trade, while the Convention on Biological Diversity(CBD) has three goals: conservation・sustainable use・fair sharing of benefits. ③ Fungi(mushrooms・molds・yeasts) are eukaryotic organisms that are not plants and are more closely related to animals.
Practice
- State all three levels of biodiversity.
- Of the four threats to biodiversity, name three that are directly caused by human activities.
- Explain the four types of ecosystem services and give one specific example of each.