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This Chapter Not in the Book Conserving Biodiversity Community and Ecosystem Ecology Fourth Edition BIOLOGY Science for Life | with Physiology Colleen Belk • Virginia Borden Maier © 2013 Pearson Education, Inc. Copyright © 2009 Pearson Education, Inc. PowerPoint Lecture prepared by Jill Feinstein Richland Community College 1 The Sixth Extinction Endangered Species Act (ESA) – law passed in 1973 to protect and encourage population growth of threatened and endangered species Biodiversity – the entire diversity of living organisms in an area Extinction – the complete loss of a species © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Measuring Extinction Rates History of life on earth has been punctuated with five mass extinctions. © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Measuring Extinction Rates Is the sixth mass extinction event occurring now? Need to know the background extinction rate Fossils indicate that average species exists for ~1,000,000 years Estimate of background extinction rate is 0.0001% per year © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Measuring Extinction Rates Current rate of extinction – three times more bird and mammal species have disappeared in the last 150 years than in the previous 200 years © 2013 Pearson Education, Inc. 1 The Sixth Extinction – The Causes of Extinction The most severe threats to species loss come from four general categories: Loss or degradation of habitat Introduction of non-native species Overexploitation of species Pollution © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Habitat Destruction and Fragmentation Habitat is the place where a particular species lives and obtain resources for survival. As human population increases, pressure on natural areas increases Species area curve measures the relationship between the size of a natural area and the number of species it can support. Habitat destruction affects all ecosystems. If worldwide habitat destruction continues at present rate, as many as 25% of world’s species could become extinct. © 2013 Pearson Education, Inc. Animation: Tropical Deforestation And The Species Area Curve Click “Go to Animation” / Click “Play” © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Habitat Destruction and Fragmentation Predicting extinction caused by habitat destruction © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Habitat Destruction and Fragmentation Usually human activity results in habitat fragmentation – large natural areas subdivided into smaller areas Large predators are threatened because they require large home ranges. © 2013 Pearson Education, Inc. Animation: Habitat Destruction And Fragmentation Click “Go to Animation” / Click “Play” © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Habitat Destruction and Fragmentation Basic rule of biological systems: energy flows in one direction along a food in chain within an ecosystem The sun provides energy to the producers which are feed on by the primary consumers who are feed upon by the secondary consumers. © 2013 Pearson Education, Inc. 1 The Sixth Extinction - Introduced Species Introduced species – nonnative species introduced to a new area either purposely or accidentally by human activity Most groups of species in an area undergo coevolution. introduction of non-native species is often destructive because they have not evolved with local species Brown tree snake, introduced to Guam, caused many local bird species to go extinct © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Overexploitation When human use of a natural resource exceeds its reproductive rate, overexploitation occurs. Can occur if species is highly prized by humans, which can spur illegal hunting Can also occur if species competes with humans (i.e., wolves and ranchers) © 2013 Pearson Education, Inc. 1 The Sixth Extinction – Pollution The release of poisons, toxins, excess nutrients, and other waste products – pollution – is another threat to biodiversity. Excess fertilizer runoff leads to eutrophication of waterways Eutrophication is the excess growth of bacteria that depletes oxygen from the water Carbon dioxide is another atmospheric pollutant, associated with climate change © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Loss of Resources Loss of species can lead to economic impacts for humans. Some biological resources harvested directly include wood (lumber and fuel), shellfish (protein), and algae (gelatin). Wild species provide biological chemicals (medicines). Wild species have alleles that are not present in domestic species, which can increase vigor of domesticated species. Wild species can contribute other means of combating pests (biological control). © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Predation, Mutualism, and Competition Derailed Species interact with one another and their environment in complex ways, not just a simple food chain instead as a food web. © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Mutualism: How Bees Feed the World Mutualism – relationship in which both species benefit from their interaction, for example: Cleaner fish Fungal mycorrhizae Ants and acacia trees Bees are primary pollinators of many wild plants Wild bees pollinate 80% of agricultural crops in U.S. Bee populations are falling due to “colony collapse disorder” Humans benefit from mutualism, and will lose if bees go extinct Commensalism is a relationship where one species benefits and the other is unaffected. © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Predation: How Songbirds May Save Forests Predator – species that survives by eating other species Songbirds consume many insects Most insects eaten by songbirds consume plants Songbirds help to sustain forests As songbird numbers decline, damage to forests increases © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Competition: How a Deliberately Infected Chicken Could Save a Life A leading cause of food illness in the U.S. is caused by Salmonella enteritidis. About 2 million Americans infected each year About 400 die each year as a result of infection Most common source of infection is eggs S. enteritidis contaminates egg when it forms in the hen © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Competition: How a Deliberately Infected Chicken Could Save a Life Competitive exclusion is the use of food and space resources, making it impossible for another species to establish itself. On this principle, chickens are deliberately infected with harmless bacteria. Harmless bacteria establish and prevent S. enteritidis from living in chicken’s gut thus decreasing the number of eggs infected with S. enteritidis. © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Competition: How a Deliberately Infected Chicken Could Save a Life © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Competition: How a Deliberately Infected Chicken Could Save a Life Competition between species can have consequences for humans as well. Mosquitos, snails and tadpoles compete for same resources in ponds When populations of snails and tadpoles decrease, mosquitoes increase Potentially serious because mosquitoes can spread malaria, West Nile virus, and yellow fever © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Keystone Species: How Wolves Feed Beavers Keystone species are key figures in determining the food web of an ecosystem. Wolves were eradicated from Yellowstone Park in 1920s With wolves gone, biologists noted declines in aspen, cottonwood, and willow trees Trees declined due to predation by elk Trees are crucial for beavers, songbirds, and fish With reintroduction of wolves, trees and other species rebounded © 2013 Pearson Education, Inc. 2 The Consequences of Extinction –Keystone Species: How Wolves Feed Beavers © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Disrupted Energy and Chemical Flows An ecosystem is defined as all of the organisms in a given area, along with their non-biological enivornment. Energy flow - only a small portion (~10%) of the energy in one level of a trophic pyramid can be converted to biomass at the next level Diversity also affects energy flow, such as in more diverse grasslands, more biomass is produced © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Disrupted Energy and Chemical Flows Nutrient cycling – nutrients that pass through a food web rarely leave the system © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Disrupted Energy and Chemical Flows The soil community has an important role in nutrient cycling. Decomposers return nutrients back in to the soil for use by plants Introduction of non-native earthworms in NE U.S. had dramatic impact on forest plants Non-native worms changed the soil community © 2013 Pearson Education, Inc. 2 The Consequences of Extinction – Psychological Effects Our experience with nature has strong psychological effects Dental patients viewing landscapes showed a decrease in blood pressure Hospital patients who could view trees recovered from surgery more quickly Instinctive desire to commune with nature is called biophilia Loss of biodiversity could make human experience less pleasant © 2013 Pearson Education, Inc. 3 Saving Species – Protecting Habitat Less than 2% of the earth’s surface contain up to 50% of the earth’s mammal, bird, reptile, and plant species. These areas are biodiversity hotspots. © 2013 Pearson Education, Inc. 3 Saving Species – Protecting Habitat Converting wild areas to agricultural production is a major cause of habitat destruction. Ways to decrease the rate of habitat destruction Altering our consumption patterns can help decrease habitat destruction Eating low on the food chain (less meat and dairy) makes a difference Increased financial aid to developing countries can also help So can slowing human population growth rate © 2013 Pearson Education, Inc. 3 Saving Species – Protection From Environmental Disasters A large population provides group protection from environmental disaster. A species with a slow growth rate is at greater risk if its numbers diminish. The longer a population remains small, the greater its risk. © 2013 Pearson Education, Inc. 3 Saving Species – An Overview of Conservation Genetics Genetic variability is the sum of all of the alleles and their distribution within the species. Loss of genetic variability is a two-fold problem. Low genetic variability leads to low fitness, and is more likely to express harmful mutant alleles. Rapid loss of genetic variability can lead to extinction due to the low fitness of individuals. © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics The importance of genetic variability When individuals are heterozygotic for many genes, the overall effect is greater fitness. © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics Heterozygotes can avoid deleterious effects of recessive alleles. © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics In a small population, individuals are more likely to be related to their mates. Result can be inbreeding depression, a decline in heterzygotes Because of this, cheetahs have poor quality sperm and low rate of cub survival In humans, children of first cousins have lower rates of heterozygosity and higher rates of infant mortality © 2013 Pearson Education, Inc. 3 Saving Species - A Closer Look: Conservation Genetics Small populations lose their genetic variability due to genetic drift. © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics The consequences of low genetic variability in a population A small population can become stuck in a cycle that leads to extinction. This is called the extinction vortex © 2013 Pearson Education, Inc. 3 Saving Species – A Closer Look: Conservation Genetics Irish potato is a human example of the potentially disastrous effects of low genetic diversity In 1850s, Irish potato crop had very low genetic diversity Fungus that causes potato blight arrived in Ireland; plants rotted in fields Because of crop failure, nearly 1 million Irish died of starvation and disease © 2013 Pearson Education, Inc. 4 Protecting Biodiversity Versus Meeting Human Needs The protection of endangered species sometimes has effects on human livelihood. Farmers were unable to use water for irrigation because diversion of water would have disrupted fish populations. Endangered Species Act has helped save American alligators, peregrine falcons, and bald eagles. © 2013 Pearson Education, Inc. 4 Protecting Biodiversity Versus Meeting Human Needs © 2013 Pearson Education, Inc. Which cause of extinction poses the most serious threat to biodiversity today? degradation of habitat introduction of nonnative species overharvesting effects of pollution © 2013 Pearson Education, Inc. Which cause of extinction poses the most serious threat to biodiversity today? degradation of habitat introduction of nonnative species overharvesting effects of pollution © 2013 Pearson Education, Inc. Based on this graph, what would you predict would be the result of decreasing the habitable area of an island? The number of species on it would increase. The number of species on it would not be affected. The number of species on it would decrease. There is no way to predict what would happen. © 2013 Pearson Education, Inc. Based on this graph, what would you predict would be the result of decreasing the habitable area of an island? The number of species on it would increase. The number of species on it would not be affected. The number of species on it would decrease. There is no way to predict what would happen. © 2013 Pearson Education, Inc. How many square kilometers of rain forest are cut each year in South America’s Amazon River Basin? 1,000 5,000 10,000 20,000 © 2013 Pearson Education, Inc. How many square kilometers of rain forest are cut each year in South America’s Amazon River Basin? 1,000 5,000 10,000 20,000 © 2013 Pearson Education, Inc. Habitat fragmentation is especially threatening to ____________. small decomposers large plants small herbivores large predators © 2013 Pearson Education, Inc. Habitat fragmentation is especially threatening to ____________. small decomposers large plants small herbivores large predators © 2013 Pearson Education, Inc. Which of these terms best describes a dairy cow? producer primary consumer secondary consumer decomposer © 2013 Pearson Education, Inc. Which of these terms best describes a dairy cow? producer primary consumer secondary consumer decomposer © 2013 Pearson Education, Inc. The relationship where cleaner fish remove and consume parasites from the bodies of larger fish is known as __________. parasitism mutualism commensalism competition © 2013 Pearson Education, Inc. The relationship where cleaner fish remove and consume parasites from the bodies of larger fish is known as __________. parasitism mutualism commensalism competition © 2013 Pearson Education, Inc. True or False: An ecosystem is defined as all of the organisms in a given area, along with their nonbiological environment. True False © 2013 Pearson Education, Inc. True or False: An ecosystem is defined as all of the organisms in a given area, along with their nonbiological environment. True False © 2013 Pearson Education, Inc. Which of the following statements is incorrect? Small populations are at higher risk for extinction. Small populations are at greater risk when individuals have low fitness due to inbreeding. Small populations are at risk of losing genetic variability due to genetic drift. Small populations are more able to evolve in response to environmental change. © 2013 Pearson Education, Inc. Which of the following statements is incorrect? Small populations are at higher risk for extinction. Small populations are at greater risk when individuals have low fitness due to inbreeding. Small populations are at risk of losing genetic variability due to genetic drift. Small populations are more able to evolve in response to environmental change. © 2013 Pearson Education, Inc. Why was there a debate over the shortnose suckers? The shortnose suckers were aggressive towards humans. The shortnose suckers were beyond saving. The human economy in the Lost River was suffering due to the Endangered Species Act. The God squad was used. © 2013 Pearson Education, Inc. Why was there a debate over the shortnose suckers? The shortnose suckers were aggressive towards humans. The shortnose suckers were beyond saving. The human economy in the Lost River was suffering due to the Endangered Species Act. The God squad was used. © 2013 Pearson Education, Inc. Each jacket represents an allele. Which of the jacket pictures has the highest fitness for responding to a changing environment? the homozygote suit coat the homozygte winter coat the heterozygote with one of each jacket © 2013 Pearson Education, Inc. Each jacket represents an allele. Which of the jacket pictures has the highest fitness for responding to a changing environment? the homozygote suit coat the homozygte winter coat the heterozygote with one of each jacket © 2013 Pearson Education, Inc.