Chapter 9: Sustaining Biodiversity
Extinction Fossil record shows evidence of extinction as a natural process: background or natural rate of extinction: loss of species at a low rate mass extinction : widespread extinction of large numbers of species The real reason dinosaurs went extinct 5 mass extinctions in the past (last one was 65 million years ago Causes of mass extinctions: abrupt climate changes, such as a meteorite impact event
Are Humans Causing a Mass Extinction? Species are becoming extinct times faster than they were before modern times. By the end of this century, the extinction rate is expected to be 10,000 times the background rate. Conservative estimates of extinction = Growth of human population will increase this loss E.O. Wilson estimates that if 1% extinction rate, 1/2 of all species will be gone by 2100
Threatened & Endangered Species Endangered Species: Species that has so individuals that the species could soon become extinct over some or most of its natural range. Threatened Species: Species that is still relatively abundant, but because of is likely to become endangered in the near future.
Percentage of Various Species Threatened with Premature Extinction
Threatened & Endangered Species Worldwide about 25% of mammals are at risk of extinction. The highest percentages at risk are: apes & monkeys ( ) moles & shrews ( ) antelopes & cattle ( ) Tasmanian Tiger (extinct)
Estimates from the IUCN (International Union for Conservation of Nature)
Why Preserve Wild Species? economic & importance scientific & importance: ecological services include nutrient recycling, watershed value, production of oxygen, moderating climate, & detoxifying toxic substances http://www.youtube.com/watch?v=8shr4zti5py Bioremediation: To solve (remedy) an environmental problem using a living thing. http://permaculturenews.org/2014/04/10/bioremediationindustrial-pollution-utilizing-fungi-bacteria-plants-reduce-oilpollution-ecuadorian-amazon-basin-world/ & recreational importance
Causes of Extinction & Depletion HIPPCO, fragmentation & degradation I (nonnative) species P and resource use growth P C O (poaching, overfishing etc.)
1. Habitat Loss/Fragmentation Most Serious Threat to Biodiversity Indian Tiger Black Rhino African Elephant Asian or Indian Elephant Former Range Current Range
Habitat Fragmentation Reduces Genetic Diversity in a Population Area preserved for wildlife refuge must have adequate population size for genetic diversity Why is Genetic Diversity Important? Improves odds that members of population will be able to survive http://evolution.berkeley.edu/evolibrary/article/_0_0/agriculture_02
Habitat Loss and Migratory Birds Managing populations of waterfowl is difficult: Birds need for habitat (places along whole route Wetlands are critical, yet are quickly disappearing Requires efforts to protect habitats along the flyways.
2. Introduction of Invasive Species Zebra Mussels in the Great Lakes (accidental-ballast water) Introduction can be either deliberate or accidental Nonnative species may have no natural Zebra Mussels Kudzu Examples: Kudzu in Southeastern US (deliberate)
2. Invasive Species Once a species is introduced to an area, it is difficult to turn back the clock and eradicate it. The more time before control measures are taken, the less likely the efforts will succeed.
2. Invasive Species Ballast Water: Accidental Shipping Routes
Biological Control Gone Bad In the 1930 s cane toads were introduced into Australia to control beetle populations that was devastating the cane sugar crop. Cane toad did not control the beetle population, yet its population grew exponentially in Australia. Cane Toads are poisonous, and are able to outcompete many native species.
3. Population Growth and Resource Use
4. Pollution Pacific Ocean Garbage Patch
4. Pollution Bee colony collapse syndrome Honeybees responsible for 80% of insect-pollinated plants, including many important crops like apples, almonds Dying due to Pesticides? Parasites?
5. Climate Change
6. Overexploitation Case Study: Overfishing Major commercial fishing methods. Modern methods enable increasing harvest of decreasing populations.
6. Overexploitation Overfishing: Whales Prior to 1986, overharvest drove major whale populations to commercial extinction. Populations are in process of recovering since the 1986 International Whaling Ban.
Characteristics of Extinction Prone Species: low (e.g., blue whale, California condor) specialized (e.g., giant panda) feed at high (e.g., Bengal tiger) large (e.g., Asian elephant) limited (e.g., green sea turtle) limited (e.g., woodland caribou)
Characteristics of Extinction Prone Species Cont. fixed patterns (e.g., whooping crane) preys on (e.g., timber wolf) small (e.g. endemic island species) commercially valuable (e.g. rhinos for horns) behaviors that contribute to extinction (e.g., Carolina parakeet- flocks hover over injured bird.)
Why are top consumers more vulnerable to extinction? Must be by a large amount of producers/lower consumers. Much of energy consumed is given off as heat. Therefore, there is less energy available for higher trophic levels (animals higher in the food chain).
Top Consumers also suffer from: Harmful concentrations of toxins get stored in body tissue such as fat. Due to the energy pyramid, toxins get up the food chain.
Worldwide Extinctions
Biodiversity Hotspots
Protecting Biodiversity Two approaches to species protection: approach: aims to preserve balanced populations of species in their native habitats; advantage: it focuses on protecting sufficient land to protect ecological integrity & provide habitat for the majority of wild species; approach: based on identifying & protecting endangered species on a case by case basis; advantage: it identifies which species are at greatest risk & focuses attention on those species. consensus among conservation biologists is that protecting biodiversity requires both approaches
International Treaties on Biodiversity 1975: Convention on International Trade in Endangered Species (CITES) Signed by countries International trade regulation for endangered species. For example- ban on ivory trade. 1992: Convention on Biological Diversity (BCD) Focuses on ecosystems Ratified by countries (not the U.S.)
Example of an issue for consideration by CITES: International trade of rhino horn is banned by CITES, but due to the high price of rhino horn poaching is a persistent problem. The next CITES delegation will consider whether to allow farming of rhino for their horns. Discuss pros and cons of this strategy: Pros- creates source of horn without killing of wild rhinos. Cons- hard to determine source of horn and could facilitate the sale of horn from wild sources. Farming of crocodiles for their skins helped to preserve wild crocodile populations.
World Protected Areas
The Good News: More land is being protected over time
Protecting Biodiversity Unlike traditional parks & reserves, biosphere or nature reserves recognize local people's needs for access to sustainable use of resources in parts of the reserve.
Protecting Wild Species in the United States Endangered Species Act (ESA) of 1973 requires listing & protection of endangered & threatened species in US. Government Agencies Involved: (NMFS) charged with protection of marine species; charged with listing & California Condor protection of all other species; Florida panther
Success Story: Bald Eagle
U.S. Wilderness Areas US Wilderness Society estimates that a wilderness area should be at least in order to be protected from human activity. About of US land area is protected as wilderness: ¾ is in Alaska About of land area in lower 48 states is protected wilderness areas in lower 48 states: only are larger than 4,000 km 2 About 400,000 km 2 (150,000 mi 2 ) of public lands could still qualify as wilderness areas, but strong opposition to setting these lands aside exists from timber, mining, ranching, energy, and other interests