Extinction Extinction The Definition and Causes What is

Extinction

Extinction The Definition and Causes

What is Extinction? Ø Extinction occurs when the last existing member of a given species dies l In other words…there aren’t any more left! Ø It is a scientific certainty when there are not any surviving individuals left to reproduce Ø Functional Extinction l l Only a handful of individuals are left Odds of reproduction are slim

Causes of Extinction Ø Genetics and Demographics l l Small populations = increased risk Mutations • Causes a flux in natural selection • Beneficial genetic traits are overruled l Loss of Genetic Diversity • Shallow gene pools promote massive inbreeding

Causes Con’t. Ø Habitat Degradation l l One of the most influential Has many causes Some due to humans Some due to other factors

Habitat Degradation Ø Toxicity l l Kills off species directly through food/water Indirectly via sterilization Can occur in short spans (a single generation) Can occur over several generations • Increasing toxicity • Increasing competition for habitat resources

Habitat Degradation Ø Destruction of Habitat l l l “Save the Rainforests!” Elimination of living space Change in habitat • Rainforest to pasture lands l Leads to diminishing resources • Increases competition l Can be caused by natural processes • Volcanoes, floods, drought, etc…

Causes Con’t. Ø Predation l l Competition Disease Ø Coextinction Ø Mass Extinction Ø Planned Extinction

Predation Ø Introduction of predators l l Invasive alien species Transported by humans • Cattle, rats, zebra muscles, etc… • Sometimes on purpose, sometimes not l l l Can eat other species Eat food sources Introduce diseases

Coextinction Ø The loss of one species leads to the loss of another Ø Chain of extinction Ø Can be caused by small impacts in the beginning Ø A predator looses its food source Ø Affected by interconnectedness in nature

Mass Extinction Ø Aka: an extinction event Ø A sharp decrease in the number of species on Earth in a short period of time Ø Coincides with a sharp drop in speciation l The process by which new biological species arise Ø There have been at least 5 l Last one was 65 M years ago

Mass Extinction Diagram

Mass Extinction Ø Nearly 2/3 rds (or more) of all animal species that ever existed on the planet are now gone. • With contemporary extinction being attributed to HUMAN activity. Ø Numerous factors go into the extinction of a specific species. • Though all point the finger to climate change.

Mass Extinction Ø Began about three-million years ago (Continental Glaciations). Ø Hypotheses for initial extinction: • Sea level depletion vs. Temperature decrease Ø Though these hypotheses aren’t mutually exclusive, they may have conspired together.

Mass Extinctions 1. 2. 3. 4. 5. Cretaceous-Tertiary Extinction (65). End Triassic Extinction (200). Permian Triassic Extinction (250). Late Devonian Extinction (364). Ordovician-Silurian Extinction (440). (#= millions of years ago)

Planned Extinction Ø Human controlled Ø Thought of to help humans Ø Deadly viruses l Smallpox • Extinct in the wild l Polio • Near extinct (only in small parts of the world)

Natural Causes of Extinction

Climatic Heating and Cooling

Changes in Sea Level or Currents Ø www. johnstonsarchive. net/spaceart/cylmaps. html

Asteroids Ø Causes complete devastation Ø Flattening and crater at or around impact sitehundreds of miles wide Ø Reverberations felt around the world

Cosmic Radiation Ø www. iit. edu/~ipro 313 s/home. html

Acid Rain Ø Kills acid intolerant species

Disease/Epidemics Ø Can wipe out entire species Ø Frog with fungus disease Ø Killing frogs and other amphibians

Spread of Invasive Species

Natural factors usually occur at a slower rate and therefore cause a low extinction rate. Human activities occur at a faster rate and cause higher extinction rates. Human activities are mostly responsible for the present extinction rates. http: //www. gov. mb. ca/conservation/sustain/extinct. pdf

Human Causes of Extinction

Top Human Causes of Extinction: Increased human population Destruction/Fragmentation of habitat Pollution Climate change/Global warming

Extinctions caused by humans are generally considered to be a recent phenomena. HOWEVER: • In Australia—earliest humans: 64, 000 years ago extinction— 30, 000 -60, 000 years ago • In the Americas— 80% of large animals became extinct around the same time as first human presence there

Based on these, and other studies done by The international Union for Conservation of Nature and Natural Resources (IUCN), human induced extinctions are not necessarily a new phenomena. However, extinction by humans today is becoming much more rapid.

The rapid loss of species today is estimated by some experts to be between 100 and 1, 000 times higher than the natural extinction rate, while others estimate rates as high as 1, 000 -11, 000 times higher.

Habitat Degradation Habitat loss and degradation affect 86% of all threatened birds, 86% of mammals and 88% of threatened amphibians

Climate change/Global Warming John W. Williams from UW-Madison suggests that changes in regions such as the Peruvian Andes, portions of the Himalayas and southern Australia could have a profound impact on indigenous plants and animals Williams and his research partners used computer models to estimate how various parts of the world would be affected by regional changes consistent with the IPCC's climate models. Their findings indicated that “By the end of the 21 st century, large portions of the Earth’s surface may experience climates not found at present and some 2 th century climates may disappear. ”

Their studies also suggest isolated climates such as the Peruvian Andes could change drastically enough to lead to species extinctions. The climate change might also create new climates, providing new opportunities for other species to thrive, Williams said. Regions where novel climates are expected to form in tropical and subtropical regions include the western Sahara, southeastern U. S. and eastern India.

Extinction Hotspots

Where and what are hotspots? Ø “The concept of biodiversity hotspots was penned by British ecologist Norman Myers in 1988 as a means to address the dilemma of identifying the areas most important for preserving species. ” (national geographic) Ø Hotspots are included in 6 continents excluding Antarctica. Ø Hotspots are heavily distributed along shore lines and near the equator.

Ø Hotspots are effected by many factors including l l l Logging Agriculture Hunting Climate change Government Ø Hotspots can be added and removed from the classification of “hotspot” by what recovery or lack of prevention is taking place in each area.

What is required to be considered a hotspot Ø “The region must support at least 1, 500 plant species found nowhere else in the world, and it must have lost at least 70 percent of its original habitat. ”

Interactive maps Ø http: //www. biodiversityhotspots. org/xp/Hot spots/home/interactive_map. xml Ø http: //www. zeroextinction. org/pointmapper/ azefiles/index. html

What is Biodiversity? Biodiversity is the variation of taxonomic life forms for a given biome or ecosystem Ø Boosts Ecosystem productivity Ø Measure of the health of a biological system Ø

Benefits of Biodiversity Ø Food and drink Ø Medicines Ø Industrial materials Ø Ecological services Ø Leisurely, cultural, and Ø aesthetic values

Causes of Biodiversity Loss Ø Ø Ø Ø Pollution Loss of tropical forest Spread of urban areas Warfare Large dam construction Road building Tourism Loss of traditional lifestyles

Consequences of Biodiversity Loss of food Ø Decrease in biomass Ø Collapse of food web Ø Loss of keystone species Ø Reduction of ecosystem efficiency and community productivity Ø Loss of medicinal supplies Ø Increased vulnerability of species to disease and predation Ø

Crops ØMonoculture of crops lets the yield become susceptible to pests or viruses Ø 75% of crop varieties are extinct ØDue to the spread of modern agriculture

Tropical Forest Cutting Cover 13% of Earth Ø Home to 50% of all known plant and animal species Ø FAO reports 15. 4 million hectares are destroyed annually Ø

The Convention on Biological Diversity Mission Statement “The objectives of this convention are the conservation of biological diversity, sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources. ” Ø Since it was adopted at the Earth Summit in Rio de Janeiro in 1992, 189 countries have signed and implemented it. The United States signed it in 1993 but has yet to put it into action still today

The Convention on Biological Diversity 2010 Biodiversity Target Members adopted a plan to significantly reduce the present rate of biodiversity loss at the global, regional and national level by the year 2010.

References Ø Ø Ø Ø Ø Ceballos, G. , and Ehrlich, P. , 2002, Mammal Population Losses and the Extinction Crisis: Science, v. 296, p. 904 -908. Fahrig, L. , 2002, Effect of Habitat Fragmentation on the Extinction Threshold: A Synthesis: Ecological Applications, v. 12, p. 346 -353. Gittleman, J. , The Risk of Extinction—What you don’t know will hurt you: Science, v. 291. Petcchey, O. L. , and Gaston, K. J. , Extinction and the loss of functional diversity: They Royal Society, p. 1721 -1727. Rutledge, D. , Lepczyk, C. , Xie, J. , Liu, J. , 2001, Spatiotemporal Dynamics of Endangered Species Hotspots in the United States: Conservation Biology, v. 15, p. 475 - 487. Kent, Holsinger. "The Causes of Extinction. " 27 Aug. 2005. 12 Mar. 2007 <http: //darwin. eeb. uconn. edu/eeb 310/lecture-notes/extinctions/node 3. html>. Madeley, J. , Warnock, K. , 1995, Biodiversity: A Matter of Extinction: The challenge of protecting the South’s biological heritage <http: //www. panos. org. uk/pdf/reports/ biodiversity. pdf>. Trombulak, Stpehen C. , et. Al. 2004, Principles of Conservation Biology: Recommended Trombulak, Stpehen Guidelines for Conservation Literacy from the Education Committee of the Society for Bald Eagle. US Fish and Wildlife Service <http: //www. fws. gov/endangered/i/b/msab 0 h. html>. Conservation Biology: Conservation Biology <http: //www. conbio. org/Resources/Education/conservation_literacy_english. pdf>. Extinction. Lecture by Bruce Walsh at University of Arizona, 1995. <http: //nitro. biosci. arizona. edu/courses/EEB 105/lectures/extinction. html>.

References Trombulak, Stpehen C. , et. Al. 2004, Principles of Conservation Biology: Recommended Guidelines for Conservation Literacy from the Education Committee of the Society for Bald Eagle. US Fish and Wildlife Service <http: //www. fws. gov/endangered/i/b/msab 0 h. html>. Conservation Biology: Conservation Biology <http: //www. conbio. org/Resources/Education/conservation_literac y_english. pdf>. Extinction. Lecture by Bruce Walsh at University of Arizona, 1995. <http: //nitro. biosci. arizona. edu/courses/EEB 105/lectures/extinctio n/extinction. html>.