Conservation Biology and Global Change: Chapter 56

Conservation Biology seeks to preserve life, it integreates: Ecology, Physiology, Molecular biology, Genetics, Evolutionary Biology

Restoration Ecology applies ecological principles to return degraded ecosystems to their natural state.

Humans threaten Earth's biodiversity

  • Over 1.8 million species have been named, but 10-200 million are estimated to exist and humans are pushing many towards extinction.external image 56_03BiodiversityLevels-L.jpg
  • Levels of biodiversity:
    1. Genetic Diversity - comprises genetic variation within and between populations
    2. Species Diversity - the variety of species throughout the biosphere or within an ecosystem
      • Endangered species are those "in danger of becoming extinct through out all or a significant portion of its rang."
      • Threatened species are those likely to become endangered in the near future.
      • Conservation biologists are concerned with extinction since globally 12% of birds, 20% of mammals, and 32% of amphibians are threatened with extinction.
    3. Ecosystem Diversity - variation of the biospheres ecosystems.
      • Reduced by human activity
      • Ex: <50% of wetlands have been drained and converted to other ecosystems
  • Humans should care about biodiversity because of biophilia, which is our sense of connection to nature and all life.
    • Benefits of Species and Genetic Diversity
      • Many threatened species could provide food, fibers, and medicine for human use.
        • 25% of prescription are derived from plants
      • The loss of a species means losing genes. These genes could code for useful proteins that could be used in medicine, foods, and products.
    • Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life.
      • Air and water purification
      • Detoxification and decomposition of waste
      • Cycling of nutrients
      • Moderation of extreme weather
  • There are four major threats to biodiversity
    1. Habitat destruction
      • Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere.
      • Brought about by: agriculture, urban development, forestry, mining, and pollution.
      • Habitat fragmentation and destruction leads to a loss of biodiversity.
        • IUCN implicates destruction of habitats for 73% of species extinctions.
        • 98% of tropical dry forest in Mexio and Central America has been cut down
        • 90% of tropical rain forest has been cut down
        • 93% of coral reefs have been harmed
    2. Introduced species are those that humans move from native locations to new geographic regions.
      • Without predators, parasites, and pathogens the introduced species can rapidly spread.
      • Disrupt the new community
      • Can be introduced by accident if the plant seed or animal gets onto a ship/plane and gets carried to another place.
      • Can be introduced on purpose with good intentions and then have bad effects.
    3. Overexploitation is human harvesting of wild plants/animals at rates exceeding the ability of those species populations to rebound.
      • In the fishing industry many game fish populations have been greatly reduced.
      • DNA can help conservation biologists identify the source of illegally obtained animal products.
    4. Global change is alterations in the fabric of Earth's ecosystems at regional to global scales.
      • Changes in the atmosphere chemistry, climate, etc

Population conservation focuses on population size, genetic diversity, and critical habitat

  • Follow two main approaches:external image extinction_vortex_diagram.jpg
    1. Small-population approach: studies processes that can make small populations become extinct.
      • Small populations are vulnerable to inbreeding and genetic drift which draws the population down an extinction vortex to smaller and smaller population size until there are no surviving individuals.
        • The Greater Prairie Chicken and the Extinction Vortex case study showed that the declining population rebounded, confirming that it had been on its way to extinction due to low genetic variation but the transfusion of genetic variation saved them.
      • Minimum viable population (MVP) is the minimum population size at which a species can survive.
        • Depends on factors that affect a population's chances for survival over time.
      • Effective population size is based on the population's breeding potential and helps determine a meaningful estimate of MVP.
        • Effective size = 4(number males x number females)/(number males + number females)

        • First tests of this was on grizzly bears
    1. Declining-population approach
      • Focuses on threatened and endangered populations that show a downward trend.
      • Emphasizes the environmental factors that caused a population to decline.
      • Steps for Analysis and Intervention
        1. Confirm that population is in decline
        2. Study species natural history
        3. Develop hypotheses of all possible causes of decline
        4. Test the hypothesis in order of likeliness
        5. Apply results to manage the species and monitor its recovery
  • Weighing Conflicting Demands
    • Species conversations requires resolving conflicts between habitat needs and human demands.
    • Managing habitat for one species may have an affect (positive or negative) on other species.

Landscape and regional conservation help sustain biodiversity

  • Seeks to make biodiversity conservation a part of land-use planning.
  • Landscape structure can influence biodiversity.
    • Fragmentation and Edges
      • Edges (boundaries) between ecosystems are defining features of landscapes.
      • Certain species take advantage of edge communities to access resources from both adjacent areas.
      • The Biological Dynamics of Forest Fragments Project found that landscapes dominated by fragmented habitats support fewer species due to a loss of species adapted to habitat interiors.
    • Corridors that connect habitat fragments
      • A movement corridor is a narrow strip of quality habitat connecting otherwise isolated patches.
        • Promote dispersal and help sustain populations
        • Sometimes are human constructed
  • Establishing Protected Areas
    • Apply understanding of ecological dynamics to protect areas and slow the loss of biodiversity. Focus on hot spots of diversity.
    • A biodiversity hot spot is a small area with a great concentration of endemic species and endangered and threatened species.
      • Good choices for nature reserves.

external image 55_17BiodiversityHotSpots_L.jpg

  • Nature reserves are biodiversity island in a sea of habitat degraded by human activity.
  • Must consider disturbances as a functional component of all ecosystems.
    • Large reserves may be better since large, far-ranging animals with low-density populations require extensive habitats.
    • Small reserves are more realists and may slow the spread of disease throughout a population.
  • A zoned reserve is a extensive region that includes areas relatively undisturbed by humans surrounded by areas that have been changed by human activity.
    • Used for economic gain
    • Known as conservation areas

Earth is changing rapidly as a result of human actions

external image 54_23BiomagnificationPCB.jpg
  • Nutrient Enrichment
    • Humans transport and add new materials (including toxins) to ecosystems.
    • Agriculture leads to the depletion of nutrients in the soil.
    • Fertilizers add nitrogen to the ecosystem.
    • Critical load is the amount of added nutrient that can be absorbed by plants without damaging the integrity of the ecosystem.
    • Runoff and sewage from agriculture leads to phytoplankton blooms in the Atlantic Ocean. When these blooms decompose "dead zones" occur due to low oxygen levels.
  • Toxins in the Environment
    • Humans release toxic chemicals that were previously unknown by nature.
    • Harmful substances can last for long periods of time in an ecosystem.
    • Biological magnification concentrates toxins at higher trophic levels where biomass is lower.
      • PCBs and pesticides are subject to biological magnification
      • Ex: herring gulls of the Great Lakes lay eggs with PCB levels 5,00 time greater than in phytoplankton.
  • Greenhouse Gases and Global Warming
    • Burning fossil fuels and things such as deforestation cause carbon dioxide levels in the atmosphere to increase.
    • The greenhouse effect is when carbon dioxide, water vapor, and other greenhouse gases reflect infrared radiation back towards Earth.
      • Affects Earth's surface temperature
      • Affects distribution of precipitation
    • Global warming can be slowed by reducing energy needs and converting to renewable sources of energy.
      • Will take an international effort
  • Depletion of Atmospheric Ozone
    • A layer of ozone molecules in the atmosphere protects Earth from the damaging effects of UV radiation.external image depletion2.gif
    • Satellite studies showed that ozone has been thinning since the 1970s.
    • Ozone destruction is mainly a result of chlorofluorocarbons (CFCs) produced by humans.
      • CFCs contain chlorine which react with ozone and makes oxygen, this is what causes ozone to thin.
    • Ozone depletion causes DNA damage to plants and poor phytoplankton growth. In humans in can cause skin caner.

Sustainable development can improve human lives while conserving biodiversity

  • Helps to establish long-term conservation priorities.
  • Sustainable Biosphere Initiative
    • Sustainable development is development that meets the needs of people without limiting the ability of future generations to meet their needs.
    • Sustainable Biosphere Initiative: goal is to define and acquire basic ecological information for responsible development, management, and conservation of Earth's resources.
    • Connects life sciences, social sciences, economics, and humanities.
  • The Future of the Biosphere
    • Modern lives differ from lives of early humans. Our behaviors reflects remnants of our ancestral attachment to nature and the diversity of life - concept of biophilia.
    • The sense of connection to nature could motivate realignment of environmental priorities. By understanding the processes and diversity of life, we become more aware of ourselves and our place in the biosphere.

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