9-3 How do Humans Accelerate Species Extinction?
Concept 9-3The 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.
Population _____________ _______________ resource use _____________________ natural capital _________________ growth Rising Undervaluing 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 Figure 9.9: This figure illustrates both the underlying and direct causes of depletion and extinction of wild species resulting from human activities (Concept 9-3) (see Figure 1-9, p. 13). The biggest cause is habitat loss, degradation, and fragmentation. This is followed by the deliberate or accidental introduction of harmful invasive (nonnative) species into ecosystems. Question: What are two direct causes that are specifically related to each of the underlying causes? Habitat loss Pollution Commercial hunting and poaching Climate change Habitat degradation and fragmentation Overfishing Sale of exotic pets and decorative plants Introduction of nonnative species 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 _____________________ Habitat destruction, degradation, and fragmentation Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation HIPPCO According to researchers, the greatest threat to wild 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, isolated patches or ________________________ Divisions may be caused by roads, logging operations, crop fields, and urban development habitat divided habitat islands Habitat Fragmentation
Habitat fragmentation can Decrease tree ____________ in forests Block migration __________________ _________________ populations Create _________________ to colonization Inhibits finding ___________ and _____________ Isolated populations may be more vulnerable to ___________________ ___________________ species ____________________ ____________________ events (storms, fires) cover routes Divide barriers food mates predators Competitor Disease Catastrophic 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 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 _____ __________________ predators, competitors, parasites, or pathogens that would help to control their numbers in their original habitats no natural Deliberately Introduced Species
Purple loosestrife European starling African honeybee (Killer bee) Nutria Salt cedar (Tamarisk) Figure 9.11: These are some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Marine toad (Giant toad) Water hyacinth 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) Figure 9.11: These are some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. 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 U.S. The vine that ate the South grows rapidly and is difficult to kill._______________ anything in its path erosion engulfs Kudzu Taking Over an Abandoned House in Mississippi, U.S.
Figure 9.12: Kudzu has taken over this abandoned house in the U.S. state of Mississippi. The vine, which can grow 5 centimeters (2 inches) per hour, was deliberately introduced into the United States for erosion control. Digging it up and burning it do not halt its spread. Grazing goats and repeated doses of herbicides can destroy it, but goats and herbicides also destroy other plants, and herbicides can contaminate water supplies. Scientists have found a common fungus that can kill kudzu within a few hours, apparently without harming other plants, but they need to investigate any harmful side effects it may have. Fig. 9-12, p. 201 Case Study: The Kudzu Vine
Could there be benefits of kudzu? Fiber for making _____________ (could end up saving trees) Kudzu starch powder reduces desire for alcohol Edible, high levels of vitamins _____ and _____ Japan actually maintains a kudzu farm in Alabama and ships the starch to Japan paper A C Another deliberately introduced species that became invasive was the African ___________________
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 ______________ Carries parasites that cause ___________________ and other human diseases land snail crops meningitis Some Accidentally Introduced Species Can Also Disrupt Ecosystems
Argentina fire ant: 1930s Accidentally introduced in Alabama 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 conditions .genetic __________________ 2009: tiny parasitic flies may help control fire ants shiploads resistance Fight Between a Python and Alligator
Pythonssold as _______________. Accidentally introduced to the Florida ____________________ pets Everglades Figure 9.13: This huge python and an American alligator were in a life-or-death struggle in the Florida Everglades. After a 10-hour battle the alligator killed the snake by taking it underwater and drowning it. However, in some struggles, these snakes kill and eat the alligatorstheir only natural predator in the Everglades. Fig. 9-13, p. 202 Prevention Is the Best Way to Reduce Threats from Invasive Species
Prevent them from becoming ________________ Learn the characteristics of the species Set up research programs Try to find natural ways to control them International treatiesban transfers between countries Public education established What Can You Do? Controlling Invasive Species
Figure 9.14: Individuals matter. Here is a list of 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? Why? Which of these actions do you plan to take? 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, degraded, and fragmented vast areas of wildlife habitat Pollution________________ have killed honeybees (crop pollinators) , many birds and fish Climate change - ______________ temperatures and melting ice may drive to of all _______ animals and plants to extinction footprint pesticides higher land Other Causes of Species Extinction (2)
Toxins can be _____________ through a food chain Organisms at _____________ trophic levels are exposed to ALL of the toxins encountered by lower levels Bioaccumulation biomagnified higher Case Study: Where Have All the Honeybees Gone?
Honeybees are responsible for pollinating______ of insect-pollinated plants Helps to produce _______ of the human food supply 2006 studies reported a______ drop in honeybee populations Dying due to Pesticides? Parasites? Viruses, fungi, bacteria? Microwave radiation cell phones? 80% 1/3 30% Case Study: Where Have All the Honeybees Gone?
In 2008, the U.S. had a record loss of ______ of their commercial honeybee colonies 1/3 of the deaths were due to colony _____________ _______________ (CCD) in which most or all of the adult worker bees mysteriously _______________ Suspected causes Parasites Fungus , virus, bacteria Pesticides Poor nutrition and stress caused by _____________ diets and ______________ around the country 36% collapse disorder vanish artificial moving Review Questions! What does HIPPCO stand for?
Why are nonnative species potentially harmful? The process of a toxin, like DDT, moving and accumulating through food chains is called Habitat loss Pollution Invasive species Climate change Population growth Overexploitation They may have no natural predators or other factors to limit their growth Biomagnification or bioaccumulation