Sustaining Biodiversity: The Species Approach

Sustaining Biodiversity: The Species Approach

Chapter 9

Core Case Study: The Passenger Pigeon: Gone Forever

Passenger pigeon hunted to extinction by 1900

Commercial hunters used a "stool pigeon”

Archeological record shows five mass extinctions

Human activities: hastening more extinctions?

9-1 What Role Do Humans Play in the Premature Extinction of Species?

1) Human activities are destroying and degrading biodiversitya) 2005 Millennium Ecosystem Assessment: We have disturbed at least 50% up to 83%b) Disturbances eliminate species by destroying or degrading habitat

2) Extinctions are naturala) Background: continuous low level extinctions

b) Extinction rate: percentage of species that go extinct within a certain time period (page 185)

c) Biodiversity is determined by extinction & speciation

d) Mass extinction: Loss of large number of species in a short period of time

e) Probably 5 mass extinctions killing 50-95%, recovery occurs, but requires millions of years

f) Possible causes on page 185

g) 3 levels of extinction1. Local: lost to one area, but found other places2. Ecological: so few exist it no longer plays its role in the ecosystem3. Biological: No longer found anywhere

3) Human activities cause premature extinctiona) Humans have accelerated extinction as they used resources, killed for food and destroyed habitatb) We are pushing the rate to 1% per year

Extinctions Are Natural but Sometimes They Increase Sharply

c) This rate will lead to at least ¼ of the species extinct by 2050.

d) May be conservative rate because1. both the rate and species loss are likely to increase during the next 50 years2. current and projected rates are much higher than the global average in some parts of the world 3. We are degrading, eliminating, fragmenting and simplifying many diverse environments

e) This loss could cause an increase in number of opportunistic individuals (weeds, pests, rodents)

4) Endangered and Threatened Species Are Ecological Smoke Alarms (page 187)

a)Endangered: so few individual survivors that the species could soon become extinct

b)Threatened: still abundant, but numbers are declining & are likely to become endangered

c)World Conservation Union (IUCN): Publishes the Red list: list of the world’s threatened species

d)Probably underestimates actual number

www.iucnredlist.org

e) Certain Characteristics make organisms more vunerable

f) Behavioral characteristics: large groups, foraging around humans,

g) Fig 9.6 shows % of types of species threatened

Fig. 9-4, p. 194

Science Focus: Estimating Extinction Rates Is Not Easy (page 188)

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

Use species–area relationship

Mathematical models

Science Focus: Using DNA to Reduce Illegal Killing of Elephants for Their Ivory (Page 191)

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?

9-2 Why Should We Care about Preventing Premature Species Extinction?

1) Species are a vital part of the earth’s capitala) It takes millions of years to replace extinct organismsb) Instrumental Value: Usefulness to usc) 2 types:

1. Use value: economic goods and services, ecological services, recreation, scientific information & continuation of services for the future. (page 190)


2. Instrumental value: non-use

existence value, aesthetic value, bequest value & ecological value (page 190-191)

2) Are we ethically obligated to prevent extinction?a) Intrinsic (existence) value: has a right to exist & play its role. (yes?)b) Genetic value: we should not erase genetic combinationsc) Biophilia: inherent genetic kinship with natural world


(shown by human love of nature, zoos, camping)d) Biophobia: fear of wildlifee) Some vary by type of organism (kill pests, protect bears)

Science Focus: Why Should We Care about Bats? (page 192)

Vulnerable to extinction• Slow to reproduce

• Human destruction of habitats

Important ecological roles• Feed on crop-damaging nocturnal insects

• Pollen-eaters

• Fruit-eaters

Unwarranted fears of bats

9-3 How do Humans Accelerate Species Extinction?

1) HIPPCO: (page 193)a) Habitat destructionb) Invasive speciesc) Population growthd) Pollutione) Climate changef) Overexploitation

2) Habitat Island: surrounded by different habitat

3) Habitat fragmentation: divides large habitats into smaller ones

Science Focus: Studying the Effects of Forest Fragmentation on Old-Growth Trees

Page 195

Tropical Biologist Bill Laurance, et al.

How large must a forest fragment be in order to prevent the loss of rare trees?

Case Study: A Disturbing Message from the Birds Page 195

Habitat loss and fragmentation of the birds’ breeding habitats• Forests cleared for farms, lumber plantations, roads, and

development Intentional or accidental introduction of nonnative species

• Eat the birds 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 Economic and ecological services

Science Focus: Vultures, Wild Dogs, and Rabies: Unexpected Scientific Connections

Page 197 Vultures poisoned from diclofenac in cow

carcasses

More wild dogs eating the cow carcasses

More rabies spreading to people


4) Deliberately introduced Speciesa) After habitat loss, invasive species is the next biggest problemb) Species may benefit us, but harm others (98% of food is from introduced organisms)c) Without natural predators, they can take over and replace native speciesd) Figure 19-14 shows some harmful species

Page 199

Fig. 9-11, p. 200


e) The us kills over 14 million cats & dogs a year due to overpopulation

Case Study: The Kudzu Vine Page 199

Imported from Japan in the 1930s

“ The vine that ate the South”

Could there be benefits of kudzu?


5) Some accidentally introduced species cause problemsa) Many come in as stowaways with cargob) Some in ballast water of shipsc) Examples

Fire ant (killed 90% of native)Burmese python- released pet

6) Prevention Is the Best Way to Reduce Threats

a) Fund research programsb) Increase ground surveys &

satellite observation to detect invasions

c) Set up inspection of imported goods

d) Set treaties to ban harmful invader species trading

e) Have ships dump ballast water at sea

f) Find natural control methods

Fig. 9-14, p. 203

Case Study: Where Have All the Honeybees Gone?

Honeybees responsible for 80% of insect-pollinated plants

Dying due to?• Pesticides• Parasites•Bee colony collapse syndrome

Case Study: Polar Bears and Global Warming

Environmental impact on polar bears• Less summer sea ice

• PCBs and DDT

2007: Threatened species list

7) Illegal Killing, Capturing, and Selling of Wild Species Threatens Biodiversity

a) Illegally killed for parts or sold to collectors(about $10 billion a year)

b) 2/3 of the animals die in transit c) The internet has increased the

trade of illegal animalsd) Research and Education is a key to

stopping this tradee) Trade for pets is also profitable,

about 50 die for every one sold

f) Many imported animals carry infectious disease

g) About 25 million homes have exotic pets

h) Also exotic plants are endangered because of this type of trade

i) As these become endangered, their price goes up on the black market

j) Species also have value by surviving in the wild

k) Some former poachers make money through ecotourism

Individuals Matter: Jane Goodall

Primatologist and anthropologist

45 years understanding and protecting chimpanzees• Chimps have tool-making skills

8) Rising Demand for Bush Meat Threatens Some African Species

a) Hunting wildlife for foodb) Increased population has endangered

many speciesc) Also sold to restaurants as exotic

foodsd) Overfishing has also caused an

increase in the need for bush meate) This has lead to local extinctions

and some complete extinction (red colobus monkey)

f) Also threatens carnivores g) Also spreads diseases (AIDS & Ebola)

9-4 How Can We Protect Wild Species from Premature Extinction?

1) International Treaties

a) CITES (Convention on International Trade in Endangered Species):

1. 172 countries, bans hunting, capturing & selling threatened or endangered species

2. Enforcement varies, small fines, self exemption, not all countries have signed it

b) CBD (Convention on Biological Diversity

1. 190 countries (not US)

2. Reversing decline & shares benefits of genetic resources

Case Study: The U.S. Endangered Species Act page 207

Endangered Species Act (ESA): 1973 and later amended in 1982, 1983, and 1985

Identify and protect endangered species in the U.S. and abroad

Hot Spots Habitat Conservation Plan (HCP) colony Mixed reviews of the ESA

• Weaken it Repeal it Modify it

• Strengthen it Simplify it Streamline it

Science Focus: Accomplishments of the Endangered Species Act

Species listed only when serious danger of extinction Takes decades for most species to become

endangered or extinct More than half of the species listed are stable or

improving Budget has been small Suggested changes to ESA

• Increase the budget

• Develop recovery plans more quickly

• Establish a core of the endangered organism’s survival habitat

9-4 How Can We Protect Wild Species from Premature Extinction? (2)

3) Wildlife refuges and protected areas

a) 1903, T. Roosevelt established the US federal wildlife refuge at Pelican Island, Fa

b) Now 547 refuges

c) ¾ are wetland sanctuaries

d) 1/5 of US endangered and threatened species have habitats in the system

4) Gene Banks, botanical gardens, wildlife farms

a) Gene (seed) banks: store genetic information by refrigerating seeds

b) There are 16000 botanical gardens and arboreta containing about 1/3 of the world’s know plants

(only 3% of rare and threatened plants)

c) Farms raise animals for sale, food etc, reducing risk of wild species

5) Zoos & aquariums

a) Egg Pulling: collects wild eggs, hatch them in zoo

b) Captive breeding: breed animals in the zoo

c) Also artificial insemination, embryo transfer, incubators and cross-fostering

d) Most reintroductions fail because of lack of habitat, individual can’t survive in wild, overhunting & poaching

e) Captive population must be between 100-500 to prevent extinction

f) Aquariums are good for education, but are not good gene banks, due to size and cost

g) Precautionary principle: we need to take precautions when there is potentially harmful events, even if some cause & effect relationships have not been established. (page 211)

Case Study: Trying to Save the California Condor (page 210)

Largest North American bird

Nearly extinct• Birds captured and breed in captivity

By 2007, 135 released into the wild• Threatened by lead poisoning

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Sustaining Biodiversity: The Species Approach