Transcript CH. 8 Notes
Sustaining Biodiversity: The Species Approach Chapter 8 The Passenger Pigeon: Gone Forever Once most common bird in N. America- Extinct in 1914 Humans were responsible (huge flocks, narrow colonies = easy to kill- stool pigeons) Why they were hunted (food, feathers, fertilizer) Extinction Types of Species Extinction Local extinction- like it sounds Ecological extinction - too few to play ecological role Biological extinction - all gone everywhere Some Prematurely Extinct Species Passenger pigeon Great auk Dodo Dusky seaside sparrow Aepyornis (Madagascar) Fig. 8-2, p. 154 Endangered and Threatened Species Endangered species could soon become extinct over some or all of its range Threatened species still abundant, but likely to become endangered Fig. 8-3, p. 156 More Endangered and Threatened Species Florida manatee Devil's hole pupfish Ghost bat (Australia) Northern spotted owl (threatened) Snow leopard (Central Asia) Gray wolf Florida panther Symphonia (Madagascar) Black-footed ferret California condor Black lace cactus Black rhinoceros (Africa) Bannerman's turaco (Africa) Utah prairie dog (threatened) Oahu tree snail Characteristics of Extinction-Prone Species Characteristic “The first animal species to go are the big, the slow, the tasty and those with valuable parts such as tusks and skins.” Low reproductive rate (K-strategist) Blue whale, giant panda, rhinoceros Specialized niche Blue whale, giant panda, Everglades kite Narrow distribution Many island species, elephant seal, desert pupfish Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Fixed migratory patterns Blue whale, whooping crane, sea turtles Rare Many island species, African violet, some orchids Commercially valuable Snow leopard, tiger, elephant, rhinoceros, rare plants and birds Large territories California condor, grizzly bear, Florida panther E.O.Wilson Fig. 8-4, p. 157 Examples Percentages of Various Types of Organisms Threatened with Extinction by Human Activities 34% (51% of freshwater species) Fish 24% Mammals 20% Reptiles Plants Birds 14% 12% Fig. 8-5, p. 157 Problems Estimating Extinction Rates Extinction not easily documented over time Many species remain unidentified Little is known about most identified species Estimating Extinction Rates Estimates from records and fossils Species-area relationship: on average, a 90% habitat loss causes the extinction of 50% of the species living in that habitat Models to estimate risks of extinction for a particular species Estimates of extinction rates can vary depending on available data and what assumptions are used Human Impacts on Extinction Rates Humans have greatly accelerated extinction rates (1,000 10,000x) Conservative estimates of 0.1% to 1% per year. Due to human population increases Extinction rates higher in biodiversity “hot spots” Speciation crisis (humans limiting long-term recovery of biodiversity via impacts on ecosystems, colonization sites for emergence of new species) Inadequate estimations of extinction rates Precautionary strategy Importance of Wild Species May take nature 5 million years to replace the species that may be lost in the 21st century Instrumental value- ecological services, food, fuel, lumber, paper, medicine Genetic information- better ability to adapt to changing enviro. conditions Recreational pleasure and ecotourismlion living in Kenya generates > $.5 million over 7 years elephant worth about $1 million over 60 yrs Intrinsic or existence value - Do species have an inherent right to exist? Even small organisms can be important Nature’s Pharmacy 9 of 10 leading Rx drugs originated from wild species < 1% of flowering plants in tropical forests studied for medicinal properties Fig. 8-7, p. 158 Causes of Premature Extinction “HIPPCO” Habitat destruction and fragmentation Invasive (alien) species Population growth (humans) Pollution Climate Change Overharvesting Extinction Threats from Habitat Loss and Degradation Importance of habitats Deforestation- particularly tropical forests Destruction of wetlands and coral reefs Endemic species- found nowhere else on earth “Habitat islands”- surrounded by different habitat Habitat fragmentation - continuous area divided into small, scattered patches “Message” from the birds - 70% are declining, 1/6 threatened with extinction Birds are indicator species Threatened Species of U.S. Songbirds Cerulean warbler Florida scrub jay Sprague’s pipit California gnatcatcher Bichnell’s thrush Kirtland’s warbler Blacked-capped vireo Henslow’s sparrow Golden-cheeked warbler Bachman’s warbler Reduced Ranges Asian or Indian Elephant Indian Tiger Former range Range today (34,000–54,000 left) Range 100 years ago Range today (about 2,300 left) See Fig. 8-9, p. 161 Deliberately Introduced Species Purple looselife European starling Marine toad Water hyacinth African honeybee (“Killer bee”) Japanese beetle Nutria Hydrilla Salt cedar (Tamarisk) European wild boar (Feral pig) Fig. 8-10, p. 163 Accidentally Introduced Species Sea lamprey (attached to lake trout) Formosan termite Argentina fire ant Zebra mussel Brown tree snake Asian long-horned beetle Eurasian muffle Common pigeon (Rock dove) Asian tiger mosquito Gypsy moth larvae Fig. 8-10, p. 163 Kudzu Fig. 8-11, p. 164 Fire Ant Invasion Currently as far north as CA and the Bay Area 1918 2000 Reducing Threats from Nonnative Species Cost U.S. Taxpayers $137 billion /yr Threaten 1/2 critical species in US (95% in Hawaii) Prevention is best Identify the characteristics of nonnative species Identify vulnerable ecosystems Thoroughly inspect imports Establish appropriate international laws Discharge of ballast waters from ships Characteristics of Successful Invader Species and Vulnerable Ecosystems Characteristics of Successful Invader Species Characteristics of Ecosystems Vulnerable to Invader Species • High reproductive rate, short generation time (r-selected species) • Similar climate to habitat of invader • Pioneer species • Absence of predators on invading species • Long lived • High dispersal rate • Release growthinhibiting chemicals into soil • Generalists • High genetic variability • Early successional systems • Low diversity of native species • Absence of fire • Disturbed by human activities Fig. 8-13, p. 165 Extinction Threats from Poaching Profits of poaching Mt. gorilla = $150K; panda pelt = $100K; chimp = $50K; rhino horn = $28k /Kg (most live animals die in transit) Causes of poaching: food, fur, pets, traditional medicines, trophies, eliminating pests, etc. Bushmeat Illegal pets and decorative plants orchids can fetch up to $5K; saguaro cactus $15K > 60 bird species are endangered or threatened due to wild bird trade keeping a bird indoors for more than 10 yrs doubles chances of getting lung cancer Irony of collecting exotics Attempts to control poaching Bushmeat Fig. 8-17, p. 169 Extinction Threats from Climate Change and Pollution Greenhouse effect Pesticide threats- decline in honeybees, birds & fish DDT biomagnification (bioaccumulation) Biomagnification of DDT DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm Fat soluble chemicals increase in concentration at higher levels of food web DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, or 3 ppt Fig. 8-15, p. 166 Protecting Wild Species International Treaties Convention on International Trade in Endangered Species (CITES) • signed by 166 countries- lists 900 endangered species that cannot be commercially traded • restricts international trade of 29,000 threatened species • limited impact due to spotty enforcement, ability for countries to except themselves Convention on Biological Diversity (CBD) • legally binds governments to reverse decline of biodiversity • ratified by 190 countries (not USA)- No severe penalties Protecting Wild Species - U.S. Federal Laws Important on APES Exam Lacey Act (1900) - prohibits transporting live or dead wild animals or parts across state borders w/out federal permit. Endangered Species Act (ESA- 1973)- one of world’s toughest & controversial enviro laws • goal is to identify & protect endangered species in USA & abroad • NMFS / USFWS responsible for identifying and listing endangered & threatened species • illegal for Americans to buy any product made from protected species • species cannot be killed, collected or injured in US • $100k fines and 1 year prison terms for offenses • protection extended to threatened & endangered foreign species • In 2005 there were1,260 protected species (many critical species not yet listed) Establishing critical habitatsESA requries protection of critical habitat for recovery of listed species. Due to lack of funds, only 33% of listed species have critical habitat established Since 2001, gov has stopped listing new species & designating critical habitats unless mandated by court order Endangered Species Act (continued) Habitat conservation plans• 1982 amendment to ESA allows landowners, developers or loggers to destroy critical habitat if they take steps to protect members of species (set asides, paying to relocate, or buying suitable habitat elsewhere • criticized as loophole - many plans approved without scientific evaluation ESA and commercial shipping- all commercial wildlife shipments must leave or enter US via one of nine designated ports • 60 USFWS inspectors examine only 25% of 90,000 yearly shipments • violators often not prosecuted and pay only small fine Confiscated Products From Endangered Species Due to sparse $$ and inspectors, < 10% of illegal wildlife trade in US is discovered Biodiversity Hot Spots in the US Top Six Hot Spots 1 Hawaii 2 San Francisco Bay area 3 Southern Appalachians 4 Death Valley 5 Southern California 6 Florida Panhandle 2 4 3 5 6 1 Concentration of rare species Low Moderate High Protecting Marine Species Role of the Endangered Species Act Threats from litter- plastic threatens millions of marine species “Pacific Garbage Dump” - Nightline Video - click here Threatened sea mammals- whales, seals, sea lions Threatened sea turtles- Need more knowledge of marine biodiversity Difficulty enforcing international treaties • World’s 8 major sea turtle species are endangered or threatened• Poaching and threats from fishing nets Endangered Sea Turtles World’s 8 major sea turtle species are endangered or threatened- What Can We Do to Protect Species? What Can You Do? Protecting Species • Do not buy furs, ivory products, and other materials made from endangered or threatened animal species. • Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics. • Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild. • Do not buy orchids, cacti, and other plants that are taken from the wild. Fig. 8-20, p. 174