Transcript 9.3 Notes
9-3 How do Humans Accelerate Species Extinction? • Concept 9-3 The greatest threats to any species are (in order) loss or degradation of its habitat, harmful invasive species, human population growth, pollution, climate change, and overexploitation. • There are four underlying causes of species extinction that result for human activities…. • • • • growth Population _____________ _______________ resource use Rising Undervaluing _____________________ natural capital Poverty _________________ Natural Capital Degradation Causes of Depletion and Extinction of Wild Species Underlying Causes • Population growth • Rising resource use • Undervaluing natural capital • Poverty Direct Causes • Habitat loss • Habitat degradation and fragmentation • Introduction of nonnative species • Pollution • Climate change • Overfishing • Commercial hunting and poaching • Sale of exotic pets and decorative plants • Predator and pest control Fig. 9-9, p. 198 Loss of Habitat Is the Single Greatest Threat to Species: Remember HIPPCO • Biodiversity researchers summarize the most important direct causes of extinction using the acronym _____________________ HIPPCO • • • • • • Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation • According to researchers, the greatest threat to wild habitat species is ________________ loss, degradation, and fragmentation • Ex: Polar bears are losing the ice beneath their feet • Habitat fragmentation – occurs when large, intact areas of habitat are ________________ into smaller, divided “habitat islands” isolated patches or ________________________ • Divisions may be caused by roads, logging operations, crop fields, and urban development Habitat Fragmentation • Habitat fragmentation can… • • • • • Decrease tree ____________ in forests cover routes Block migration __________________ Divide _________________ populations Create _________________ to colonization barriers Inhibits finding ___________ and _____________ food mates • Isolated populations may be more vulnerable to… • • • • predators ___________________ ___________________ species Competitor ____________________ Disease ____________________ events (storms, fires) Catastrophic Indian Tiger Range 100 years ago Range today African Elephant Probable range 1600 Range today Black Rhino Range in 1700 Range today Asian or Indian Elephant Former range Range today Stepped Art Fig. 9-10, p. 199 Some Deliberately Introduced Species Can Disrupt Ecosystems • Most species introductions are beneficial • • • • • Food Shelter Medicine Aesthetic enjoyment Pest control • But nonnative species may have _____ no __________________ natural predators, competitors, parasites, or pathogens that would help to control their numbers in their original habitats Deliberately Introduced Species Purple loosestrife European starling African honeybee (“Killer bee”) Nutria Salt cedar (Tamarisk) Marine toad (Giant Water hyacinth toad) Japanese beetle Hydrilla European wild boar (Feral pig) Fig. 9-11a, p. 200 Accidentally Introduced Species Sea lamprey (attached to lake trout) Argentina fire ant Brown tree snake Eurasian ruffe Common pigeon (Rock dove) Formosan termite Zebra mussel Asian long-horned beetle Asian tiger mosquito Gypsy moth larvae Fig. 9-11b, p. 200 Case Study: The Kudzu Vine • Sounds like “CUD-zoo” • Deliberately imported from Japan in the 1930s to help prevent ______________ in the southeastern erosion U.S. • “ The vine that ate the South” – grows rapidly and is engulfs difficult to kill…._______________ anything in its path Kudzu Taking Over an Abandoned House in Mississippi, U.S. Fig. 9-12, p. 201 Case Study: The Kudzu Vine • Could there be benefits of kudzu? • Fiber for making _____________ (could end up saving paper trees) • Kudzu starch powder reduces desire for alcohol • Edible, high levels of vitamins _____ and _____ A C • Japan actually maintains a kudzu farm in Alabama and ships the starch to Japan • Another deliberately introduced species that land became invasive was the African ________ ___________ snail • Imported to Brazil as a cheap substitute for conventional escargot • When export prices for escargot fell, breeder dumped the imported snails into the wild • Devours many food ______________ crops • Carries parasites that cause ___________________ and meningitis other human diseases Some Accidentally Introduced Species Can Also Disrupt Ecosystems • Argentina fire ant: 1930s • Accidentally introduced in Alabama shiploads • May have been on ________________ of lumber or imported coffee • Reduced populations of native ants • Painful stings can kill • Pesticide spraying in 1950s and 1960s worsened resistance conditions ….genetic __________________ • 2009: tiny parasitic flies may help control fire ants Fight Between a Python and Alligator Pythons…sold as _______________. pets Accidentally introduced to the Florida ____________________ Everglades Fig. 9-13, p. 202 Prevention Is the Best Way to Reduce Threats from Invasive Species • Prevent them from becoming ________________ established • Learn the characteristics of the species • Set up research programs • Try to find natural ways to control them • International treaties…ban transfers between countries • Public education What Can You Do? Controlling Invasive Species Fig. 9-14, p. 203 Other Causes of Species Extinction (1) • Human population growth and overconsumption have greatly expanded the human ecological ________________ …which has eliminated, footprint degraded, and fragmented vast areas of wildlife habitat • Pollution…________________ have killed honeybees pesticides (crop pollinators) , many birds and fish • Climate change - ______________ temperatures and higher land animals melting ice …may drive ¼ to ½ of all _______ and plants to extinction Other Causes of Species Extinction (2) • Toxins can be _____________ “biomagnified” through a food chain • Organisms at _____________ higher trophic levels are exposed to ALL of the toxins encountered by lower levels • “Bioaccumulation” Case Study: Where Have All the Honeybees Gone? 80% of • Honeybees are responsible for pollinating ______ insect-pollinated plants • Helps to produce _______ 1/3 of the human food supply 30% drop in honeybee • 2006 studies reported a ______ populations • Dying due to • Pesticides? • Parasites? • Viruses, fungi, bacteria? • Microwave radiation – cell phones? Case Study: Where Have All the Honeybees Gone? 36% • In 2008, the U.S. had a record loss of ______ of their commercial honeybee colonies • 1/3 of the deaths were due to colony _____________ collapse _______________ (CCD) in which most or all of the disorder vanish adult worker bees mysteriously _______________ • Suspected causes • • • • Parasites Fungus , virus, bacteria Pesticides artificial Poor nutrition and stress caused by _____________ moving diets and ______________ around the country Review Questions! • What does HIPPCO stand for? Habitat loss Invasive species Population growth Pollution Climate change Overexploitation • Why are nonnative species potentially harmful? They may have no natural predators or other factors to limit their growth • The process of a toxin, like DDT, moving and accumulating through food chains is called… Biomagnification or bioaccumulation