Passenger pigeon hunted to extinction by 1900

Commercial hunters used a "stool pigeon”

Geological record shows five mass extinctions

Human activities: hastening more extinctions?

We are degrading and destroying biodiversity in many parts of the world, and these threats are increasing.

Species are becoming extinct 100 to 1,000 times faster than they were before modern humans arrived on the earth (the background rate), and by the end of this century, the extinction rate is expected to be 10,000 times the background rate.

The extinction of the Passenger Pigeon had two major causes: commercial exploitation of pigeon meat on a massive scale[25] and loss of habitat.[77]

Human activity has disturbed at least half of the earth’s land surface• Fills in wetlands• Converts grasslands and forests to crop

fields and urban areas

Degraded aquatic biodiversity

Background extinction- The ongoing extinction of individual species due to environmental or ecological factors such as climate change, disease, loss of habitat, or competitive disadvantage in relation to other species. Background extinction occurs at a fairly steady rate over geological time and is the result of normal evolutionary processes, with only a limited number of species in an ecosystem being affected at any one time.

Background extinction rate, also known as ‘normal extinction rate’, refers to the standard rate of extinction in earth’s geological and biological history before humans became a primary contributor to extinctions. This is primarily the pre-human extinction rates during periods in between major extinction events.

Mass extinction: causes• Poorly understood, but involve global changes in

environmental conditions.

Levels of species extinction• Local extinction, or extirpation- Local extinction,

or extirpation, is the condition of a species (or other taxon) which ceases to exist in the chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.

Ecological extinction- is defined as “the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species.”[1]

Ecological extinction stands out because it is the interaction ecology

• Biological extinction- extinction is the end of an organism or of a group of organisms (taxon), normally a species. 

Habitat destruction Over-hunting (extirpation, poaching, etc) Pollution of water, land, and air (global

warming appears to be causing harm to some species, especially amphibians). 

Habitat fragmentation (isolating tiny populations, preventing animals from finding mates). 

Endangered species – so few individual survivors that could be soon become extinct.• International Union for the Conservation of Nature

(IUCN), or the World Conservation Union. Since 1960, published Red List In 2007, listed 16, 306 animals and plants that are in

danger of extinction—60% higher than in 1995.

Threatened species - threatened species are any species which are vulnerable to endangerment in the near future.

Grizzly Grizzly bearbear

Kirkland’s Kirkland’s warblerwarbler

Knowlton Knowlton cactuscactus

Florida Florida manateemanatee

African African elephantelephant

Utah prairie Utah prairie dogdog

Swallowtail Swallowtail butterflybutterfly

Humpback Humpback chubchub

Golden lion Golden lion tamarintamarin

Siberian Siberian tigertiger

Giant Giant pandapanda

Black-footed Black-footed ferretferret

Whooping Whooping cranecrane

Northern Northern spotted owlspotted owl

Blue whaleBlue whale

Mountain Mountain gorillagorilla

Florida Florida pantherpanther

California California condorcondor

Hawksbill Hawksbill sea turtlesea turtle

Black Black rhinocerosrhinoceros

Figure 9.4Figure 9.4Endangered natural Endangered natural capitalcapital. . SSome species that ome species that are endangered or are endangered or threatened with premature threatened with premature extinction largely because of extinction largely because of human activities. Almost human activities. Almost 30,000 of the world’s species 30,000 of the world’s species and roughly 1,300 of those in and roughly 1,300 of those in the United States are the United States are officially listed as being in officially listed as being in danger of becoming extinct. danger of becoming extinct. Most biologists believe the Most biologists believe the actual number of species at actual number of species at risk is much larger.risk is much larger.

Fixed migratory patterns

Blue whale, whooping crane, sea turtle

Feeds at high trophic level

Bengal tiger, bald eagle, grizzly bear

Narrow distribution

Elephant seal, desert pupfish

Commercially valuable

Snow leopard, tiger, elephant, rhinoceros, rare plants and birds

Low reproductive rate (K-strategist)

Blue whale, giant panda, rhinoceros

Characteristic Examples

Rare African violet, some orchids

Large territories

California condor, grizzly bear, Florida panther

Specialized niche

Blue whale, giant panda, Everglades kite

Figure 9.5Characteristics of species that are prone to ecological and biological extinction.

Three problems• Hard to document due to length of time• Only 1.8 million species identified• Little known about nature and ecological roles

of species identified

Document little changes in DNA• Suggests species survive for 1 to 10 million

years before going extinct.

Use species–area relationship• On average, 90% loss of habitat results in a

50% loss of species living in that habitat.

Mathematical models

We should prevent the premature extinction of wild species because of the economic and ecological services they provide and because they have a right to exist regardless of their usefulness to us.

“It will take 5-10 million years for natural speciation to rebuild the biodiversity we are likely to destroy during your lifetime.”

1989 international treaty against poaching elephants

Poaching on the rise

Track area of poaching through DNA analysis of elephants

Elephants damaging areas of South Africa: Should they be culled?

Intrinsic value, or existence value • Species have an inherent right to exist and

play their ecological roles, regardless of their usefulness to us.

Edward O. Wilson: biophilia phenomenon

Biophobia

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.

Habitat destruction, degradation, and fragmentation

Invasive (nonnative) species Population and resource use growth Pollution Climate change Overexploitation

Figure 9.11Figure 9.11Natural capital degradation: Natural capital degradation: reductions in the ranges of four reductions in the ranges of four wildlife species, mostly as the wildlife species, mostly as the result of habitat loss and result of habitat loss and hunting. What will happen to hunting. What will happen to these and millions of other these and millions of other species when the world’s human species when the world’s human population doubles and per population doubles and per capita resource consumption capita resource consumption rises sharply in the next few rises sharply in the next few decades? decades? Question: Question: Would you Would you support expanding these ranges support expanding these ranges even though this would reduce even though this would reduce the land available for people to the land available for people to grow food and live on? Explain. grow food and live on? Explain. (Data from International Union (Data from International Union for the Conservation of Nature for the Conservation of Nature and World Wildlife Fund)and World Wildlife Fund)

Globally, habitat loss, greatest in temperate biomes, pace picking up in tropics.

Endemic species• Hawaii, the extinction capital

of America—63% of species at risk.

Habitat islands

Habitat fragmentation

The Bali Mynah is distributed and endemic to the island of Bali, where it is the island's only surviving endemic species.  This rare bird was discovered in 1910 and is one of the world's most critically endangered birds.   In fact, it has been hovering immediately above extinction in the wild for several years.

Numbers Location Reason(s)75% of birds species Sumatra’s lowland

forestsLumber and palm plantations, used for biofuels

115 bird species Brazil Burning/clearing of rainforests for farms and ranches; 93% loss of Atlantic coastal rainforest; clearing of savannah-like cerrado for soybean plantations

30% of bird species, 70% of grassland species

North America Habitat loss and fragmentation of breeding habitat; replaced by roads and other developments.

28% of species Worldwide Introduction of non-native bird-eating species

52 of 388 parrot species

Worldwide Pet trade

23 Seabirds Worldwide Bycatch from commercial fishing; pollution

40% of waterbirds Worldwide Loss of wetlands

Seabirds caught and drown in fishing equipment

Migrating birds fly into power lines, communication towers, and skyscrapers

Other threats• Oil spills• Pesticides• Herbicides• Ingestion of toxic lead shotgun pellets

Greatest new threat: Climate change

Environmental indicators• Live in every climate and biome• Respond quickly to environmental changes• Easy to track

Economic and ecological services

Cerulean warblerCerulean warbler Sprague’s pipitSprague’s pipit Bichnell’s thrushBichnell’s thrush Black-capped Black-capped vireovireo

Golden-cheeked Golden-cheeked warblerwarbler

Florida scrub jayFlorida scrub jay California California gnatcatchergnatcatcher

Kirtland's Kirtland's warblerwarbler

Henslow's Henslow's sparrowsparrow

Bachman's warblerBachman's warbler

Figure 9.13Figure 9.13The 10 most threatened species of U.S. songbirds. Most of these species are vulnerable The 10 most threatened species of U.S. songbirds. Most of these species are vulnerable because of habitat loss and fragmentation from human activities. An estimated 12% of because of habitat loss and fragmentation from human activities. An estimated 12% of the world’s known bird species may face premature extinction due mostly to human the world’s known bird species may face premature extinction due mostly to human activities during this century. (Data from National Audubon Society)activities during this century. (Data from National Audubon Society)

Vultures poisoned from diclofenac in cow carcasses

More wild dogs eating the cow carcasses

More rabies spreading to people

Figure 9.14Figure 9.14Some of the more than 7,100 harmful invasive (nonnative) species that have been Some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States.deliberately or accidentally introduced into the United States.

Imported from Japan in the 1930s to control soil erosion.

“ The vine that ate the South”

Could there be benefits of kudzu?

Argentina fire ant: 1930s• Pesticide spraying in 1950s and 1960s

worsened conditions Wiped out competitor ant species and made

them more pesticide resistant.

Burmese python

Population growth

Overconsumption

Pollution

Climate change

Pesticides• DDT: Banned in the U.S. in 1972

Bioaccumulation

Biomagnification

Poaching and smuggling of animals and plants• Animal parts• Pets• Plants for landscaping and enjoyment

When commercially valuable species become endangered, black market prices soar.

Prevention: research and education

We can use existing environmental laws and treaties and work to enact new laws designed to prevent species extinction and protect overall biodiversity.

We can help to prevent species extinction by creating and maintaining wildlife refuges, gene banks, botanical gardens, zoos, and aquariums.

Concept 9-4C According to the precautionary principle, we should take measures to prevent or reduce harm to the environment and to human health, even if some of the cause-and-effect relationships have not been fully established, scientifically.

Gene or seed banks• Preserve genetic material of endangered

plants

Botanical gardens and arboreta• Living plants

Farms to raise organisms for commercial sale

Techniques for preserving endangered terrestrial species• Egg pulling• Captive breeding• Artificial insemination• Embryo transfer• Use of incubators• Cross-fostering

Limited space and funds

Critics say these facilities are prisons for the organisms