9.10 - Human Threats to Biodiversity

Question 1

HIPPCO

Answer 1

• Habitat Fragmentation/loss: Deforestation (lumber, cities, roads) Wetland draining (ag, urbanization) River water level decreased by dams
• Invasive Species: Invasives such as z. mussel and kudzu vine outcompete native species for food/space, lowering populations
• Population Growth: Human pop. growth drives hab. loss, Urbanization, ag. expansion to feed more people remove/fragment hab.
• Pollution/Pollutants: Oil spills reduce marine org. pop. sizes, Pesticides (glyphosate, atrazine) kill non-target species
• Climate Change: Shifts biomes & therefore species habitat ranges, can change temp. & precip. patterns too rapidly for a species to adapt or migrate, causing pop. decline or extinction
• Over Exploitation: Excessive hunting or poaching (faster than reproductive rate) leads to pop. decline & potential extinction

Question 2

Habitat Fragmentation

Answer 2

• Habitat Fragmentation: Breaking of larger, continuous habitats into smaller, isolated patches; disrupts breeding, hunting, migration
• Roads and Pipelines: Roads & oil/gas pipelines fragment habitats; disrupt movement & lead to fatal collisions with vehicles
• Ag and urban land use: Clearing forest/grassland for ag. fields or urbanization fragments those habitats.
• Logging: Both removal of trees & construction of logging roads to transport lumber fragment forest ecosystems

Question 3

Metapopulations

Answer 3

• Some species are more disrupted by fragmentation than others
  - Large predators needing large hunting space
  - Smaller populations of large k-selected mammals may struggle to find mates
• Habitat Fragmentation creates smaller, isolated subpopulations
• Smaller subpopulations have less genetic diversity, are more prone to inbreeding depression, and are less resilient to env. disturbance or disease
• Metapopulations are mostly isolated, subpopulations connected by habitat corridors; this can allow some gene flow (mating between populations) and improve genetic diversity

Question 4

Edge Effect

Answer 4

• “Edge habitat” where two ecosystems such as forest-grassland or ocean-river (estuaries) meet have diff. characteristics than the middle of each ecosystem
• Some species thrive in the edge habitat & biodiversity is often higher in edge habitats due to diversity of food, shelter, and nutrient resources
• Edge habitats can expand range of potentially disruptive species (ex: brown headed cowbird) that thrive in grassland-forest edge
• Brood parasite that leaves its eggs in the nests of songbirds for them to raise, unknowingly

Question 5

Climate Change

Answer 5

• Climate change can shift the range of habitats, or increase/decrease their range altogether
• Temperature Change: Warming temp. can shift biomes
  - Boreal forest & temperate coniferous forests may shift northward; tundra may decrease
• Precipitation Change: Warming global. temp. will decrease precipitation in some areas, leading to soil desiccation and desertification
  - Will increase in some areas, expanding tropical ecosystems
• Sea Level Rise: Estuary habitats (salt marshes, mangroves) become fully submerged & more saline; coastal ecosystems become flooded

Question 6

Biodiversity ad Domestication

Answer 6

• Domestication of species for agriculture generally decreases genetic and species biodiversity

Crops:
- Fewer plant species are grown as selective breeding and GM results in only the highest yield species
- GM use and selective breeding also lead to less genetic diversity in crops, making them more vulnerable to disease or environmental disruptions

Livestock:
- Historically, there have been over 8,000 breeds of the 11 species most commonly eaten by humans
- Breeds were uniquely adapted to local climate
- Many breeds are now extinct, or at risk due to selection for only highest productivity

Question 7

Mitigating Biodiversity Loss

Answer 7

Protecting and Connecting Habitats:
- Protecting important habitats by creating national parks, nature preserves, or preventing them from being developed
- Connecting fragmented habitats with wildlife corridors enables movement/breeding

Sustainable Land Use:
- Urban growth boundaries, infill, and building up (not out) to reduce urban sprawl can preserve existing habitats
- Expanding parks, urban gardens, green roofs can provide habitat for many species
- Sustainable agriculture, lowering meat consumption can reduce ag. land needs, preventing hab. loss

Restoring Lost Habitats:
- Replanting clear-cut forests
- Reestablishing prairies on old ag. fields or golf courses