Ecosystems: Diversity and Loss

Biodiversity Is a Crucial Part of the Earth’s Natural Capital Species diversity Number and variety of species Genetic diversity Variety of genes in a population Ecosystem diversity Biomes: regions with distinct climates/species Biodiversity – variety in the earth’s species Species – set of individuals who can mate and produce fertile offspring 8 million to 100 million species About 2 million identified Unidentified species are mostly in rain forests and oceans

Biodiversity Is a Crucial Part of the Earth’s Natural Capital Functional diversity Variety of processes within ecosystems Biodiversity is an important part of natural capital National Capital: Figure 4.2 Natural capital: The major components of the earth’s biodiversity—one of the planet’s most important renewable resources and a key component of its natural capital (see Figure 1-3, p. 7). Question: Why do you think we should protect the earth’s biodiversity from our actions?

Coastal mountain ranges Mississippi River Valley Major Biomes Denver Baltimore San Francisco Las Vegas St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Figure 4-4: The major biomes found along the 39th parallel across the United States show a variety of ecosystems. The differences in tree and other plant species reflect changes in climate, mainly differences in average annual precipitation and temperature. Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest Fig. 4-4, p. 81

How Does the Earth’s Life Change Over Time? Theory of evolution: explains how life on earth changes over time through changes in the genes of populations Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection)

Biological Evolution by Natural Selection Explains How Life Changes over Time Fossils Physical evidence of ancient organisms Reveal what their external structures looked like Fossil record – entire body of fossil evidence We only have fossils of 1% of all species that lived on earth Figure 4-5: This fossil shows the mineralized remains of an early ancestor of the present-day horse. It roamed the earth more than 35 million years ago. Note that you can also see fish skeletons on this fossil.

Biological Evolution by Natural Selection Biological evolution – how the earth’s life changes over time through changes in the genetic characteristics of populations Darwin – On the Origin of Species Natural selection – individuals with certain traits are more likely to survive and reproduce under a certain set of environmental conditions Huge body of evidence

Mutations and Changes in the Genetic Makeup of Populations Populations evolve by becoming genetically different Genetic variations First step in biological evolution Occurs through mutations in reproductive cells Mutations – random changes in DNA molecules Natural selection: acts on individuals Second step in biological evolution Adaptation may lead to differential reproduction Genetic resistance – ability of one or more members of a population to resist a chemical designed to kill it

Adaptation through Natural Selection Has Limits Three common myths: Fitness is reproductive success, not strength Organisms do not develop traits out of need or want There is no grand plan of nature for perfect adaptation Adaptive genetic traits must precede change in the environmental conditions A population’s reproductive capacity Species that reproduce rapidly and in large numbers are better able to adapt

How Do New Species Evolve? Speciation – one species splits into two or more species Geographic isolation First step Physical isolation of populations for a long period Figure 4.12 Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation.

How Do New Species Evolve? Reproductive isolation Mutations and natural selection in geographically isolated populations Leads to inability to produce viable offspring when members of two different populations mate

All Species Eventually Become Extinct Extinction Process in which an entire species ceases to exist Endemic species Found only in one area Particularly vulnerable to extinction Background extinction Typical low rate of extinction Mass extinction Significant rise above background level

Species Diversity Includes Variety and Abundance Number and variety of species in a given area Species richness The number of different species in a given area Species evenness Comparative number of individuals of each species present Diversity varies with geographical location The most species-rich communities Tropical rain forests Coral reefs Ocean bottom zone Large tropical lakes

Species-Rich Ecosystems Tend to Be Productive and Sustainable Species richness Increases productivity and stability or sustainability Provides insurance against catastrophe How much species richness do you think is needed?

Humans Have Disturbed Much of the Earth’s Land About 60% of the world’s major terrestrial ecosystems are being degraded The human ecological footprint is spreading across the globe Figure 7-18: Natural capital degradation: Projected status of biodiversity in 2018, resulting from ongoing threats of habitat loss and fragmentation, invasions of nonnative species, pollution, climate change, and unsustainable exploitation.

Size and Locations of Biomes Can Change Biomes are not fixed They change as the climate changes Human activities are likely to affect biome placement in the future Figure 7-19: As temperatures rose during the last 18,000 years, huge quantities of ice melted and the global climate changed. This led to shifts in the sizes and locations of several major biomes in eastern North America. Question: Based on these maps, how might you expect the sizes and locations of these biomes to change if the earth’s average atmospheric temperature rises by about 2–5 Co (4–9 Fo) during this century.

Core Case Study: Where Have All the Honeybees Gone? Bees play a key role in pollination Globally, about one third of the food supply comes from insect- pollinated plants Currently, agriculture depends heavily on a single species of bee Suffering from Colony Collapse Disorder Each year, 30-50% of colonies in Europe and the U.S. Figure 9-1: European honeybee drawing nectar from a flower.

What Role Do Humans Play in the Loss of Species and Ecosystem Services? Species are becoming extinct 100 to 1,000 times faster than they were before modern humans arrived on the earth By the end of this century, the extinction rate is expected to be 10,000 times higher than that background rate

Extinctions Are Natural but Sometimes They Increase Sharply Biological extinction No species member alive Trophic cascade Population declines or extinctions among connected species Mass extinction Many species in a short amount of time

Some Human Activities Hasten Extinctions and Threaten Ecosystem Services Background extinction rate 1 extinct species / year / 1 million species Extinction rates have risen recently Current extinction rate is at least 100 times higher than typical background rate of 0.0001%

Some Human Activities Hasten Extinctions and Threaten Ecosystem Services Rate of extinction and threats to ecosystem services likely to rise sharply in the next 50-100 years Due to harmful human impacts Biodiversity hotspots Extinction rates projected to be much higher than average Biologically diverse environments are being eliminated or fragmented

Endangered and Threatened Species Are Ecological Smoke Alarms Endangered species So few members that the species could soon become extinct Threatened species (vulnerable species) Still enough members to survive, but numbers declining May soon be endangered Figure 9-2: Endangered natural capital: These four critically endangered species are threatened with extinction, largely because of human activities. The number below each photo indicates the estimated total number of individuals of that species remaining in the wild, as of 2012.

Endangered and Threatened Species Are Ecological Smoke Alarms Regionally extinct In areas a species is normally found Functionally extinct To the point at which species can no longer play a functional role in the ecosystem Figure 9-3 Endangered natural capital: Comparison of the percentages of various types of known species that are threatened with extinction hastened by human activities (Concept 9-1). Question: Why do you think so many of the world’s amphibians are threatened with extinction?

Why Should We Care about the Rising Rate of Species Extinction? We should avoid speeding up the extinction of wild species because: Of the ecosystem and economic services they provide It can take millions of years for nature to recover from large- scale extinctions Many people believe that species have a right to exist regardless of their usefulness to us

Species Are a Vital Part of the Earth’s Natural Capital Major reasons to prevent extinctions Species provide vital ecosystem services Help keep us alive and support our economies Many species also contribute economic services Plants for food, fuel, lumber, and medicine Ecotourism Figure 9-5: Natural capital degradation. These endangered orangutans depend on a rapidly disappearing tropical forest habitat. Question: What difference will it make if human activities hasten the extinction of the orangutan?

Species Are a Vital Part of the Earth’s Natural Capital It will take 5-10 million years to regain species biodiversity after this century’s extinctions Many people believe species have an intrinsic right to exist How do we decide which species to protect? Figure 9-6: Natural capital. These plant species are examples of nature’s pharmacy. Once the active ingredients in the plants have been identified, scientists can usually produce them synthetically. The active ingredients in nine of the ten leading prescription drugs originally came from wild organisms.

Loss of Habitat Is the Single Greatest Threat to Species: Remember HIPPCO Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation

Loss of Habitat Is the Single Greatest Threat to Species Habitat fragmentation Large intact habitat divided by roads, crops, and urban development National parks and nature reserves as habitat islands Figure 9-8: Natural capital degradation: These maps reveal the reductions in the ranges of four wildlife species, mostly as the result of severe habitat loss and fragmentation and illegal hunting for some of their valuable body parts. Question: Would you support expanding these ranges even though this would reduce the land available for human habitation and farming? Explain.

We Have Moved Disruptive Species into Some Ecosystems Many species introductions are beneficial Nonnative species may have no natural: Predators, competitors, parasites, pathogens Nonnative species can crowd out native species Invasive species Figure 9-9: These are some of the estimated 7,100 harmful invasive species that have been deliberately or accidentally introduced into the United States.

Case Study: The Kudzu Vine and Kudzu Bugs Imported from Japan in the 1930s Help control soil erosion Very difficult to kill Could there be benefits of kudzu? Kudzu bug – imported from Japan Can kill Kudzu vine Also kills soybeans Figure 9-10: Kudzu has grown over this car in the U.S. state of Georgia.

Some Accidentally Introduced Species Can Disrupt Ecosystems Reproduce rapidly and are hard to kill Greatly depleted Everglades populations of: Rabbits, foxes, raccoons, opossums, and deer Argentina fire ant – introduced in the 1930s Reduced populations of native ants Painful stings can kill Pesticide spraying in 1950s and 1960s worsened conditions Tiny parasitic flies may help control fire ants

Other Causes of Species Extinctions Human population growth and overconsumption Degrading habitat Pollution Bioaccumulation can cause extinctions of species not directly affected by pollution Climate change Some species will become extinct, some will spread Figure 9-13: Bioaccumulation and biomagnification: DDT is a fat-soluble chemical that can accumulate in the fatty tissues of animals. In a food chain or web, the accumulated DDT is biologically magnified in the bodies of animals at each higher trophic level, as it was in the case of a food chain in the U.S. state of New York, illustrated here. (Dots in this figure represent DDT.) Question: How does this story demonstrate the value of pollution prevention?

Case Study: Polar Bears and Climate Change Live only in the Arctic Arctic ice is melting Decreasing polar bear habitat Polar bears must swim farther between ice Weaker females; less reproduction Figure 9-14: On floating ice in Svalbard, Norway, a polar bear feeds on its ringed seal prey. Question: Do you think it matters that the polar bear may become extinct during this century primarily because of human activities? Explain.

Illegal Killing, Capturing, and Selling of Wild Species Threatens Biodiversity Poaching and smuggling of animals and plants Animal parts Pets Plants for landscaping and enjoyment Prevention Research and education Figure 9-15: A poacher in South Africa killed this critically endangered northern white rhinoceros for its two horns. This species is now extinct in the wild. With a rhino horn worth up to $300,000 on the Asian black market, thieves have been stealing the horns from museums, antique stores, and even private collections. Question: What would you say if you could talk to the poacher who killed this animal for its horns?

Case Study: A Disturbing Message from the Birds 70% of the world’s bird species are declining Habitat loss and fragmentation of the birds’ breeding habitats Forests cleared for farms, lumber plantations, roads, and development Intentional or accidental introduction of nonnative species These species eat the birds

Case Study: A Disturbing Message from the Birds Exposure to pesticides Overexploitation For pets Birds are indicator species Respond quickly to environmental changes Birds perform critical ecosystem and economic services Extinctions could affect many other species Figure 9-17: Endangered natural capital: This endangered Attwater’s prairie chicken lives in a wildlife refuge in the U.S. state of Texas.

International Treaties and National Laws Help to Protect Species 1975 – Convention on International Trade in Endangered Species (CITES) Signed by 172 countries Convention on Biological Diversity (BCD) Focuses on ecosystems Ratified by 190 countries (not the U.S.)

Case Study: The U.S. Endangered Species Act Endangered Species Act (ESA) – 1973 and later amended in 1982, 1985, and 1988 Identify and protect endangered species in the U.S. and abroad National Marine Fisheries Service for ocean species U.S. Fish and Wildlife Service for all others

Case Study: The U.S. Endangered Species Act Forbids federal agencies (except Defense) from funding or authorizing projects that jeopardize endangered or threatened species In 2012, 1,394 species officially listed Offer incentives to private property owners to help

Case Study: The U.S. Endangered Species Act Is the ESA a failure? Species are listed only when in serious danger Conditions for more than half of listed species are stable or improving Budget is about 57 cents per U.S. citizen Figure 9-19: The American bald eagle has been removed from the U.S. endangered species list. Here, an eagle is about to catch a fish in its powerful talons.

The Lacey Act of 1900 (United States) Conservation law in the United States that prohibits trade in wildlife, fish, and plants that have been illegally taken, possessed, transported, or sold.

We Can Establish Wildlife Refuges and Other Protected Areas In 1903, Theodore Roosevelt established the first federal wildlife refuge Pelican Island, Florida Wildlife refuges Most are wetland sanctuaries More needed for endangered plants Are not immune from disturbance Figure 9-20: The Pelican Island National Wildlife Refuge in Florida was America’s first National Wildlife Refuge.

Seed Banks, Botanical Gardens, and Wildlife Farms Can Help Protect Species Preserve genetic material of endangered plants Botanical gardens and arboreta Living plants Farms can raise organisms for commercial sale Zoos/Aquariums: Techniques for preserving endangered terrestrial species Egg pulling Captive breeding Artificial insemination Embryo transfer Use of incubators Cross-fostering

The Precautionary Principle Act to prevent or reduce harm when preliminary evidence indicates acting is needed Species are the primary components of biodiversity Should we focus on the preservation of species or the preservation of ecosystems?