Species diversity Species Diversity = the number or variety of species in the world or in a particular region 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

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 inferior offspring

Ecosystem diversity Ecosystem diversity = the number and variety of ecosystems Also encompasses differing communities and habitats Rapid vegetation change and varying landscapes within an ecosystem promote higher levels of biodiversity

Measuring biodiversity is not easy Out of the estimated 3 - 100 million species on Earth, only 1.7 - 2 million species have been successfully catalogued Very difficult to identify species Many remote spots on Earth remain unexplored Small organisms are easily overlooked Many species look identical until thoroughly examined Entomologist Terry Erwin found 163 beetle species specialized on one tree species

Biodiversity is unevenly distributed Living things are distributed unevenly across Earth Latitudinal gradient = species richness increases towards the equator Canada has 30 - 100 species of breeding birds, while Costa Rica has more than 600 species

Latitudinal gradient has many causes Climate stability, high plant productivity, and no glaciation Tropical biomes support more species and show more species evenness Diverse habitats increase species diversity Human disturbance can increase habitat diversity But only at the local level

Biodiversity provides 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 = $16 - 54 trillion per year

Biodiversity helps 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 If the species can be functionally replaced by others, it may make little difference Extinction of a keystone species may cause other species to decline or disappear “To keep every cog and wheel is the first precaution of intelligent tinkering” (Aldo Leopold)

Biodiversity enhances food security Genetic diversity within crops is enormously valuable Turkey’s wheat crops received $50 billion worth of disease resistance from wild wheat Wild strains provide disease resistance and have the ability to grow back year after year without being replanted New potential food crops are waiting to be used Serendipity berry produces a sweetener 3,000 times sweeter than sugar

Some potential new food sources

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

Biodiversity generates economic benefits People like to experience protected natural areas, creating economic opportunities for residents, particularly in developing countries 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 on native species But, too many visitors to natural areas can degrade the outdoor experience and disturb wildlife

People value and seek out 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

Do we have ethical obligations to other species? Humans are part of nature and need resources to survive But, we also have conscious reasoning ability and can control our actions Our ethics have developed from our intelligence and our ability to make choices Many people feel that other organisms have intrinsic value and an inherent right to exist

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

Extinction is a natural process Paleontologists estimate 99% of all species that ever lived are now extinct Background rate of extinction = natural extinctions for a variety of reasons 1 extinction per 1 to 10 million species for mammals and marine species 1 species out of 1,000 mammal and marine species would go extinct every 1,000 to 10,000 years

What makes a species vulnerable to extinction? Specialized niche Low reproductive rate Blue whales, giant panda, rhinoceros Feeds at high trophic level Bengal tiger, bald eagle Fixed migratory patterns Blue whale, whooping crane, sea turtles Commercially valuable Snow leopard, tigers, elephants, rare birds, orchids Rare/Narrow Distribution (island species) Need Large Territory Condor, Florida panther

Earth has experienced five mass extinctions In the past 440 million years, mass extinctions have eliminated at least 50% of all species After every mass extinction the biodiversity returned to or exceeded its original state

The current mass extinction is human caused During this Quaternary period, we may lose more than half of all species Hundreds of human-induced species extinctions, and multitudes of others, teeter on the brink of extinction The current global extinction rate is 100 to 1,000 times greater than the background rate This rate will increase tenfold in future decades due to human population growth and resource consumption

Human Impacts on Ecosystems Fragmenting and degrading habitat (stop) e.g. Tropical forests being cut at a rate of 0.6 to 2% per year Half of remaining forests lost or degraded in 25 to 83yrs Simplifying natural ecosystems Creating monocultures Using, wasting, or destroying an increasing percentage of earth’s NPP (27% of total) Strengthening some populations of pest species and disease causing bacteria by causing genetic resistance through overuse of pesticides & antibiotics Eliminating some key predators Deliberately or accidentally introducing exotic species Over harvesting of renewable resources Interfering with normal cycling and flows of energy in ecosystems

Causes of Premature Extinction of Wild Species Fig. 12-6 p. 231

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

Poaching often = Extinction CITIES Treaty

Endangered vs. Threatened So few left that species could soon become extinct over all or most of its range Threatened: Still relatively abundant but b/c of declining numbers is likely to become endangered in the near future WWF study: 30k Under threat of extinction 34% of world’s fish 25% of world’s amphibians 24% of world’s mammals 20% of world’s reptiles 14% of world’s plant species 12% of world’s bird species

Current extinction rates are higher than normal The Red List = an updated list of species facing high risks of extinctions 23% of mammal species 12% of bird species 31 - 86% of all other species Since 1970, 58 fish species, 9 bird species, and 1 mammal species has 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

Biodiversity loss is more than extinction Decreasing numbers are accompanied by smaller species’ 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%

Biodiversity loss has many causes Reasons for biodiversity losses are multifaceted, complex, and hard to determine Factors may interact synergistically Four primary causes of population decline are: Habitat alteration Invasive species Pollution Overharvesting Global climate change now is the fifth cause

Threats from Nonnative Species Fig. 12-12 p. 238

Invasive species cause biodiversity loss Introduction of non-native species to new environments Accidental: zebra mussels Deliberate: food crops Island species are especially vulnerable Invaders have no natural predators, competitors, or parasites Cost billions of dollars in economic damage

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 The damage to wildlife and ecosystems caused by pollution can be severe But it tends to be less than the damage caused by habitat alteration or invasive species

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 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

Climate change causes biodiversity loss Emissions of greenhouse gases warms 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

Warming has been the greatest in the Arctic The polar bear is being considered for the endangered species list

Biodiversity loss has a variety of causes

Conservation biology responds to biodiversity loss Conservation biology = devoted to understanding the factors that influence the loss, protection, and restoration of biodiversity Arose as scientists became alarmed at the degradation of natural systems An applied and goal-oriented science

Conservation scientists work at multiple levels Conservation biologists integrate evolution and extinction with ecology and environmental systems Design, test, and implement ways to mitigate 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 Metapopulations = a network of subpopulations Small populations are most vulnerable to extinction and need special attention

Preserving Biodiversity The Species Approach The Ecosystem Approach Goal Protect species from premature extinction Strategies Identify endangered species Protect their critical habitats Tactics Legally protect endangered species Manage habitat Propagate endangered species in captivity Reintroduce species into suitable habitats Protect populations of species in their natural habitats Strategy Preserve sufficient areas of habitats in different biomes and aquatic systems Protect habitat areas through private purchase or government action Eliminate or reduce populations of alien species from protected areas Manage protected areas to sustain native species Restore degraded ecosystems Fig. 7-2, pg. 136 PRESERVE “HOT SPOTS”

Protecting Wild Species: The Sanctuary Approach Wildlife refuges and protected areas Gene banks, botanical gardens, and farms Zoos and Aquariums

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 habitat is so fragmented, a species cannot survive 39

Protecting biodiversity Cloning – a technique to create more individuals and save species from extinction 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

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 animals 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 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 2007, the U.S. had 1,312 species listed as endangered or threatened

US Endangered Species Act (1973—Nixon!) Provides a program for the conservation of threatened and endangered plants and animals and the habitats in which they are found Dept of Interior maintains the list of 632 endangered species (over 50% plants) and 190 threatened species Anyone can petition the US F&WS to add a species to the list (if it is in danger of extinction in all or most of its range) Can be listed b/c of habitat destruction, overexploitation, disease/predation, inadequacy of existing regulations, any human threat to its continued existence Law prohibits any action (either administrative or “real”) that results in the “taking” of a listed species OR ADVERSELY AFFECTS HABITAT Illegal to take, possess, sell, transport listed sp. Recovery Plan is written for each species Provides for acquire land that preserves these species

The ESA is controversial Many Americans support protection of 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 44

Despite opposition, the ESA has had successes Peregrine falcons, brown pelicans, bald eagles, and others have recovered and are no longer listed 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 In recent years, political forces have attempted to weaken the ESA

The Lacey Act Overview. This Act authorizes the Secretary of the Interior to adopt measures to aid in restoring game and other birds in parts of the U.S. where they have become scarce or extinct and to regulate the introduction of birds and animals in areas where they had not existed. All sections but one of the original 1900 Act have been repealed and either restated in or reenacted by other code provisions. This is a summary of the one remaining section of the original Lacey Act. Game and Wild Bird Preservation. The purposes of the Act are to aid in the restoration of game and other wild birds in parts of the U.S. where they have become scarce or extinct and to regulate the introduction of American or foreign birds or animals in localities where they have not previously existed. The duties and powers of the Department of the Interior include the preservation, distribution, introduction and restoration of game and other wild birds.

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

International conservation efforts UN Convention on International Trade in Endangered Species of Wild Fauna and Flora (1973) (CITES) – 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 2007, 188 nations had signed on Iraq, Somalia, the Vatican, and the U.S. did not join 48

Habitat alteration causes biodiversity loss The greatest cause of biodiversity loss Farming simplifies communities Grazing modifies the grassland structure and species composition Clearing forests removes resources organisms need Hydroelectric dams turn rivers into reservoirs upstream Urbanization and suburban sprawl reduce natural communities A few species (i.e., pigeons, rats) benefit from changing habitats

Habitat alteration has occurred in every biome Particularly in tropical rainforests, savannas, and tropical dry forests

Island biogeography 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

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

Island Biogeography

Small “islands” of forest rapidly lose species Forests are fragmented by roads and logging Small forest fragments lose diversity fastest Starting with large species Fragmentation is one of the prime threats to biodiversity

The species-area curve Large islands contain more species than small islands They are easier to find and have lower extinction rates They possess more habitats

Biodiversity hotspots Biodiversity hotspots – prioritizes regions most important globally for biodiversity Support a great number of 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 56

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

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 Protecting land deprives people access to resources But, it can guarantee that these resources will not be used up or sold to foreign corporations and can instead be sustainably managed Many projects have succeeded But, others have not, due mainly to funding problems 58

Innovative economic strategies Debt-for-nature swap = a conservation organization pays off a portion of a developing country’s international debt In exchange for a promise by the country to set aside reserves Fund environmental education, and Better manage protected areas Conservation concession = conservation organizations pay nations to conserve, and not sell, resources 59

Conclusion Loss of biodiversity will result in a mass extinction 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 60