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Ch. 16 What is biodiversity? Species richness (# of species) and genetic diversity within populations Case study: the bald eagle • Factors affecting near extinction: – Habitat destruction (forests) – Hunted – Slow reproductive rate – DDT thin eggs cracked prematurely – Other pollutants: lead and mercury • Solution: – DDT banned in US (1972) – Bred in captivity and then released Why does biodiversity matter? • • • • • • ecosystem services: pollination depends on insects, bacteria decompose, presence of one organism keeps the # of others in check Greater variety of genes in crops allows for “crossing” to become more pest resistant Genetic engineering relies on existing genes – Ex: insulin, cows making more milk, pest resistant Medicines: Ex AZT (AIDS) from sponges Supply other products: wool, paper, cork, fragrances Aesthetic/ethical – beauty, all organism have value What’s causing its loss? • • • • Habitat destruction!!!!! (includes fragmentation): build roads and buildings, clear forests to grow crops, drain marshes to build, divert water for irrigation, flood habitats with dams. Linked to increasing human population – need for food and space. Ex: elephants/Africa Invasive species – compete for food, no natural predators, prey on other species ex: Kudzu, brown tree snake eating birds in Guam Pollution – acid rain destroys plants/change water pH, ozone depletion increases solar radiation, climate warming. Hurt organisms with narrow environmental requirements. (condor – require lg. territories - poisoned by lead in bullets in carrion) Overexploitation – killed for fun, b/c a nuisance, or profit, commercial harvest (live organisms) Ex: elephants •CURRENTLY IN 6TH MASS EXTINCTION (human caused) •MASS EXTINCTIONS IN PAST Case study: amphibians Are bellweather species (sentinel species) - #s are early warning of environmental damage Reliant on water for reproduction, early life cycle, breathing – sensitive to pollution Declining numbers and deformities Reasons: Pesticides like atrazine – endocrine disrupter thinning ozone increase UV radiation What can humans do about preserving biodiversity? • Conservation biology: in situ (in nature) and ex situ conservation (in human controlled settings) – Protecting habitats – larger the better, prioritize high diversity areas, national parks • Problems: governments unable/unwilling to enforce laws – Restoring habitats - $$ – Reintroduction of species – from elsewhere or captivity – Zoos (artificial insemination), botanical gardens, seed banks – Provide economic incentives to local people : pay for discovery of helpful plants, ecotourism, reduce debt in exchange for preserving biodiversity. Ex: Madagascar and US Endangered Species Act (1973) Gives US Fish and Wildlife Service power to protect (from hunting, collecting, harming habitat) endangered and threatened species Traits of endangered species: requiring a large territory: CA condor island living – many found nowhere else (endemic), evolved w/o predators and diseases and then vulnerable low reproductive success – green sea turtle particular beaches small population size – need enough males/females specialized feeding habits – pandas only eat bamboo Marine Mammal Protection Act Prevents hunting, killing, capturing, or harassing a marine mammal Bans the import, export, and sale of marine mammals or parts CITES (Convention on International Trade in Endangered Species) Where is it the greatest problem? Tropical rain forests Central/South America, central Africa, Southeast Asia Migratory birds Biodiversity hotspots – small areas with high number of endemic species Most are tropical; many are islands