Conservation

  • Biodiversity: scientists name/described 1.8 million species; about 10-100 million on earth; humans rapidly pushing many species to extinction; conservation biology seeks to preserve life/integrating several fields to preserve biodiversity
  • Types of diversity 
    • Genetic diversity comprises gen. Variation within population/between population
    • Species diversity is variety of species
    • Endangered: in danger of becoming extinct
    • Threatened: likely to become endangered soon
    • Local extinction is extirpation (loss in one area but can be repopulated)
    • Ecosystem diversity (variety of ecosystems)
    • Human activity reducing ecosystem diversity (>50% wetlands in U.S. drained/converted to other ecosystems)
  • Benefits of biodiversity
    • Ecosystem services: ways natural ecosystems/species help sustain human life
    • air/H2O purification, detoxification and decomposition, nutrient cycling, moderation of weather extremes 
  • Threats to biodiversity
    • Habitat loss: greatest threat to biodiversity (habitat fragmentation/destruction leads to loss of biodiversity)
    • Introduced species (those that humans move to new geographic regions); spread rapidly, competition exclusion (try to occupy same niche)
    • Overharvesting: human harvesting plants/animals @ rates exceeding ability of populations of those speeis to rebound (K-selected species are especially vulnerable)
    • Global change: alterations in climate, atmospheric chemistry, broad ecological systems (reduces the capacity of earth to sustain life)
  • Population conservation
    • Small population approach: Small populations are vulnerable to interbreeding/genetic drift (extinction vortex) -> diverse alleles
    • Minimum viable population (MVP): min. Pop. size @ which species can survive
    • MVP -> factors affecting population’s chances for survival over particular time
  • Declining-population approach: focus on threatened/endangered populations that show downward trend; emphasizes environ. Factors causing pop. to decline 
  • Conflicting demands: Society vs biodiversity conservation (managing habitat for 1 species might have +/- effects on other species--complex interconnection); big brown eyes effect--cuteness; ecological role of species (which species are most important/keystone) 
  • Human actions are changing the earth
  • Nutrient enrichment: human activity removes nutrients from 1 part of biosphere and adds them to another
    • Agriculture leads to depletion of nutrients in soil, fertilizers = nitrogen/phosphorus/potassium (NPK)
    • Runoff into water = algal blooms -> eutrophication; non-points source pollution
  • Toxins in the environment: biological magnification concentrated toxins @ high trophic levels where biomass is lower; pharmaceutical drugs/estrogen/mercury 
    • Ex: animal eats plant with pesticides and passes toxin to other predators
  • Greenhouse gases: rising level of CO2/other greenhouse gases in atmosphere 
  • Landscape ecology: study of how spatial arrangement of habitat types affects distribution/abundance of organisms/ecosystem processes 
    • Landscape: area containing several different ecosystems 
    • Ecotone: where 2 habitats meet (forest/garden)
    • Edges: boundaries between habitats (small-scale ecotones) 
  • Establishing protected areas
    • Movement corridor: narrow strip of habitat connecting otherwise isolated patches
    • Promotes dispersal, sustain populations (genes flow), can spread disease
    • Biodiversity hotspots: high concentration of endangered/threatened species
    • Nature reserves: must consider disturbances as functional components of all ecosystems-fire dependent
    • Urban ecology: balances species preservation with needs of people (like Central Park)
    • Fewer larger reserves/more small reserves (best choice depends on species)