47 lecture ppt

Biology

Sylvia S. Mader Michael Windelspecht

Chapter 47

Conservation of

Biodiversity

Lecture Outline

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Outline

• 47.1 Conservation Biology and Biodiversity

• 47.2 Value of Biodiversity

• 47.3 Causes of Extinction

47.1 Conservation Biology and

Biodiversity

• Considers all aspects of biodiversity

– General goal is conserving natural resources

for this and future generations

– Primary goal is the management of

biodiversity

• The variety of life on Earth

Conservation Biology and

Biodiversity

• For conservation biology to be effective,

scientists must evaluate larger connections

within the biosphere

– High level of biodiversity is desirable

– Causes of present-day extinction, how to prevent

future extinctions from occurring, and consequences of reduced biodiversity

– Bioinformatics is utilized to protect biodiversity

• Collecting of, analyzing, and making readily available

Conservation Biology and

Biodiversity

• Biodiversity

– At its simplest level, biodiversity refers to the

variety of species on Earth

• Estimated that between 10 and 50 million species currently exist

• Endangered Species

– One that is in peril of immediate extinction throughout all or most of its range

• Threatened Species

– Organisms that are likely to become endangered in the near future

Conservation Biology and

Biodiversity

• Biodiversity

– Ecologists describe biodiversity as a

combination of three levels of biological

organization:

• Genetic diversity

Conservation Biology and

Biodiversity

• Biodiversity

–

Genetic diversity

refers to variations among

the members of a population

• Populations with high genetic diversity are more likely to have some individuals that can survive a change in the structure of their ecosystem

• If a species’ population is small and isolated, it is more likely to become extinct due to a limited

genetic diversity.

Conservation Biology and

Biodiversity

• Biodiversity

–

Ecosystem diversity

is dependent on

interactions of species in a particular area

• A diverse community composition will increase the levels of biodiversity in the biosphere

• An effective approach to conservation is to

conserve species that play a key role within the ecosystem

Conservation Biology and

Biodiversity

• Biodiversity

–

Landscape diversity

involves a group of

interacting ecosystems within one landscape

• Landscape – Ex: mountains, rivers, grasslands

• Fragmentation of the landscape reduces reproductive capacity and food availability

Number of Described Species

insects 900,000

plants 240,000

animals 280,000

fungi 63,665

protists 55,000 bacteria and archaea 5,000

Eagles and Bears Feed

on Spawning Salmon

11

150

100

50

0

1979 1981 1983 1985 1987 1989

bald eagle zooplankton kokanee salmon grizzly bear N u m b e r

bald eagles ( ´7)

opossum shrimp (Mysis relicta) Year kokanee salmon ( ´1 ,000)

opossum shrimp (per m2₎

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Conservation Biology and

Biodiversity

• Distribution of Biodiversity

– Biodiversity is not evenly distributed

throughout the biosphere

– Biodiversity is highest at the tropics

–

Biodiversity hotspots

• Contain about 44% of known higher plant species and 35% of terrestrial vertebrate species

47.2 Value of Biodiversity

• Direct Value

– A great number of species perform services

from which humans can derive an economic

value.

• These include:

– Medicinal value – Agricultural value

– Consumptive Use Value

Value of Biodiversity

• Direct Value (continued)

– Medicinal Value

• Most of the prescription drugs currently used in the United States were originally derived from living organisms

– Worth about $200 billion

• Ex: Rosy Periwinkle

– Chemicals from this plant are currently used to treat leukemia and Hodgkin disease

– These drugs have significantly increased survival rates for children

• Other examples include the use of penicillin in the

Value of Biodiversity

• Direct Value (continued)

– Agricultural Value

• Wheat, corn, and rice are derived from wild plants that were modified to increase their yield

• Natural predators of plant pests have been

introduced to agricultural systems to reduce the impact of the pest on plant yields

Value of Biodiversity

• Direct Value (continued)

– Consumptive Use Value

• Humans have had success cultivating crops, domesticating animals, growing trees in

plantations, etc.

– However, most freshwater and marine harvests must be hunted, rather than grown via aquaculture, for human consumption

• Additional products associated with the environment are sold commercially

– Wild fruits, vegetables, skins, fibers, beeswax and seaweed

Direct Value of Wildlife

17

Wild species, like many marine species, provide us with food.

Wild species, like the nine-banded armadillo, Dasypus novemcinctus, play a role in medical research.

Wild species, like the rosy periwinkle,

Catharanthus roseus, are sources of many medicines.

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Wild species, like rubber trees, Hevea, can provide a product indefinitely if the forest is not destroyed. Wild species, like the lesser long-nosed bat, Leptonycteris curasoae,

are pollinators of agricultural and other plants.

Wild species, like ladybugs, Coccinella, play a role in biological control of agricultural pests.

(periwinkle): © Steven P. Lynch; (armadillo): © Photodisc/Getty RF; (boat): © Getty RF (bat): © Merlin D. Tuttle/Bat Conservation International; (ladybug): © Masterfi le RF; (rubber harvest): © Bryn

Value of Biodiversity

• Indirect Value

– Based on the services ecosystems provide

simply by their own existence.

– These include:

• Biogeochemical cycles • Waste recycling

• Provision of Fresh Water • Prevention of Soil Erosion • Regulation of Climate

Value of Biodiversity

• Indirect Value (continued)

– Biogeochemical Cycles

• The biodiversity within ecosystems contributes to the workings of the water, carbon, nitrogen,

phosphorous, and other biogeochemical cycles • Humans are dependent upon these cycles for

fresh water, removal of carbon dioxide from the atmosphere, uptake of excess soil nitrogen, and provision of phosphate

Value of Biodiversity

• Indirect Value (continued)

– Waste Recycling

• Decomposers break down dead organic matter and other types of wastes into inorganic nutrients used by producers within ecosystems.

• This function aids humans

– The human population dumps millions of tons of waste material into natural ecosystems each year

Value of Biodiversity

• Indirect Value (continued)

– Provision of Fresh Water

• The water cycle provides fresh water to terrestrial ecosystems

• Humans use this fresh water in innumerable ways • Freshwater ecosystems provide us with a large

diversity of species we can use as a source of food • Forests and some other natural ecosystems soak

up water and release it at a regular rate, thereby reducing flooding

Value of Biodiversity

• Indirect Value (continued)

– Prevention of Soil Erosion

• Intact ecosystems naturally retain soil and prevent soil erosion

• The importance of this attribute is particularly observed after deforestation

Value of Biodiversity

• Indirect Value (continued)

– Regulation of Climate

• Trees provide shade and reduce the need for fans and air conditioners in the summer

• Globally, forests restore the climate by

incorporating carbon dioxide from the atmosphere • Reduction of forests reduces the carbon dioxide

uptake and oxygen output through photosynthesis

Value of Biodiversity

• Indirect Value (continued)

– Ecotourism

• In the United States, nearly $4 billion is spent on fees, travel, lodging, and food within natural

settings

Indirect Value of Ecosystems

Value of Biodiversity

• Biodiversity and Natural Ecosystems

– Large-scale changes in biodiversity have

significant impacts on ecosystems:

• Ecosystem performance improves with increasing biodiversity

1 2 4 8 Rate of Photo sy nth esi s

Number of Plant Species

16 1.0 3.0 2.5 2.0 1.5

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27

47.3 Causes of Extinction

• Known causes of species extinction are

due to:

– Habitat loss (85%)

– Exotic species (50%)

– Pollution (24%)

Causes of Extinction

• Habitat Loss

– Occurs in all ecosystems

– Recent concern focuses on tropical rain

forests and coral reefs because they are rich

in species

– Loss of habitat affects terrestrial, freshwater,

and marine biodiversity

Habitat Loss

0

Roads cut through forest

Forest occurs in patches

b. Macaws

a. Threats to wildlife

% Species Affected by Threat Disease

Overexploitation Pollution Exotic Species Habitat Loss

20 40 60 80 100

Causes of Extinction

•

Exotic Species

– Nonnative species that migrate, or are

introduced, into a new ecosystem

– Humans introduce exotic species into

ecosystems through:

• Colonization

• Horticulture and Agriculture • Accidental Transport

Exotic Species

a. b.

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Causes of Extinction

• Impact of Exotics on Islands

– Islands are particularly susceptible to

environmental discord due to the introduction

of exotic species

• Island inhabitants have native species closely adapted to one another and do not compete well with exotic species

– Ex:

» Myrtle tree introduced to the Hawaiian Islands » Brown tree snake introduced to Pacific islands

Causes of Extinction

•

Pollution

– Any environmental change that adversely

affects living things

– Third main cause of extinction

– Biodiversity is particularly threatened by

• Acid deposition • Eutrophication • Ozone depletion

Causes of Extinction

• Pollution (continued)

– Acid Deposition

• Sulfur dioxides and nitrogen oxides in automobile gas react with water in the atmosphere to form

acids that are returned to Earth as either wet or dry deposition

– Weakens trees and increases their susceptibility to disease

– Kills small decomposers and invertebrates, thereby disrupting entire ecosystems

Causes of Extinction

• Pollution (continued)

– Eutrophication

• Excess nutrient runoff from terrestrial

environments result in algal growth in lakes

• As these algae die, the decomposers in the lake break them down and reduce the amount of

oxygen in the lake.

Causes of Extinction

• Pollution (continued)

– Ozone Depletion

• Ozone (O₃) protects the surface of the Earth from harmful UV rays

– Chlorofluorocarbons released from products such freon used in older refrigerators destroy ozone

» Leads to impaired crop and tree growth, death of plankton, and impairment of immune system function

Causes of Extinction

• Pollution (continued)

– Organic Chemicals

• Organic chemicals such as nonylphenols used in a variety of human products mimic the effect of

hormones

Causes of Extinction

• Climate Change

– Refers to recent changes in the Earth’s

climate

– Increased temperature of the Earth results in

drastic climatic changes

• Temperature increase is caused, in part, by

increased concentrations of greenhouse gases, such as CO₂ that serve to trap heat within the atmosphere

– Results in ecosystem disruption and extinction

Climate Change

most probable temperature increase for 2 × CO2

maximum likely increase

minimum likely increase 0.5 1.5 2.5 3.5 4.5 5.5

Causes of Extinction

•

Overexploitation

– The number of individuals taken from the population is so great that the population becomes severely

reduced in numbers

– Positive feedback cycle

• The smaller the population, the more valuable its members, and the greater the incentive to capture the few remaining organisms

– The market forces driving overexploitation:

• Exotic Pets • Poaching • Overfishing

Trawling

a. Fishing by use of a drag net

Overexploitation of Asian Turtles

• Collection and trade of terrestrial and freshwater turtles for human consumption has surged in Asia

– 40% - 60% of all species are currently endangered

• Due to their life history characteristics (slow growth, low reproductive rates), wild populations are not likely to recover after they have been plundered.

• Major Challenges Today and in the Future include:

– Lack of knowledge of range, natural history, and conservation needs of turtle species

– Need for legislation of diverse countries to be passed that ensures the long-term survival of turtle populations

– Threat of invasive species and spread of disease from aquaculture

47.4 Conservation Techniques

• Habitat preservation and restoration are

important in preserving biodiversity

– Habitat Preservation

• Biodiversity hotspots, small areas with large numbers of endemic species not found anyplace else, are important targets for conservation

• Keystone Species

– Species that influence the viability of a community

– Extinction of these species can lead to additional extinctions and loss of biodiversity

• Flagstone Species

Conservation Techniques

• Habitat Preservation (continued)

–

Metapopulation

• Small population isolated because of habitat fragmentation

– Source Population

» One that most likely lives in a favorable area and its birth rate is most likely higher than its death rate

– Sink Population

» Organisms that have moved from a source

population to an environment not as favorable and where the birth and death rates are approximately equal

Habitat Preservation

a. Grizzly bear, Ursus arctos horribilis

b. Old-growth forest; northern spotted owl, Strix occidentalis caurina (inset)

Conservation Techniques

• Landscape Preservation

– Landscape protection for one species benefits

other wildlife in the same space

• The

Edge Effect

– The edge around a patch of habitat has

conditions different from the patch interior

– An edge reduces the amount of habitat typical

for an ecosystem

• Can result in a significant reduction in population size

Edge Effect

to edge effect

increasing percentage of patch influenced by edge effects

brown-headed cowbird chick yellow warbler chick

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Conservation Techniques

• Habitat Restoration

– Restoration ecology seeks scientific ways to

return ecosystems to their state prior

• Three Principles of restoration ecology:

– Begin as soon as possible before remaining fragments are lost

– Once natural history is understood, use biological techniques to mimic natural processes

– Goal is sustainable development