1.5: Biodiversity

the three types of biodiversity

• species diversity/species richness: the number of species in a region
• genetic diversity: the variety of genes among individuals in a species
• ecosystem diversity: the richness and complexity of a biological community
  • eg. # of niches, # of trophic levels, etc.
• extinction: the process of a species completely dying out, complete when its last member dies
  • we are in the middle of the sixth mass extinction, the first to be caused by a single species (humans)
  • this mass extinction is occurring within decades, not millions of years
  • in many cases, there is no space for species recovery as habitats are being eliminated.

the importance of biodiversity

biodiversity provides us with

• food
• products of economic value
• drugs and medicines
  • eg. vinblastine and vincristine — chemotherapy drugs derived from periwinkle, prevent the growth of cancerous cells
• ecological services
  • ecological service: a benefit that people receive from an ecosystem
  • eg. pollination, carbon capture, flood control, erosion control, and water purification
• aesthetic and recreational opportunities
  • ecotourism: tourism directly created by ecological sites; an important sector of the economy in many countries
  • however, overcrowding of natural areas may be counterproductive
• existence value and intrinsic value
  • existence value: the positive sentiment experienced by people simply knowing that something exists, even if they don’t personally benefit from it
  • intrinsic value: the idea that biodiversity is inherently valuable for its own sake

catalysts of declines in biodiversity

• habitat loss, fragmentation, and degradation
  • a major threat to biodiversity ⇒ arguably the most significant
  • eg. an owl lives in trees which are being cut down for logging
• overharvesting, overhunting, and overfishing
  • eg. elephants are hunted for ivory
• poaching: illegal hunting or fishing
  • invasive species/biological pollution
  • eg. too many rabbits in australia, do damage to native crops etc.
• species are usually introduced to a new area for food, aesthetic value, pest control, and/or by accident.
• pollution
  • eg. DDT (insecticide), plastics, lead
• bioaccumulation: the buildup of pollutants in an animal
• biomagnification: a process by which contaminant concentrations increase in the tissue of species at higher levels in the food chain
• climate change
  • responsible for more frequent fires, storms, and droughts
  • changing the distribution of tree species
• synergistic effects: multiple factors interact with one another, resulting in an overall effect that is greater than the sum of individual effects of any of them
  • eg. a combination of invasive species and climate change

protecting biodiversity

threatened vs. endangered species

• threatened species: a species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range
• endangered species: a species which in imminent danger of extinction throughout all or a significant portion of its range
• precautionary principle: an ounce of prevention is worth a pound of cure (benjamin franklin)
• action must be taken before a species is endangered or extinct

preserving species vs preserving ecosystems

• biodiversity hotspot: a region with a high level of biodiversity which is prioritized when looking to obtain the maximum possible benefit in protecting biodiversity

protecting and restoring biodiversity — possible solutions

• conservation biology
  • mission-oriented crisis discipline, multidisciplinary science that has developed to address the loss of biodiversity
  • two central goals: evaluate human impact on biodiversity, develop practical approaches to prevent extinction of species (scitable)
• laws and policy
• endangered species act (1973) — established protections for fish, wildlife, and plants listed as threatened or endangered; provides for adding/removing species to/from the list of threatened and endangered species, and for preparing/implementing plans for their recovery
  • contains “no-take provision” — landowners cannot cause harm to listed species
  • ESA habitat conservation plan grants exceptions to “no-take provision” principle
  • eg. landowner may cut down trees, removing habitat for a local species, as long as they have a plan to mitigate the effect on the environment
  • success story — bald eagle has recovered from endangered status due to the banning of pesticides such as DDT
• international treaties
• convention on international treaties in endangered species (CITES — 1973): international agreement between governments aiming to ensure that international trade in specimens of wild animals and plants does not threaten the survival of the species
• convention on biological diversity (CBD — 1992): governments agree to conserve and sustainably use biodiversity, required to develop national biodiversity strategies and action plans
• captive breeding and reintroduction programs
  • eg. egg pulling, incubators, artificial insemination, surgical implantation of eggs into surrogate mother, cross-fostering, cloning
• institutions that protect biodiversity eg. gene banks, seed banks, arboretums, botanical gardens, zoos, aquariums
• protected areas
  • protected area: an area of land and/or sea especially dedicated to the protection of biological diversity and of natural and associated cultural resources, managed through legal of other effective means
  • eg. national parks

\