1. Chapter 8 Biodiversity and Conservation Biology

2. This lecture will help you understand:
The scope of Earth’s biodiversity
Background rates and mass extinction
Primary causes of biodiversity loss
The benefits of biodiversity
Conservation biology
Biodiversity conservation efforts

3. Central Case: Saving the Siberian tiger
Although tigers once roamed across Asia, today they are exceedingly rare and approaching extinction.
Siberian tigers are the largest cat in the world.
The Russian Far East mountains house the last remaining Siberian tigers.
Historically, native people rarely killed tigers.
Recently, the wild population approached extinction.
Hunting, poaching, and habitat destruction from road building, logging, and agriculture
International conservation groups are working to save the species from extinction.
Research, education, zoos, and captive breeding programs

4. Biodiversity encompasses several levels
Humans are diminishing Earth’s diversity of life.
Biodiversity: sum total of all organisms in an area
Split into three specific levels:
Species diversity
Genetic diversity
Ecosystem diversity

5. Species diversity
Species diversity: the number or variety of species in the world or in a particular region
Species richness: the number of species
Evenness or relative abundance: extent to which numbers of individuals of different species are equal or skewed
Speciation generates new species and adds to species richness.
Extinction reduces species richness.

6. The taxonomy of species
Taxonomists: scientists who classify species
Common ancestry, ability to interbreed
Genera: related species are grouped together
Families: groups of genera
Every species has a two-part scientific name: genus and species.

7. Subspecies: the level below a species
Subspecies: populations of species that occur in different areas and differ slightly from each other
Divergence stops short of separating the species.
Subspecies are denoted with a third part of the scientific name.
Siberian tiger = Panthera tigris altaica
Bengal tiger = Panthera tigris tigris
All subspecies of tigers have disappeared from 93% of their historic range.

8. Genetic diversity
Encompasses the differences in DNA among individuals within species and populations
The raw material for adaptation to local conditions
Populations with higher genetic diversity can survive.
They can cope with environmental change.
Populations with low genetic diversity are vulnerable.
To environmental change
Disease
Inbreeding depression: genetically similar parents mate and produce defective offspring

9. Ecosystem diversity
Ecosystem diversity: the number and variety of ecosystems
It also encompasses differing communities and habitats.
Sizes, shapes, and interconnectedness of patches within habitats, communities, or ecosystems

10. Some groups contain more species than others
Species are not evenly distributed among taxonomic groups.
Insects predominate over all other life-forms.
40% of all insects are beetles.
Groups accumulate species by:
Adaptive radiation
Allopatric speciation
Low rates of extinction

11. Measuring biodiversity is not easy
Species richness is a good gauge for overall biodiversity.
Out of our “best guess” estimates of 5–30 million species on Earth, only 1.7–2 million species have been identified and described.
Very difficult to identify species
Small organisms are easily overlooked.
Many species look identical until closely examined.
Many remote spots on Earth remain unexplored.

12. Biodiversity is unevenly distributed
Living things are distributed unevenly across Earth.
Latitudinal gradient: species richness increases toward the equator
Equatorial regions have higher plant productivity, stable climates, and no glaciation.
Diverse habitats increase niches, which increase species diversity.
Ecotones (areas where habitats intermix) often have higher diversity.
Human disturbance can increase habitat diversity.
But only at the local level

13. Biodiversity losses and species extinction
Extinction: occurs when the last member of a species dies and the species ceases to exist
Extirpation: the disappearance of a particular population from a given area, but not the entire species globally
Can lead to extinction
Paleontologists estimate 99% of all species are now extinct.
Background rate of extinction: natural extinctions for a variety of reasons
Mammal and marine species: 1 species out of 1,000 become extinct every 1,000 to 10,000 years, which translates to:
1 extinction per 1–10 million species

14. Earth has experienced five mass extinctions
In the past 440 million years, mass extinctions have eliminated at least 50% of all species.
Dinosaurs went extinct at the end of the Cretaceous period (65 million years ago) from an asteroid impact.

15. The current mass extinction is human caused
During our modern era (Quaternary period), we may lose more than half of all species.
Today’s extinction event differs from others because it is…
Caused by humans, and
Humans will suffer because of it
The current global extinction rate is 100 to 1,000 times greater than the background rate.
This rate will increase tenfold in future decades.

16. People have hunted species to extinction for millennia
Extinctions followed human arrival on islands and continents.

17. Current extinction rates are higher than normal
The Red List: an updated list of species facing high risks of extinctions
22% of mammal species
12% of bird species
16–86% of all other species
Since 1970, 58 fish species, 9 bird species, and 1 mammal species have gone extinct.
In the U.S. in the last 500 years, 236 animal and 17 plant species are confirmed extinct.
Actual numbers are undoubtedly higher.

18. Biodiversity loss is more than extinction
Population is declining
Accompanied by shrinking geographic ranges
Genetic, ecosystem, and species diversity are being lost.
The Living Planet Index summarizes trends in populations.
Between 1970 and 2003, the Index fell by 30%.

19. Biodiversity loss has many causes
Reasons for biodiversity losses are multifaceted, complex, and hard to determine.
Four primary causes of population decline are:
Habitat alteration
Invasive species
Pollution
Overharvesting
Global climate change now is the fifth cause.
Each factor is intensified by human population growth and resource consumption.

20. Habitat alteration causes biodiversity loss
The greatest cause of biodiversity loss
Farming simplifies communities
Grazing modifies grassland structure and species composition
Clearing forests removes resources that organisms need.
Hydroelectric dams turn rivers into upstream reservoirs and affect floodplains downstream.
Urbanization and suburban sprawl reduce natural communities.
A few species (i.e., pigeons, rats) benefit from changing habitats.
Less than 1% of North America’s Great Plains remains, and grassland bird populations have declined 82–99%.

21. Habitat alteration occurs in every biome
Particularly in tropical rainforests, tropical dry forests, and savannas

22. Invasive species cause biodiversity loss
Introduction of non-native species to new environments
Accidental: zebra mussels
Intentional: food crops
Island species haven’t evolved defenses and are very vulnerable.
Invaders have no natural predators, competitors, or parasites.
Cost billions of dollars in economic damage each year

23. Examples of exotic species causing problems

24. Pollution causes biodiversity loss
Harms organisms in many ways
Air pollution degrades forest ecosystems.
Water pollution adversely affects fish and amphibians.
Agricultural runoff harms terrestrial and aquatic species.
The effects of oil and chemical spills on wildlife are dramatic and well known.
Although pollution is a substantial threat…
It tends to be cause less damage than habitat alteration or invasive species.

25. Overharvesting causes biodiversity loss
Vulnerable species are large, few in number, long-lived, and have few young (K-selected species).
The Siberian tiger is hunted without rules and regulations.
The early 1990s saw increased tiger poaching because of powerful economic incentives.
Many other species affected: Atlantic gray whale, sharks, gorillas
Today the oceans contain only 10% of the large animals they once did.

26. Climate change causes biodiversity loss
Our manipulation of earth’s climate system is having global impacts on biodiversity.
Emissions of greenhouse gases warm temperatures.
Modifies global weather patterns and increases the frequency of extreme weather events
Increases stress on populations and forces organisms to shift their geographic ranges
Most animals and plants will not be able to cope.

27. Warming has been the greatest in the Arctic
The polar bear has been listed on the U.S. endangered species list.

28. Biodiversity loss has causes and consequences

29. Biodiversity benefits: free ecosystem services
Provides food, shelter, fuel
Purifies air and water and detoxifies wastes
Stabilizes climate, moderates floods, droughts, wind, temperature
Generates and renews soil fertility and cycles nutrients
Pollinates plants and controls pests and disease
Maintains genetic resources
Provides cultural and aesthetic benefits
Allows us to adapt to change
The annual value of just 17 ecosystem services = $ trillion per year

30. Biodiversity benefits: maintain ecosystem function
Biodiversity increases the stability and resilience of communities and ecosystems.
Decreased biodiversity reduces a natural system’s ability to function and provide services to our society.
The loss of a species affects ecosystems differently.
Extinction of a keystone species may cause other species to decline or disappear.

31. Biodiversity benefits: enhanced food security
Genetic diversity in crops is enormously valuable.
Turkey’s wheat crops received $50 billion worth of disease resistance from wild wheat.
New potential food crops are waiting to be used.
Serendipity berry produces a sweetener 3,000 times sweeter than sugar.
Salt tolerant grasses can be irrigated with seawater.

32. Organisms provide drugs and medicines
Each year pharmaceutical products owing their origin to wild species generate up to $150 billion in sales.
The rosy periwinkle produces compounds that treat Hodgkin's disease and leukemia.

33. Biodiversity benefits: economic benefits
Biodiversity provides a source of income through tourism.
Ecotourism: people visit natural areas, creating economic opportunity for residents living near those areas
Costa Rica: rainforests
Australia: Great Barrier Reef
Belize: reefs, caves, and rainforests
A powerful incentive to preserve natural areas and reduce impacts on the landscape and species
But too many visitors to natural areas can degrade the outdoor experience and disturb wildlife

34. Biodiversity benefits: people value nature
Biophilia: connections that humans subconsciously seek with life
Our affinity for parks and wildlife
Keeping of pets
High value of real estate with views of natural lands
Nature deficit disorder: alienation from the natural environment
May be behind the emotional and physical problems of the young

35. Do we have ethical obligations to other species?
Many feel that living organisms have an innate right to exist.
Biodiversity conservation is justified on ethical grounds.
“If tigers aren’t worth saving, then what are we all about? What is worth saving?”
Despite our ethical convictions, and biodiversity’s many benefits, the future of biodiversity remains far from secure.

36. Conservation biology responds to biodiversity loss
Conservation biology: studies the factors that influence the loss, protection, and restoration of biodiversity
Scientists became alarmed at the degradation of natural systems.
Applied and goal-oriented, it tries to minimize human impacts.
Conservation geneticists: study genetic attributes of organisms to infer the status of their population
Minimum viable population: how small a population can become before it runs into problems
Conservation biologists try to learn how likely a population is to persist or go extinct, particularly small and isolated ones.

37. Island biogeography
Protecting habitat and species requires thinking and working at the landscape level.
Equilibrium theory of island biogeography: explains how species come to be distributed among oceanic islands
Also applies to “habitat islands” — patches of one habitat type isolated within a “sea” of others
Explains how the number of species on an island results from an equilibrium between immigration and extirpation
Predicts an island’s species richness based on the island’s size and distance from the mainland

38. Species richness results from island size and distance
Fewer species colonize an island far from the mainland.
Large islands have higher immigration rates.
Large islands have lower extinction rates.

39. The species-area curve
Area effect: large islands contain more species than small islands
They are easier to find, and their larger populations have lower extinction rates.
They possess more habitats.
The number of species on an island doubles as the island size increases tenfold.

40. Small “islands” of habitat rapidly lose species
Forests are fragmented by roads and logging.
Small forest fragments lose diversity fastest.
Starting with large species

41. Should conservation focus on endangered species?
Endangered Species Act (1973) (ESA): forbids the government and private citizens from taking actions that destroy endangered species or their habitats
To prevent extinction
Stabilize declining populations
Enable populations to recover
As of 2008, the U.S. had 1,046 species listed as endangered and 307 listed as “threatened.”

42. Despite opposition, the ESA has had successes
Peregrine falcons, brown pelicans, bald eagles, and others have recovered and are no longer listed as endangered.
Intensive management has stabilized other species.
The red-cockaded woodpecker
40% of declining populations are now stable.
These successes occur despite underfunding of the U.S. Fish and Wildlife Service and the National Marine Fisheries Service.
Recently, political forces have attempted to weaken the ESA.
In 2006, 5,700 U.S. scientists wrote letters of protest to Congress.

43. The ESA is controversial
Most Americans support protecting endangered species.
Opponents feel that the ESA values endangered organisms more than the livelihood of people.
Private land use will be restricted if an endangered species is present.
“Shoot, shovel, and shut up”: landowners conceal the presence of endangered species on their land
But the ESA has stopped few development projects.
Habitat conservation plans and safe harbor agreements: landowners can harm species if they improve habitat for the species in other places 43

44. Other countries have their own version of the ESA
Species at Risk Act (2002): Canada’s endangered species law
Stresses cooperation between landowners and provincial governments
Criticized as being too weak
Other nations’ laws are not enforced.
The Wildlife Conservation Society has to help pay for Russians to enforce their own anti-poaching laws.

45. Protecting biodiversity
Captive breeding: individuals are bred and raised with the intent of reintroducing them into the wild
Zoos and botanical gardens
Some reintroductions are controversial.
Ranchers opposed the reintroduction of wolves to Yellowstone National Park.
Some habitats are so fragmented, a species cannot survive. 45

46. Protecting biodiversity
Cloning: a technique to create more individuals and save species from extinction
DNA from an endangered species is inserted into an egg, which is implanted into a surrogate mother.
Most biologists agree that these efforts are not adequate to recreate the lost biodiversity.
Ample habitat and protection in the wild are needed to save species.

47. Umbrella species
Conservation biologists use particular species as tools to conserve communities and ecosystems.
Protecting the habitat of these umbrella species helps protect less-charismatic species that would not have generated public interest.
Flagship species: large and charismatic species used as spearheads for biodiversity conservation
The World Wildlife Fund’s panda bear
Some organizations are moving beyond the single species approach to focus on whole landscapes. 47

48. International conservation efforts
UN Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (1973): protects endangered species by banning international transport of their body parts
Convention on Biological Diversity (1992):
Seeks to conserve biodiversity
Use biodiversity in a sustainable manner
Ensure the fair distribution of biodiversity’s benefits
By 2008, 188 nations had signed on.
Iraq, Somalia, the Vatican, and the U.S. did not join. 48

49. Biodiversity hotspots
Biodiversity hotspots: an area that supports a high number of species
Endemic species: species found nowhere else in the world
The area must have at least 1,500 endemic plant species (0.5% of the world total).
It must have lost 70% of its habitat due to human impact. 49

50. There are 34 global biodiversity hotspots
2.3% of the planet’s land surface contains 50% of the world’s plant species and 42% of all terrestrial vertebrate species.

51. Community-based conservation
Protecting habitats makes good sense, but this affects people living in and near these areas.
Community-based conservation: conservation biologists actively engage local people in protecting land and wildlife
Projects provide education, retraining, and paid salaries to protect animals from poachers.
Protecting land protects resources from being used up or sold to foreign corporations. 51

52. Conclusion
Loss of biodiversity threatens to result in a mass extinction event equivalent to mass extinctions of the past.
Primary causes of biodiversity loss are:
Habitat alteration, invasive species, pollution, overharvesting of biotic resources, and climate change
Human society cannot function without biodiversity’s benefits.
Science can help save species, preserve habitats, restore populations, and keep natural ecosystems intact. 52

53. QUESTION: Review
Which level is NOT included in the concept of biodiversity?
Species
Genetics
Ecosystems
All of the above are included in this concept.
Answer: d

54. QUESTION: Review
What happens when a species experiences “inbreeding depression”?
The species becomes too large for the resource base
Genetically similar parents mate and produce inferior offspring
Genetically similar parents mate and produce superior offspring
The number and variety of species increases
An ecosystem’s biodiversity increases
Answer: b

55. QUESTION: Review Species richness increases toward the equator
According to the concept of “latitudinal gradient,” which of the following happens?
Species richness increases toward the equator
Species richness decreases toward the equator
Species richness decreases over time
Countries like Canada have many more species than expected
People in warmer climates protect species better than people in colder climates
Answer: a

56. QUESTION: Review Very small species are often overlooked.
Which of the following statements is FALSE?
Very small species are often overlooked.
Remote areas may have unidentified species.
We have identified almost all species on Earth.
There are more insect species than any other type of species.
Ecotones often have high biodiversity.
Answer: c

57. QUESTION: Review
Which of the following is the major cause of extinction?
Invasive species
Pollution
Habitat loss
Overharvesting
These are pretty much equal in causing extinction.
Answer: c

58. QUESTION: Review Biodiversity does all of the following EXCEPT:
Provide ecosystem services
Decrease food security
Maintain ecosystem function
Provide aesthetic benefits
Provide economic benefits
Answer: b

59. QUESTION: Review
According to the theory of island biogeography, which island would have the LOWEST species richness?
A large island, close to the mainland
A large island, far from the mainland
A small island, close to the mainland
A small island, far from the mainland
None of these; islands don’t really have species
Answer: d

60. QUESTION: Review A “biodiversity hotspot” is:
An area located near the equator
An area that supports few, but large, species
An area that contains naturally high numbers of people
An area that contains a large number of endemic species
An area where the wealthy can go on vacation
Answer: d

61. QUESTION: Review
Which statement about the U.S. Endangered Species Act is FALSE?
It forbids the government, but not private citizens, from harming endangered species.
It lists endangered and threatened species.
It is designed to prevent extinction.
It is designed to enable populations to increase.
It is designed to stabilize declining populations.
Answer: a

62. QUESTION: Weighing the Issues
If a pharmaceutical company produces a medicine from a plant found in Costa Rica that will earn millions of dollars, who should reap the financial benefits?
The company, because it had to pay millions of dollars to discover and produce the drug
Costa Rica, because it had the plant that produced the drug
Taxpayers, because they fund lots of research through their tax dollars
Native people in Costa Rica, because the company would not have found the drug without their help
The native people, the company, and Costa Rica, because all played a vital part in the drug’s discovery and development
Answer: any

63. QUESTION: Weighing the Issues
Have you ever personally experienced evidence of the biophilia hypothesis?
Yes, I frequently feel a connection to other living things and nature
Yes, sometimes, on a particularly lovely day
Maybe, but I’m not sure
No, because I don’t get to experience nature often enough
Definitely not, unless I was going to earn money from using nature
Answer: any

64. QUESTION: Interpreting Graphs and Data
Where would ecotourists go to view the maximum species richness on these islands?
a) Redonda b) Montserrat c) Puerto Rico
Hispaniola e) Jamaica
Answer: d

65. QUESTION: Interpreting Graphs and Data
Which biome lost the most area by 1950? Which biome lost the most area in recent decades?
Temperate grassland, tropical dry forest
Desert, savanna
Chaparral, tundra
Temperate grassland, desert
Answer: a