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Chapter 13: Biodiversity In this chapter the following topics will be covered: Biodiversity and the species concept B

Chapter 13: Biodiversity In this chapter the following topics will be covered: Biodiversity and the species concept Benefits of biodiversity Humans threaten biodiversity Biodiversity protection and Endangered Species Act Ecosystem management and captive breeding programs .

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Chapter 13: Biodiversity In this chapter the following topics will be covered: Biodiversity and the species concept B

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  1. Chapter 13: Biodiversity • In this chapter the following topics will be covered: • Biodiversity and the species concept • Benefits of biodiversity • Humans threaten biodiversity • Biodiversity protection and Endangered Species Act • Ecosystem management and captive breeding programs

  2. Biodiversity and the Species Concept • What Is Biodiversity? • Three kinds of biodiversity • - Genetic diversity: measure of the variety of different • versions of the same genes within individual species. • - Species diversity: describes the number of different kinds of • organisms within individual communities or ecosystems. • - Ecological diversity: assesses the richness and complexity • of a biological community, including the number of niches, • trophic levels, and ecological processes that capture energy, • sustain food webs, and recycle materials within this system.

  3. What Are Species? • Underlying the commonly used definition of a species is the idea that reproductive isolation caused by geography, physiology, or behavior prevents groups of otherwise similar organisms from exchanging genes, and therefore, gives them separate identities and evolutionary histories. • Problems exist with species definitions based on reproductive isolation. • - Mating between species occurs in nature and may produce • fertile offspring. • - Difficulty in determining whether two groups that live in • different places are capable of interbreeding. • Species identification, therefore, is often based on morphological characteristics. • Determining whether similar groups of organisms can be considered separate species is highly subjective. • DNA sequencing technology is revolutionizing biological taxonomy.

  4. How Many Species Are There? • The 1.4 million species presently known represent only a small fraction of the total number that exist. • Taxonomists estimate that there may be somewhere between 3 and 50 million different species alive today. • About 70% of all known species are invertebrates. • Of all of the world's species, only 10 to 15 percent live in North America and Europe. • The centers of greatest biodiversity tend to be in the tropics, especially tropical rainforests and coral reefs.

  5. Table 13.1. -- Approximate numbers of known living species by taxonomic group Bacteria and cyanobacteria 5,000 Protozoa (single-celled animals) 31,000 Algae (single-celled plants) 27,000 Fungi (molds, mushrooms) 45,000 Multi-cellular plants 250,000 Sponges 5,000 Jellyfish, corals, anemones 10,000 Flatworms (tapeworms, flukes) 12,000 Roundworms (nematodes, hookworms) 12,000 Earthworms and leeches 12,000 Clams, snails, slugs, squids, octopuses 70,000 Insects 750,000 Mites, ticks, spiders, crabs, shrimp, centipedes, 120,000 and other non-insect arthropods Starfish, sea urchins 6,000 Fish and sharks 22,000 Amphibians 4,000 Reptiles 6,000 Birds 9,000 Mammals 4,000 TOTAL 1,400,000 Total

  6. How Do We Benefit from Biodiversity? • Food • All of our food comes from other organisms. • Plants can contribute to our food supply either as they are or as a • source of genetic material to improve domestic crops. • Unfortunately, overgrazing, forest clearing, conversion of natural • landscapes to agriculture, and other forms of disturbance are destroying potentially valuable food species and their genes.

  7. Drugs and Medicines • Living organisms provide us with many useful drugs and medicines • - More than half of all prescriptions contain some natural products. • - The value of pharmaceutical products derived from Third • World plants, animals, and microbes is estimated to be more • than $30 billion/year. • Pharmaceutical companies are actively prospecting for useful • products in many tropical countries.

  8. Ecological Benefits • Many processes all depend on the biodiversity of life. • - Soil formation • - Waste disposal • - Air and water purification • - Nutrient cycling • - Solar energy absorption • - Management of biogeochemical and hydrological cycles • Controversy exists about the role of biodiversity in ecosystem • stability. • Dramatic effects can result from removing seemingly • insignificant members of biological communities (e.g. pest control).

  9. Aesthetic and Cultural Benefits • The diversity of life on this planet brings us many aesthetic and • cultural benefits (e.g. hunting, fishing, camping, hiking, wildlife watching, and other outdoor activities). • In some cultures, nature carries spiritual connotations. • Nature appreciation is economically important. • - The U.S. Fish and Wildlife Service estimates that Americans • spend $104 billion every year on wildlife-related recreation. - Ecotourism can be a good form of sustainable economic development. • Many people believe in existence value which is simply knowing • that a species exists is reason enough to protect and preserve it. • Many religious groups have called for protecting nature because it is • God's creation.

  10. What Threatens Biodiversity? • Extinction: the elimination of a species is a normal process of the • natural world. • Human impacts on populations and ecosystems have accelerated the • rate of extinction. • Natural Causes of Extinction • More than 99% of all species that ever existed are now extinct. • Most species were gone long before humans came on the scene. • Periodically, mass extinctions have wiped out vast numbers of • species and even whole families. • - Disappearance of dinosaurs during the Cretaceous period • - During the Permian period about two-thirds of all marine species • and nearly half of all plant and animal families died out. • - Current theories suggest that these catastrophes were caused by • climate changes.

  11. Human-Caused Reductions in Biodiversity • Between 1600 A.D. and 1850, human activities appear to have been responsible for extermination of two or three species per decade. • Some estimates suggest that we are losing species at thousands of times natural rates. • Habitat Destruction • - Biggest reason for the current increase in extinctions is habitat • loss. • - Habitat fragmentation divides populations into isolated groups. • - Destruction of forests, wetlands, and other biologically rich • ecosystems threatens to eliminate thousands or even millions of • species.

  12. Hunting and Fishing • - Overharvesting is responsible for depletion of many species • - Passenger pigeon - hunting and habitat destruction. • - American Bison - harvested for their hides or tongues. • - Whales - blubber was highly prized as a source of oil. • - Fish stocks - at least three-quarters of all commercial • oceanic species are over-harvested (e.g. shark, billfish, • shrimp, orange roughy, groupers, groundfishes, sea • scallops, bluefin tuna, and red snapper).

  13. Commercial Products and Live Specimens • - In addition to harvesting species for food, we also obtain a • variety of valuable commercial products from nature • - Some forms of commercial exploitation are highly destructive • * Despite bans on trade in products from endangered • species, smuggling of furs, hides, horns, live specimens, and folk medicines amount to millions of dollars/year. • - Developing countries with the richest biodiversity are the main • sources of wild animals. • - Profits to be made in wildlife smuggling are enormous. • - Elephants, killed for their ivory tusks, are an important example • of the problems and complexities of wildlife trade. • * In 1980, there were about 1.3 million African elephants; • a decade later only half were left. • - In contrast, South African has been very successful in • conserving elephants. • * Herds have had to be thinned regularly to keep them • from destroying their habitat. • - Plants are also threatened by overharvesting (e.g. wild ginseng • and cactus). • - Trade in wild species for pets is an enormous business (e.g. • reptiles, amphibians, birds, mammals, and tropical fish)

  14. Predator and Pest Control • - Some animal populations have been greatly reduced or • exterminated because they are regarded as dangerous to • humans or livestock or because they compete with our use of • resources. • * Some animals are deliberately trapped, poisoned, or • shot (e.g. coyotes). • * Some animals are killed unintentionally by poisoned • bait or misplaced traps.

  15. Exotic organisms • - Organisms introduced into habitats where they are not native. • - One of the greatest threats to native biodiversity. • - Many examples of exotic organisms exist. • * Kudzu vine - smothers everything in its path, kills trees, • pulls down utility lines. • * Leafy spurge - reduces carrying capacity of the western • range because cattle can't eat it and it crowds out native • grasses and forbes. • * Purple loosestrife - it crowds out indigenous vegetation and reduces biodiversity in wetlands. • * Zebra mussels - have reached enormous densities • covering fish spawning beds, smothering native • mollusks in all the Great Lakes. • * Round goby - devours the eggs and fry of any species that shares their territory. One benefit is that this species voraciously eat zebra mussels. • * Asian long-horned beetles - the larvae burrow into living tree trunks where they cut off sap flow between leaves and roots. • - America also sends exotic species to other places.

  16. Diseases • - Disease organisms, or pathogens, may be considered predators. • - The balance between pathogen and host does not exist when it • is introduced into a new environment resulting in an epidemic. • * American chestnut and the introduction of fungal blight by China. • * Trout and the exotic microorganism called Myxobolus cerebralis. • Pollution • - Toxic pollutants can have disastrous effects on local • populations. • * Pesticide-linked declines of fish-eating birds and falcons • in the 1970s. • * Declines of marine mammals, alligators, and fish suggest complex interrelations between pollution and health. • * Lead poisoning in bottom-feeding waterfowl, swans, and cranes that ingest spent shotgun pellets that fall into lakes and marshes. Scavengers, such as condors and bald eagles, eat birds and mammals that have ingested lead shot.

  17. Genetic Assimilation • - Rare and endangered species may be threatened by genetic assimilation because they crossbreed with closely related species that are more numerous or more vigorous. • - Opportunistic plants or animals introduced into a habitat may genetically overwhelm local populations.

  18. Endangered Species Management and Biodiversity Protection • Parks, wildlife refuges, nature preserves, zoos, and restoration • programs have been established to protect nature and rebuild depleted populations.

  19. Hunting and Fishing Laws • By the 1890s most states had enacted some hunting and fishing • restrictions. • - Idea behind these restrictions was to conserve the resource for • future human use rather than to preserve wildlife for its own sake. • The wildlife regulations and refuges established since that time have • been remarkably successful for many species. • - White-tailed deer have increased from half a million at the turn • of the century to 14 million today. • - Wild turkeys and wood ducks were nearly all gone fifty years • ago, but through restoration efforts have been restored to several million each.

  20. Endangered Species Act • Committee on the Status of Endangered Wildlife in Canada was established in 1976. • U.S. Endangered Species Act (ESA) was established in 1973. • Endangered species: those considered in imminent danger of extinction. • Threatened species: those that are likely to become endangered, at least locally. • Vulnerable species: those that are naturally rare or have been locally depleted by human • activities to a level that puts them at risk. • Sought to identify all endangered species and populations and to save as much biodiversity as • possible, regardless of its usefulness to humans. • Regulates a wide range of activities involving endangered species. • - Taking (harassing, harming, pursuing etc...) either accidentally or on purpose. • - Importing into or exporting out of the United States. • - Possessing, selling, transporting, or shipping. • - Selling or offering for sale any endangered species. • Violators of ESA are subject to fines up to $100,000 and one year imprisonment. • Currently, the United States has 1500 species on its endangered and threatened species list • and about 500 candidate species waiting to be considered. • - Although invertebrates make up about three-quarters of all known species, they • account for only 9 percent of those deemed worthy of protection. • Currently, Canada has designated a total of 46 endangered and fifty threatened species. • Listing of new species in the United States is slow, taking several years from the first petition • to final determination. • Originally intended to protect only a few charismatic species, it also will protect less celebrated species which could be indicators of environmental health.

  21. Table 13.4 -- Endangered and threatened species, U.S. and foreign, listed by USFWS Mammals 331 Birds 267 Reptiles 112 Amphibians 22 Fish 113 Invertebrates 135 Plants 520 Source: Data from United States Fish and Wildlife Service, 1999

  22. Recovery Plans • Once a species is listed as endangered, the Fish and Wildlife Service is required to • prepare a recovery plan detailing how populations will be rebuilt to sustainable levels. • The United States currently spends about $150 million per year on endangered • species protection and recovery. • Some recovery plans have been very successful. • - American alligators - Florida alone estimates that it has at least 1 million. • - Bald eagles - in 1999 were declared recovered and removed from the list. • Opponents of the ESA have tried to require that economic costs and benefits be • incorporated into endangered species planning. • - An important example is that of the northern spotted owl whose protection • depends on preserving old-growth forest in the Pacific Northwest. Economists • estimate that saving a population of 1600 to 2400 owls would cost $33 billion, • with most of the losses borne by local companies and residents of Washington • and Oregon. • - An even more costly recovery program may be required for Columbia River • salmon and steelhead endangered by hydropower dams and water storage • reservoirs that block their migration to the sea.

  23. Private Land and Critical Habitat • Private land is essential in endangered species protection. • Eighty percent of the habitat for more than half of all listed species is on nonpublic • property. • Many people are resistant to restrictions on how they use their own property to • protect what they perceive to be insignificant or worthless organisms. • - This is particularly true when the land has potential for economic • development. • Habitat conservation plans (HCP): landowners are allowed to harvest resources or • build on part of their land as long as the species benefits overall. • - Purpose of HCPs is to try and to avoid controversy's like the northern • spotted owl. • - About 250 HCPs have been approved and 200 more are in progress. • * Total of 7 million ha of land are covered by these plans. • - Scientists and environmentalists often are critical of HCPs, claiming these • plans often are based more on politics than biology.

  24. Reauthorizing the Endangered Species Act • The ESA officially expired in 1992. • Since then, Congress has debated many alternative proposals from • outright elimination to substantial strengthening of the act. • Proposals for a new ESA generally fall into one of two general • categories. • - Environmentalists encourage an ecosystem and habitat protection approach rather than focusing on individual • species. • - ESA opponents want to allow exceptions to critical habitat designation. Under their proposals, only the least costly, most cost effective or least burdensome measures would be taken to protect endangered organisms.

  25. Minimum Viable Populations • A critical question in all recovery programs is the minimum population size • required for long-term viability of rare and endangered species. • A small number of individuals can undergo catastrophic declines due to • environmental change, genetic problems, or simple random events when isolated in a limited geographic range. • - Described as island biogeography in the work of R. H. MacArthur and E.O. • Wilson in 1967 who proposed that species diversity is a balance between colonization and extinction rates. • * An island far from a population source has a lower rate of • colonization than a nearer island because it is harder to reach. • * A large island can support more individuals of a given species and • is less likely to suffer extinction due to natural catastrophes, genetic • problems, or demographic uncertainty - the chance that all members • of a single generation will be of the same sex.

  26. For many species loss of genetic diversity causes a variety of harmful effects that • limit adaptability, reproduction, and species survival. • - Founder effect: occurs when a few individuals establish a new population. • - Demographic bottleneck: arises when only a few individuals survive some • catastrophe. • - Genetic drift: reduction in gene frequency in a population due to unequal • reproductive success. • - Inbreeding: mating of closely related individuals which can result in random, • recessive, and deleterious mutations. • Not all species are harmed by the lack of genetic diversity (e.g. the northern • elephant seal)

  27. Habitat Protection • A growing number of scientists, land managers, policymakers, and developers have • been making the case that it is time to focus on a rational, continent-wide preservation of ecosystems that support maximum biological diversity rather than a • species-by-species battle for the rarest or most popular organisms. • A leader of this new form of conservation is J. Michael Scott, who was the project • leader of the California condor recovery program in the mid-1980s and had spent ten years working on endangered species in Hawaii. • - Scott discovered that even Hawaii has many vegetation types completely • outside of natural preserves. • - The gaps between protected areas may contain more endangered species than are preserved within them. • - Gap analysis: approach in which conservationists and wildlife managers look for unprotected landscapes that are rich in species. • Conservation biologist, R.E. Grumbine suggests four remanagement principles for • protecting biodiversity in a large-scale, long-range approach. • - Protect enough habitat for viable populations of all native species in a given • region. • - Manage at regional scales large enough to accommodate natural disturbances. • - Plan over a period of centuries so that species and ecosystems may continue to evolve. • - Allow for human use and occupancy at levels that do not result in significant • ecological degradation.

  28. International Wildlife Treaties • The 1975 Convention on International Trade in Endangered Species • (CITES) was a significant step toward worldwide protection of endangered flora and fauna. • - Regulated trade in living specimens and products derived from • listed species. • - Species are still smuggled out of countries where they are • threatened or endangered and documents are made to appear • they have come from areas where the species are still common. • - Difficult to regulate in developing countries where wildlife is • disappearing most rapidly.

  29. Zoos, Botanical Gardens, and Captive Breeding Programs • Records of wildlife and exotic plant collections date back to the • beginning of history. • In some places low-life circuses and seedy roadside tourist • attractions still exhibit sad collections of animals in cramped, • unhealthy cages. • In developed countries, cruel and callous conditions have been • eliminated by animal welfare laws. • Most modern zoos and wildlife parks now keep animals in clean and • humane conditions. • Many animals living will live longer and raise more young than they • would in the wild. • Valuable genetic traits are preserved in repositories such as botanical • gardens for rare and endangered plant species. • - May be reintroduced into native habitats after being cultivated • in these gardens.

  30. New Zoos and Game Parks • Large enclosures, realistic terrain, and multi-species groupings allow • more normal social behavior and encourage reproduction. • Under these new conditions, zoos can be important places for • scientific research in wildlife biology. • Today in the United States some 150 municipal zoos provide the • only experience that people will ever have with wild animals. • 110 million visitors per year learn about nature through visits to • zoos.

  31. Captive Breeding and Species Survival Plans • Most mammals in North American zoos are now produced by • captive breeding programs. • These programs have limitations in that not all animals reproduce • well in captivity. • Worldwide, zoos house about 500,000 individual animals, but only • about 900 species total. • - Few of these animals are maintained in populations large • enough to preserve the species indefinitely if wild • populations were lost. • To reduce genetic problems, zoos often exchange animals or ship • individuals long distances to be bred.

  32. Saving Rare Species in the Wild • The Minnesota Zoo and the Ujung Kulon National Park in • Indonesia are trying to save the world's few remaining • Javanese rhinos in their native habitat rather than bring them back to the zoo.

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