Chapter 11 Conserving Biodiversity Community and Ecosystem Ecology

§ 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 Copyright © 2010 Pearson Education, Inc.

§ History of life on earth has been punctuated with five mass extinctions Number of marine families Mass extinctions Are we now experiencing the beginning of biodiversity’s sixth mass extinction? Millions of years ago Copyright © 2010 Pearson Education, Inc. Figure 14. 2

§ Is the sixth mass extinction event occurring now? § Need to know the background extinction rate § Fossils indicate that average species exists for ~1, 000 years § Estimate of background extinction rate is 0. 0001% per year Copyright © 2010 Pearson Education, Inc.

§ Current rate of extinction – more bird and mammal species have disappeared in the last 150 years Number of species going extinct Birds Mammals More than three times as many birds and mammals have gone extinct in the last 150 years than had in the previous 200 years. 50 -year periods Copyright © 2010 Pearson Education, Inc. Figure 14. 4

§ The most severe threats to species loss come from four general categories: 1. 2. 3. 4. Loss or degradation of habitat Introduction of non-native species Overexploitation Pollution Copyright © 2010 Pearson Education, Inc.

§ 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 – the number of species that a natural area of a given size can support § Habitat destruction not limited to rainforests; freshwater lakes and streams, grasslands, and temperate forests are also threatened § If worldwide habitat destruction continues at present rate, as many as 25% of world’s species could become extinct Copyright © 2010 Pearson Education, Inc.

1 The Sixth Extinction – Habitat Destruction and Fragmentation § Predicting extinction caused by habitat destruction § Diversity increases with area; should decrease with loss of area Copyright © 2010 Pearson Education, Inc.

§ Usually human activity results in habitat degradation – large natural areas forever destroyed § Or habitat fragmentation – large natural areas subdivided into smaller areas § Large predators are threatened because they require large home ranges Copyright © 2010 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, but VERY inefficiently! § The sun provides energy to the producers which are feed on by the primary consumers who are feed upon by the secondary consumers. Too many new predators disrupts the natural food pyramid, and forces competition among predators for limited food supply and energy resources Copyright © 2010 Pearson Education, Inc.

Figure 14. 5 c § Introduced species – nonnative species introduced to a new area either purposely or accidentally by human activity § Often destructive because they have not co-evolved with local species § Brown tree snake, introduced to Guam, caused many local bird species to go extinct § Domestic cats in Wisconsin kill 39 million birds/year § Pythons in Florida Everglades Copyright © 2010 Pearson Education, Inc. http: //newswatch. nationalgeographic. com/2010/01/ 25/florida_python_hunter/

§ 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) Copyright © 2010 Pearson Education, Inc.

§ 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 or other microbes that depletes oxygen from the water § Carbon dioxide is another atmospheric pollutant, associated with climate change Copyright © 2010 Pearson Education, Inc.

Consequences of Extinction § Loss of resources § Loss of species § Predation, Mutualism and Competition Derailed § Keystone Species disrupted § Disrupted Energy and Chemical Flows § Psychological Effects Copyright © 2010 Pearson Education, Inc. Figure 14. 11

§ 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) Copyright © 2010 Pearson Education, Inc.

§ Species interact with one another and their environment in complex ways, not just a simple food chain Other birds Smaller-toothed whales Other seals Sperm whales Leopard seal Baleen whale Elephant sea; Penguins Carnivorous zooplankton Fish Krill Copyright © 2010 Pearson Education, Inc. Squid Phytoplankton Other herbivorous zooplankton

Other birds Smaller-toothed whales Other seals Sperm whales Leopard seal Baleen whale Elephant sea; Penguins Carnivorous zooplankton Fish Squid Krill Copyright © 2010 Pearson Education, Inc. Other herbivorous zooplankton Phytoplankton Figure 14. 12

§ Mutualism – relationship in which both species benefit from their interaction § Many examples §. Cleaner fish 1. Fungal mycorrhizae 2. Ants and acacia trees 3. (see https: //www. youtube. com/watch? v=Xm 2 qdx. VVRm 4) § 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” and Zika spraying killing bees § Humans benefit from mutualism, and will lose if bees go extinct BEES: Copyright © 2010 Pearson Education, Inc. http: //www. youtube. com/watch? v=i. Nv. XDAk. Rz. Uw

§ Predator – species that survives by eating other species § Songbirds consume many insects § Most insects eaten by songbirds consume plants § Songbirds help to sustain forests keeping the insect population under control § As songbird numbers decline, damage to forests increases due to increase in insect numbers Copyright © 2010 Pearson Education, Inc.

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 inside chicken’s gut migrates to “birth canal” and contaminates egg when it forms in the hen Copyright © 2010 Pearson Education, Inc.

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 § On this principle, chickens are deliberately infected with harmless bacteria (other than those already living in chicken’s gut) § Harmless bacteria establish and prevent S. enteritidis from living in chicken’s gut, thus decreasing the number of eggs infected with S. enteritidis. Copyright © 2010 Pearson Education, Inc.

S. enteritidis has plenty of space to colonize, resulting in an active infection. Little bacteria is present in intestine. Chick Two options: (a) No treatment Number of bacteria How a Deliberately Infected Chicken Could Save a Life Hatching Intestine at hatching: no bacteria present. (b) Fed beneficial bacteria Interior surface of intestine is colonized by a diverse community of beneficial bacteria. Copyright © 2010 Pearson Education, Inc. Most of the S. enteritidis bacteria pass through because only a few of the cells can find a place to colonize. Number of bacteria Exposed to Salmonella enteritidis Hatching S. Enteritidis without competition Exposure to S. enteritidis To market Beneficial bacteria S. enteritidis with competition Exposure to S. enteritidis To market

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 Copyright © 2010 Pearson Education, Inc.

How Wolves Feed Beavers § Keystone species are key figures in determining the food web of an ecosystem § Wolves were eradicated from Yellowstone Park in 1920 s § 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 Copyright © 2010 Pearson Education, Inc.

§ 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 About 10% of energy taken in by deer is available to mountain lion. About 10% of energy taken in by grass is available to deer. Biomass in mountain lions Biomass in deer population Biomass in grass population Copyright © 2010 Pearson Education, Inc. Figure 14. 8

§ Nutrient cycling – nutrients that pass through a food web rarely leave the system Nitrogen (N 2) Animal protein Plant protein Dead organic matter Nitrate (NO 3–) Decomposers (bacteria and fungi) Nitrite (NO 2–) Copyright © 2010 Pearson Education, Inc. Nitrogen-fixing bacteria in plant root nodules Free-living, nitrogen-fixing bacteria Ammonia (NH 3) Figure 14. 18

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 Copyright © 2010 Pearson Education, Inc.

Psychological Effects of Extinction § 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 Copyright © 2010 Pearson Education, Inc.

Protecting Habitats 1. Protecting Habitats (biodiversity hotspots) 2. Decreasing Habitat Destruction 3. Protection from environmental disasters 4. Restore population numbers of species 5. Restore genetic diversity Copyright © 2010 Pearson Education, Inc. Figure 14. 21

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. Caucasus California Floristic Province Caribbean Mesoamerica Polynesia/ Micronesia Philippines South Central India. China Burma Mediterranean Basin Choco/ Darien Western Ecuador Tropical Andes Brazil’s Cerrado Polynesia/ Micronesia W. African Forests Western Ghats and Sri Lanka Tanzania and Kenya Sundaland Central Chile Diversity hot spots Copyright © 2010 Pearson Education, Inc. Brazil’s Atlantic Coast Succulent Karoo Wallacea New Caledonia Madagascar Cape Floristic Province Southwest Australia New Zealand Figure 14. 21

Decreasing Habitat Desctuction § Decreasing the Rate of Habitat Destruction § Converting wild areas to agricultural production is a major cause 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. § Adaptation of developed but nonagricultural areas to grow vegetation (hydroponics, integrated home/farm) offsets further agricultural development Copyright © 2010 Pearson Education, Inc.

§ A large population provides group protection from environmental disaster. (a) Lost River Sucker (b) California condor Number of individuals § 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. Rapid population growth rate Time (years) Copyright © 2010 Pearson Education, Inc. Slow population growth rate Time (years) Figure 14. 22

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. Copyright © 2010 Pearson Education, Inc.

3 Saving Species – A Closer Look: Conservation Genetics Copyright © 2010 Pearson Education,

§ The Importance of Genetic Variability § When individuals are heterozygotic for many genes, the overall effect is greater fitness. Being heterozygous may confer higher fitness for responding to a changing environment. Homozygote 1: Relatively low fitness (only one type of jacket in wardrobe) Homozygote 2: Relatively low fitness (only one type of jacket in wardrobe) Heterozygote: Relatively high fitness (two types of jackets in wardrobe) Copyright © 2010 Pearson Education, Inc. Figure 14. 23

§ Heterozygotes can avoid deleterious effects of recessive alleles. Being heterozygous may confer higher fitness by masking deleterious recessive alleles. Homozygote 1: Relatively high fitness (two functional jackets in wardrobe) Homozygote 2: Relatively low fitness (two nonfunctional jackets in wardrobe) Heterozygote: Relatively high fitness (one functional jacket in wardrobe) Copyright © 2010 Pearson Education, Inc. Figure 14. 24

§ 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 Copyright © 2010 Pearson Education, Inc.

3 Saving Species - A Closer Look: Conservation Genetics § Small populations lose their

§ The Consequences of Low Genetic Variability in a Population § A small population can become stuck in a cycle that leads to extinction. Small population Inbreeding Genetic drift Loss of genetic variability Reduction in fitness and population adaptability High mortality Low reproduction Small population Copyright © 2010 Pearson Education, Inc. Figure 14. 26

§ Irish potato is a human example of the potentially disastrous effects of low genetic diversity § In 1850 s, 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 Copyright © 2010 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. Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc. Table 14. 3

Which cause of extinction poses the most serious threat to biodiversity today? § § degradation of habitat introduction of nonnative species overharvesting effects of pollution Copyright © 2010 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. Copyright © 2010 Pearson Education, Inc.

How many square kilometers of rain forest are cut each year in South America’s

Habitat fragmentation is especially threatening to ______. § § small decomposers large plants small

Which of these terms best describes a dairy cow? § § producer primary consumer

The relationship where cleaner fish remove and consume parasites from the bodies of larger fish is known as _____. § § parasitism mutualism commensalism competition Copyright © 2010 Pearson Education, Inc.

True or False: An ecosystem is defined as all of the organisms in a

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. Copyright © 2010 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. Copyright © 2010 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 Copyright © 2010 Pearson Education, Inc.