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Chapter 55

Chapter 55. Conservation Biology & Restoration Ecology. Human Activities threaten Earth’s Biodiversity. Approximately 50% of land surface on earth has been altered by humans The same holds true with freshwater.

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Chapter 55

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  1. Chapter 55 Conservation Biology & Restoration Ecology

  2. Human Activities threaten Earth’s Biodiversity • Approximately 50% of land surface on earth has been altered by humans • The same holds true with freshwater. • It is estimated that the rate of extinction of species is greater than any time on earth. • While extinctions do naturally occur, it is the current rate of extinctions which cause scientists to become alarmed.

  3. Restoration ecology applies ecological principles • An effort to return degraded ecosystems to conditions similar as possible to their natural state • Throughout the biosphere, human activities are altering ecosystem processes on which we and other species depend • We are dependent on other organisms, the environment; the biosphere!!

  4. The Three Levels of Biodiversity • Biodiversity has three main components • Genetic diversity • Species diversity • Ecosystem diversity

  5. Genetic Diversity • Genetic diversity comprises • The genetic variation within a population • The genetic variation between populations

  6. Species Diversity • Is the variety of species in an ecosystem or throughout the biosphere • Greater species diversity = a healthier ecosystem • An endangered species is one that is in danger of becoming extinct throughout its range • Threatened species are those considered likely to become endangered in the future

  7. Conservation biologists are concerned about species loss Threatened with extinction Extinction status • 12% of known species of birds • 24% of mammals • 200 plant species in U.S. have become extinct since records have been kept • 20% of known freshwater fishes are now extinct or threatened • 32% all known amphibian species are either extinct or endangered • If current rates of extinction hold true, >1/2 plant & animal species will be gone by end of this century!

  8. Ecosystem diversity • Identifies the variety of ecosystems in the biosphere • Is being affected by human activity • >50% wetlands in U.S. have been drained and converted into other ecosystems • About 90% of native riparian communities in CA, AZ and NM have been destroyed by overgrazing, flood control, water diversion and invasive plants

  9. Benefits of Species & Genetic Diversity • Humans feel a sense of connection to nature & other forms of life (Biophilia) • We benefit from biotechnology such as pharmaceuticals generated from plants • (Bioprosepecting) where corporations are currently trying out new ways to use genes to develop new medicines, foods, petroleum substitutes…

  10. Ecosystem Services • Entire ecosystems also benefit humans. Ecosystems: • Purify our air & water • Reduce severity of droughts and floods • Generate & preserve fertile soils • Detoxifies & Decomposes waste • Pollinates crops, Disperses Seeds • Controls pests that threaten our crops • Moderates weather extremes

  11. 4 major threats to Biodiversity • Habitat destruction • Introduced species • Overexploitation • Disruption of “interaction networks”

  12. Habitat Destruction • Is the single greatest threat to biodiversity • Includes habitat fragmentation

  13. Introduced Species • Are those that humans move from native locations to new geographic regions • Usually disrupt their adopted community • ex. Zebra mussels

  14. Overexploitation • Harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound • Ex. Fishing industry/North Atlantic Bluefin Tuna now less than 20% of its population in 1980 • Elehants, whales and rhinos are vulnerable due to low repro. rates

  15. Population conservation • Focuses on: • Population size, genetic variability & critical habitat • May lead to The Extinction Vortex, where small populations lose genetic variability due to inbreeding. • This may lead to extinction as the population loses its ability to reproduce successfully • Not all populations are affected this way…depends on the species.

  16. Minimum Viable Population Size (MVP) • The minimum population size at which a species is able to sustain its numbers & survive • Effective Population Size is an estimate of MVP • Population viability analysis (PVA) • Predicts a population’s chances for survival over a particular time.

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