2This lecture will help you understand: The scope of Earth’s biodiversityBackground rates and mass extinctionPrimary causes of biodiversity lossThe benefits of biodiversityConservation biologyBiodiversity conservation efforts
3Central 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 agricultureInternational conservation groups are working to save the species from extinction.Research, education, zoos, and captive breeding programs
4Biodiversity encompasses several levels Humans are diminishing Earth’s diversity of life.Biodiversity: sum total of all organisms in an areaSplit into three specific levels:Species diversityGenetic diversityEcosystem diversity
5Species diversitySpecies diversity: the number or variety of species in the world or in a particular regionSpecies richness: the number of speciesEvenness or relative abundance: extent to which numbers of individuals of different species are equal or skewedSpeciation generates new species and adds to species richness.Extinction reduces species richness.
6The taxonomy of species Taxonomists: scientists who classify speciesCommon ancestry, ability to interbreedGenera: related species are grouped togetherFamilies: groups of generaEvery species has a two-part scientific name: genus and species.
7Subspecies: the level below a species Subspecies: populations of species that occur in different areas and differ slightly from each otherDivergence stops short of separating the species.Subspecies are denoted with a third part of the scientific name.Siberian tiger = Panthera tigris altaicaBengal tiger = Panthera tigris tigrisAll subspecies of tigers have disappeared from 93% of their historic range.
8Genetic diversityEncompasses the differences in DNA among individuals within species and populationsThe raw material for adaptation to local conditionsPopulations with higher genetic diversity can survive.They can cope with environmental change.Populations with low genetic diversity are vulnerable.To environmental changeDiseaseInbreeding depression: genetically similar parents mate and produce defective offspring
9Ecosystem diversityEcosystem diversity: the number and variety of ecosystemsIt also encompasses differing communities and habitats.Sizes, shapes, and interconnectedness of patches within habitats, communities, or ecosystems
10Some 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 radiationAllopatric speciationLow rates of extinction
11Measuring 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 speciesSmall organisms are easily overlooked.Many species look identical until closely examined.Many remote spots on Earth remain unexplored.
12Biodiversity is unevenly distributed Living things are distributed unevenly across Earth.Latitudinal gradient: species richness increases toward the equatorEquatorial 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
13Biodiversity losses and species extinction Extinction: occurs when the last member of a species dies and the species ceases to existExtirpation: the disappearance of a particular population from a given area, but not the entire species globallyCan lead to extinctionPaleontologists estimate 99% of all species are now extinct.Background rate of extinction: natural extinctions for a variety of reasonsMammal 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
14Earth 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.
15The 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, andHumans will suffer because of itThe current global extinction rate is 100 to 1,000 times greater than the background rate.This rate will increase tenfold in future decades.
16People have hunted species to extinction for millennia Extinctions followed human arrival on islands and continents.
17Current extinction rates are higher than normal The Red List: an updated list of species facing high risks of extinctions22% of mammal species12% of bird species16–86% of all other speciesSince 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.
18Biodiversity loss is more than extinction Population is decliningAccompanied by shrinking geographic rangesGenetic, ecosystem, and species diversity are being lost.The Living Planet Index summarizes trends in populations.Between 1970 and 2003, the Index fell by 30%.
19Biodiversity loss has many causes Reasons for biodiversity losses are multifaceted, complex, and hard to determine.Four primary causes of population decline are:Habitat alterationInvasive speciesPollutionOverharvestingGlobal climate change now is the fifth cause.Each factor is intensified by human population growth and resource consumption.
20Habitat alteration causes biodiversity loss The greatest cause of biodiversity lossFarming simplifies communitiesGrazing modifies grassland structure and species compositionClearing 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%.
21Habitat alteration occurs in every biome Particularly in tropical rainforests, tropical dry forests, and savannas
22Invasive species cause biodiversity loss Introduction of non-native species to new environmentsAccidental: zebra musselsIntentional: food cropsIsland 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
24Pollution causes biodiversity loss Harms organisms in many waysAir 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.
25Overharvesting 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, gorillasToday the oceans contain only 10% of the large animals they once did.
26Climate 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 eventsIncreases stress on populations and forces organisms to shift their geographic rangesMost animals and plants will not be able to cope.
27Warming has been the greatest in the Arctic The polar bear has been listed on the U.S. endangered species list.
29Biodiversity benefits: free ecosystem services Provides food, shelter, fuelPurifies air and water and detoxifies wastesStabilizes climate, moderates floods, droughts, wind, temperatureGenerates and renews soil fertility and cycles nutrientsPollinates plants and controls pests and diseaseMaintains genetic resourcesProvides cultural and aesthetic benefitsAllows us to adapt to changeThe annual value of just 17 ecosystem services = $ trillion per year
30Biodiversity 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.
31Biodiversity 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.
32Organisms 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.
33Biodiversity benefits: economic benefits Biodiversity provides a source of income through tourism.Ecotourism: people visit natural areas, creating economic opportunity for residents living near those areasCosta Rica: rainforestsAustralia: Great Barrier ReefBelize: reefs, caves, and rainforestsA powerful incentive to preserve natural areas and reduce impacts on the landscape and speciesBut too many visitors to natural areas can degrade the outdoor experience and disturb wildlife
34Biodiversity benefits: people value nature Biophilia: connections that humans subconsciously seek with lifeOur affinity for parks and wildlifeKeeping of petsHigh value of real estate with views of natural landsNature deficit disorder: alienation from the natural environmentMay be behind the emotional and physical problems of the young
35Do 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.
36Conservation biology responds to biodiversity loss Conservation biology: studies the factors that influence the loss, protection, and restoration of biodiversityScientists 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 populationMinimum viable population: how small a population can become before it runs into problemsConservation biologists try to learn how likely a population is to persist or go extinct, particularly small and isolated ones.
37Island biogeographyProtecting 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 islandsAlso applies to “habitat islands” — patches of one habitat type isolated within a “sea” of othersExplains how the number of species on an island results from an equilibrium between immigration and extirpationPredicts an island’s species richness based on the island’s size and distance from the mainland
38Species 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.
39The species-area curve Area effect: large islands contain more species than small islandsThey 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.
40Small “islands” of habitat rapidly lose species Forests are fragmented by roads and logging.Small forest fragments lose diversity fastest.Starting with large species
41Should 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 habitatsTo prevent extinctionStabilize declining populationsEnable populations to recoverAs of 2008, the U.S. had 1,046 species listed as endangered and 307 listed as “threatened.”
42Despite 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 woodpecker40% 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.
43The 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 landBut 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 places43
44Other countries have their own version of the ESA Species at Risk Act (2002): Canada’s endangered species lawStresses cooperation between landowners and provincial governmentsCriticized as being too weakOther nations’ laws are not enforced.The Wildlife Conservation Society has to help pay for Russians to enforce their own anti-poaching laws.
45Protecting biodiversity Captive breeding: individuals are bred and raised with the intent of reintroducing them into the wildZoos and botanical gardensSome reintroductions are controversial.Ranchers opposed the reintroduction of wolves to Yellowstone National Park.Some habitats are so fragmented, a species cannot survive.45
46Protecting biodiversity Cloning: a technique to create more individuals and save species from extinctionDNA 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.
47Umbrella speciesConservation 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 conservationThe World Wildlife Fund’s panda bearSome organizations are moving beyond the single species approach to focus on whole landscapes.47
48International 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 partsConvention on Biological Diversity (1992):Seeks to conserve biodiversityUse biodiversity in a sustainable mannerEnsure the fair distribution of biodiversity’s benefitsBy 2008, 188 nations had signed on.Iraq, Somalia, the Vatican, and the U.S. did not join.48
49Biodiversity hotspots Biodiversity hotspots: an area that supports a high number of speciesEndemic species: species found nowhere else in the worldThe 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
50There 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.
51Community-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 wildlifeProjects 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
52ConclusionLoss 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 changeHuman society cannot function without biodiversity’s benefits.Science can help save species, preserve habitats, restore populations, and keep natural ecosystems intact.52
53QUESTION: ReviewWhich level is NOT included in the concept of biodiversity?SpeciesGeneticsEcosystemsAll of the above are included in this concept.Answer: d
54QUESTION: ReviewWhat happens when a species experiences “inbreeding depression”?The species becomes too large for the resource baseGenetically similar parents mate and produce inferior offspringGenetically similar parents mate and produce superior offspringThe number and variety of species increasesAn ecosystem’s biodiversity increasesAnswer: b
55QUESTION: Review Species richness increases toward the equator According to the concept of “latitudinal gradient,” which of the following happens?Species richness increases toward the equatorSpecies richness decreases toward the equatorSpecies richness decreases over timeCountries like Canada have many more species than expectedPeople in warmer climates protect species better than people in colder climatesAnswer: a
56QUESTION: 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
57QUESTION: ReviewWhich of the following is the major cause of extinction?Invasive speciesPollutionHabitat lossOverharvestingThese are pretty much equal in causing extinction.Answer: c
58QUESTION: Review Biodiversity does all of the following EXCEPT: Provide ecosystem servicesDecrease food securityMaintain ecosystem functionProvide aesthetic benefitsProvide economic benefitsAnswer: b
59QUESTION: ReviewAccording to the theory of island biogeography, which island would have the LOWEST species richness?A large island, close to the mainlandA large island, far from the mainlandA small island, close to the mainlandA small island, far from the mainlandNone of these; islands don’t really have speciesAnswer: d
60QUESTION: Review A “biodiversity hotspot” is: An area located near the equatorAn area that supports few, but large, speciesAn area that contains naturally high numbers of peopleAn area that contains a large number of endemic speciesAn area where the wealthy can go on vacationAnswer: d
61QUESTION: ReviewWhich 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
62QUESTION: 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 drugCosta Rica, because it had the plant that produced the drugTaxpayers, because they fund lots of research through their tax dollarsNative people in Costa Rica, because the company would not have found the drug without their helpThe native people, the company, and Costa Rica, because all played a vital part in the drug’s discovery and developmentAnswer: any
63QUESTION: Weighing the Issues Have you ever personally experienced evidence of the biophilia hypothesis?Yes, I frequently feel a connection to other living things and natureYes, sometimes, on a particularly lovely dayMaybe, but I’m not sureNo, because I don’t get to experience nature often enoughDefinitely not, unless I was going to earn money from using natureAnswer: any
64QUESTION: Interpreting Graphs and Data Where would ecotourists go to view the maximum species richness on these islands?a) Redonda b) Montserrat c) Puerto RicoHispaniola e) JamaicaAnswer: d
65QUESTION: 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 forestDesert, savannaChaparral, tundraTemperate grassland, desertAnswer: a