Sustaining Biodiversity: The Species Approach 5 Sustaining Biodiversity: The Species Approach

5-1 What Are the Trends in Species Extinction? Extinction is a natural process that sometimes accelerates Background extinction Natural low rate of extinction Species extinction Local extinction Ecological extinction Biological extinction: irreversible loss

According to the UN, the Earth is in the midst of a mass extinction of life. Scientists estimate that 150-200 species of plant, insect, bird and mammal become extinct every 24 hours. This is nearly 1,000 times the “natural” or “background” rate and, say many biologists, is greater than anything the world has experienced since the vanishing of the dinosaurs nearly 65m years ago.

Case Study ─ The Passenger Pigeon: Gone Forever Once one of the world’s most abundant birds Audubon (1813): flock took 3 days to fly over Hunted to extinction by 1900 Contributing factors Habitat loss Commercial hunting Easy to kill: flew in large flocks and nested in dense colonies

Some Human Activities Are Causing Extinctions Human activity has taken over, disturbed, or polluted 60 to 80 percent of the earth’s land surface 50 percent of surface waters Current annual extinction rate 0.1 percent per year

Some Human Activities Are Causing Extinctions Projected 1.0 percent extinction rate in next 50 to 100 years may be too low Species loss rate and biodiversity losses likely to increase sharply Highly endangered biodiversity centers already exist Many biologically diverse environments have already been degraded

Science Focus: Estimating Extinction Rates Challenges Natural extinction takes a very long time Only 2 million species have been identified Scientists know little about the ecological roles of identified species Scientists strive to get better data and to improve mathematical models

Table 11_02

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

Characteristic Examples Low reproductive rate Blue whale, giant panda, rhinoceros Characteristic Examples Specialized niche Blue whale, giant panda, Everglades kite Narrow distribution Elephant seal, desert pupfish Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Fixed migratory patterns Blue whale, whooping crane, sea turtle Rare African violet, some orchids Figure 5-3 Some species have characteristics that can put them in greater danger of becoming extinct. Question: Which of these characteristics might possibly have contributed to the extinction of the passenger pigeon? Commercially valuable Snow leopard, tiger, elephant, rhinoceros, rare plants and birds Large territories California condor, grizzly bear, Florida panther Stepped Art Fig. 5-3

5-2 Why Should We Care about the Rising Rate of Species Extinction? A diversity of species is a vital part of the earth’s natural capital Reasons to prevent extinctions Instrumental value, e.g., pollination, natural pest, economically valuable products, ecotourism, genetic information, etc. Amount of time required for natural speciation to rebuild lost biodiversity

Science Focus: Where Have All the Honeybees Gone? Honeybees’ ecosystem service: pollination One-third of human food supply from insect-pollinated plants U.S. growers rent European honeybees from beekeepers Colony collapse disorder (CCD) Decline in honeybee populations Scientists seeking the cause

Pacific yew Taxus brevifolia, Pacific Northwest Ovarian cancer Rosy periwinkle Cathranthus roseus, Madagascar Hodgkin's disease, lymphocytic leukemia Rauvolfia Rauvolfia sepentina, Southeast Asia Anxiety, high blood pressure Neem tree Azadirachta indica, India Treatment of many diseases, insecticide, spermicides Foxglove Digitalis purpurea, Europe Digitalis for heart failure Cinchona Cinchona ledogeriana, South America Quinine for malaria treatment Figure 5-4 Natural capital: These plant species are examples of nature’s pharmacy. Parts of these plants (many of them found in tropical forests) are used to treat a variety of human ailments and diseases. Fig. 5-4

Are We Ethically Obligated to Prevent Premature Extinction? Species’ intrinsic (existence) value Inherent right to exist and play its ecological roles Ethical dilemma Which species should we protect? Biologists urge caution True foundation of the earth’s ecosystems and ecological processes are invisible microorganisms

How do Humans Accelerate Species Extinction? Loss of habitat is the single greatest threat to species: remember HIPPCO Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population growth and increasing use of resources Pollution Climate change Overexploitation

Asian or Indian Elephant Indian Tiger Range 100 years ago Range today Black Rhino Range in 1700 Range today African Elephant Probable range 1600 Range today Asian or Indian Elephant Former range Range today Figure 5-6 Natural capital degradation: Reductions in the habitat areas, or ranges, of four wildlife species. Question: Would you support expanding these ranges even though this would reduce the land available for human habitation and farming? Explain. (Compiled by the authors using data from International Union for the Conservation of Nature and World Wildlife Fund) Stepped Art Fig. 5-6

Some Deliberately Introduced Species Can Disrupt Ecosystems Most species introductions are beneficial Such as corn, wheat, cattle, poultry, and trees Nonnative species may have no natural controls Predators Competitors Parasites Pathogens

Some Accidentally Introduced Species Can Disrupt Ecosystems Most arrive from other continents as stowaways Example: Argentina fire ant Introduced into the U.S. in the 1930s Can overtake native ant populations Have killed deer fawns, birds, people allergic to their venom, etc.

Deliberately Introduced Species Purple loosestrife African honeybee (“Killer bee”) Kudzu Nutria European wild boar (Feral pig) Accidentally Introduced Species Figure 5-7 Some of the more than 7,100 harmful invasive (nonnative) species that, after being deliberately or accidentally introduced into the United States, have caused ecological and economic harm. Sea lamprey (attached to lake trout) Argentina fire ant Burmese python Formosan termite Zebra mussel Fig. 5-7

Case Study: Burmese Pythons Eating Their Way through the Florida Everglades Burmese and African pythons Sold as pets Dumped in Everglades by some owners Reproduce rapidly Huge appetites Feed on birds, mammals, and some reptiles Tens of thousands now in Everglades Fear of spreading to other swampy wetlands

Prevention Is the Best Way to Reduce Threats from Invasive Species Prevent them from being introduced Learn the species’ characteristics Inspect incoming goods Pass international laws to prevent transfer Require cargo ships to be free of invader organisms before entering ports Increase research Individual awareness and efforts

Figure 5-10 Individuals matter: Some ways to prevent or slow the spread of harmful invasive species. Questions: Which two of these actions do you think are the most important ones to take? Why? Fig. 5-7 Fig. 9-12, p. 202

Other Causes of Species Extinction Human population growth Overconsumption Pollution Climate change

Case Study: Polar Bears and Global Warming 20,000-25,000 in the arctic regions Primary winter food Seals found on floating ice Live on body fat during summer and fall Resume hunting when ice expands in winter Environmental impact on polar bears Shortened winter: shrinking ice Placed on threatened species list (2008)

Illegal Killing, Capturing, and Selling of Wild Species Threatens Biodiversity Poaching Wildlife smuggling For each animal smuggled many others die in transit Prevention through education Show financial benefit of preserving a species as opposed to poaching

Case Study: A Disturbing Message from the Birds Twelve percent of all bird species Threatened with extinction Species’ loss: main cause is H in HIPPCO One-third of 800 bird species in U.S. are endangered or threatened Second leading danger: intentional or accidental nonnative species’ introduction

Case Study: A Disturbing Message from the Birds Other threats Oil spills Pesticides and herbicides Lead poisoning from shotgun pellets Fishing nets Climate change Overexploitation Birds serve as environmental indicators

5-4 How Can We Protect Wild Species from Extinction from Our Activities? International treaties and national laws can help to protect species 1975 Convention on International Trade in Endangered Species (CITES) Signed by 175 countries Convention on Biological Diversity (BCD) Focuses on ecosystems Ratified by 193 countries (not the U.S.)

Case Study: The U.S. Endangered Species Act Endangered Species Act (ESA): 1973 Amended in 1982, 1985, and 1988 National Marine Fisheries Service (NMFS) Identifies and lists endangered and threatened ocean species U.S. Fish and Wildlife Service (USFWS) Identifies and lists all other endangered and threatened species

Case Study: The U.S. Endangered Species Act Federal agencies (except Defense) Forbidden from funding or authorizing projects that jeopardize endangered or threatened species 2012: 1,374 species officially listed USFWS and NMFS Prepare recovery plans Incentives for private property owners

Case Study: The U.S. Endangered Species Act ESA proponents point out reasons the agency is not a failure Species listed only when in serious danger Takes decades to help endangered species 2011: average expenditure is 8 cents per U.S. citizen

Case Study: The U.S. Endangered Species Act Ways to improve ESA Greatly increase funding Develop recovery plans more quickly When a species is first listed, establish the core of its habitat that is critical for survival and give that area the maximum protection New law needed to focus on sustaining biodiversity and ecosystem health

We Can Establish Wildlife Refuges and Other Protected Areas 1903: Theodore Roosevelt Established U.S. federal wildlife refuge at Pelican Island, Florida 2012: 555 refuges in the National Wildlife Refuge System Most are wetland sanctuaries More needed for endangered plants

Seed Banks / Botanical Gardens / Wildlife Farms Can Help to Protect Species Preserve endangered plants’ genetic material Botanical gardens and arboreta Living plants Farms to raise some endangered or threatened species for commercial sale

Zoos and Aquariums Can Protect Some Species Long-term goal Reintroducing the species into protected wild habitats Techniques for preserving endangered terrestrial species Egg pulling Captive breeding Non-feasible solutions: limited space and funds

We Can Use the Principles of Sustainability to Protect Species Actions needed to: Prevent the factors that will hasten species’ extinction Slow climate change Reduce the size and impact of our ecological footprints