Lecture Exam 4

• Extinction

  When a species completely dies out. 
• Endangered Species Act 1973:


  enacted after increasing public concern in the 1960’s about increasing numbers of extinctions
• Define Mass Extinction:


  50% - 90% Of all living species lost.
• Causes of mass extinction:

  Change in sea levels, Climate fluctuations, Shifts in ocean and landforms from continental drift, Asteroid impact ALL cause a mass extinction. 
• How many previous mass extinctions have there been?

  5 in the Earth’s History
• What is the background extinction rate?


  Rate at which species are lost from a normal evolution
• Average lifespan of a species:

  1 Million Years
• Overall rate of extinction:

  1 species per million every year: 0.001%
• What is the current extinction rate?:

  0.005%
• To be considered extinct, no individuals of a species have been seen in the wild for how many years?

  50
• Habitat


  the natural home or environment of an animal, plant, or other organism.
• Lost Habitat =


  Lost Species
• Species Area Curve


  Can be used to predict the loss of species that would correspond to a loss of habitat area.
• Habitat Fragmentation 


  Habitat fragmentation can upset the ecosystem’s Food chains/food webs / Difficult to leave
• Invasive Species 


  as an organism that is not native and has negative effects on our economy, our environment, or our health. 
• Over Harvesting / Overexploitation:


  Harvesting of animals for animal parts, rituals, or illegal poaching. 
• Pollution


  release of poisons, excess nutrients, and other wastes into the environment
• Eutrophication


  When fertilizer runs into ponds, algae populations grow along with bacterial populations, and results in oxygen depletion and large fish kills. 
• Food Web


  complex linkage among organisms within a community
• Consequences of Extinction:


  Loss of Resources, Disruption of Ecological Communities
• Food Chain


  flow of energy in one direction within an ecological system
• Producers


  Photosynthetic Organisms, produce Glucose
• Primary consumers


  Feed on Producers, Turn glucose into Mechanical energy
• Secondary Consumers


  Predators feeding on primary consumers
• Tertiary Consumers


  carnivore at the topmost level in a food chain that feeds on other carnivores
• Mutualism


  association increases the growth or population size of both species.
• Competition


  two species of organisms both require the same resource in a habitat.
• Commensalism


  increases the growth or population size of one species and does not affect the other species.
• Predation


  Consumption of one organism by another.
• Parasitism


  When a parasite consumes a animal
• Define a Keystone species:


  single species that indirectly affects more than one other species to the extent that – if it is removed – the community collapses
• Examples of a Keystone Species


  Sea Otters, Gray Wolves, Prairie Dogs
• What is a Biological Hotspot?

  Region with high biological diversity.
• How many biodiversity hotspots are there

  25
• Biological hotspots are what percent of the earths surface

  2%
• Biological Hotspots contain?


  50% of all mammal, bird, reptile, amphibian, and plant species
• Ecotourism


  Responsible travel to natural areas which conserves the environment and improves the welfare of local people.
• Genetic Drift


  the chance change in the frequency of an allele within a population.
• How does Genetic Drift relate to extinction?:


  Genetic drift occurs more rapidly as population size decreases, and is more likely to result in complete loss of alleles
• What is so great about genetic variability within a species?: 


  allows species to adapt to future environmental changes and avoid inbreeding.