Chapter11

Chapter11 - Conserving Biodiversity Includes material from...

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Unformatted text preview: Conserving Biodiversity Includes material from Ch 6 Notice: chapters are not in numerical order from this point on in the semester. Consult your syllabus regularly. After studying Ch 11 you should Recall or learn definitions (biodiversity, species, hot spot, ESA, CITES, spp richness, spp evenness, extinction, gap analysis, captive breeding) List and understand threats to biodiversity (habitat fragmentation/destruction, exotic spp, overharvesting, pest mgmt) Understand the legal mechanisms for helping endangered spp recover Biodiversity is decreased when humans size of a population range of a species isolate a population from nearby popns alter conditions of environment introduce an exotic species that modifies habitat or competes w/ existing spp Memorize these! Biodiversity and Speciation Biodiversity is the total amount of biological variation in a given area. Necessary for stability of envmtl systems. Necessary for popns to be able to change when the envmt VIMP ! changes (i.e., evolve). For every type, popn or sz of area = bioiversity. Genetic Diversity - measures the naturally occurring differences in DNA of organisms. Species Diversity measures the variety of different kinds of organisms within a community Genetics & Minimum Viable Populations Minimum Viable Population (MVP) is the minimum population size required for long-term viability of a species Island biogeography - Small islands far from a mainland have fewer terrestrial species than larger, closer islands 50-500 Rule most popns need more than 50 and at least 500 indiv to avoid deleterious effects of inbreeding - MacArthur and Wilson proposed that species diversity is a balance between colonization and extinction Minimum Viable Populations Diversity is lost in small populations due to: Founder Effects - a few individuals start a new population Bottlenecks - few individuals survive a catastrophe Genetic Drift - random changes in gene frequency Inbreeding - mating of related individuals Species Species - Organisms of the same kind that are able to breed in nature and produce fertile offspring Over 1000s of generations, reproductive isolation prevents gene exchange and gives rise to new species Hybridization is common in nature making it difficult for us to parse recently evolved spp. Species identification often is based on morphological (what it looks like) characteristics, but molecular (genetic) is more precise How Many and Where Currently ~1.4 million species identified Probably >30 million insect species Probably 10 million species on ocean floor Invertebrates make up >70% of all known species, and probably most of the yet-tobe-discovered species Tropical rainforests, Mediterranean, & coral reefs are biodiversity hotspots North America and Europe only contain 10-15% known spp Benefits of Biodiversity Ecological - many spp have crucial roles in ecosystem function: bacteria R essential to nutrient cycling keystone spp modify envmt for other spp forests aid H20 retention, prevent erosion, temper climate, cycle nutrients, and absorb solar E Aesthetic makes us feel good to experience w'life diversity hard to put a monetary value on sights and sounds that people find enriching More Benefits of Biodiversity Utilitarian genetics: need wild relatives of crops pharmaceuticals: > 50% from wild organisms subsistence items for indiginous peoples - o/wise they must import pollution control: bacteria and plants remove toxins from air, H20, & soil (Eco)tourism research: e.g., armadillo (Dasypus novemcinctus), horseshoe crab (Limulus polyphemus) More Benefits of Biodiversity Moral all beings have intrinsic value and should be conserved just because they exist intergenerational equity - we don't have the right to use up or destroy something making it unavailable to future generations Free services to us and nature O2 CO2 clean ground water maintain local climate More Benefits of Biodiversity Ethics Power begets responsibility Food, drugs, knowledge edible fruits & nuts genes needed to improve domestic crops 50 % prescrip. and nonprescrip. drugs made with medicinal chemicals from wild plants barnacle cement good for gluing fillings in teeth! Threats to Biodiversity Extinction - Elimination of a species Natural process - in undisturbed ecosystems, background rate ~ one species per 4-10 yr - 99% of all species that ever existed are extinct Anthropogenic - human activity that disrupts ecosystem, or food web, or co-evolution resulting in extinction of ~ 10,00020,000 / yr 1. Habitat destruction and fragmentation divide populations into isolated groups vulnerable to catastrophic events 2. Hunting and fishing Natural Extinctions are a result of the normal evolutionary process Natural Reductions in Biodiversity Loss Genetic Variation peripheral pop'ns have too small numbers and so they inbreed; can't respond to environmental changes if pop'n goes below critical popn size (a.k.a. minimum viable population) habitat Competitive Exclusion - competition for food and Random Events - major environmental upheaval; species are preserved or annihilated at random; those pop'ns with larger geographic range are less prone to extinction habitat; characters enhancing survival do so in ways unrelated to causes of their evolution in the first place "Different Rules" - the case of radically altered Anthropogenic Reductions in Biodiversity Habitat Fragmentation Human activity results in patches that R isolated from one another by inhospitable matrix Rivers and streams naturally fragment habitats Anthropogenic Reductions in Biodiversity Commercial Products and Live Specimens Wildlife smuggling Annual pet trade in wild species e.g., in US we buy: - 2 million reptiles - 1 million amphibians and mammals - 500,000 birds - 128,000,000 tropical fish (75% captured using cyanide above coral reefs, 25% dipped or blasted from the Amazon) Anthropogenic Reductions in Biodiversity Predator and Pest Control - many animal populations have been greatly reduced or exterminated because they are regarded as dangerous to humans or livestock (prairie dogs, coyotes, bobcats; then as a result, other associated spp decline e.g., ferrets) Superstition many animal spp are hunted and killed purely to eliminate them (snakes, sharks, bears, rhinos, snapping turtles) and most of these play key roles in their ecosystems Anthropogenic Reductions in Biodiversity Exotic Species Introductions - Organisms introduced into habitats where they are not native (a.k.a. Biological Pollution) Kudzu Vine Purple Loosestrife Zebra Mussel Asian Long-Horned Beetle Extinction in general Background Fewer than 1 per year ~ 1 / 4 years 10,000 - 100,000 per year ~ 50 - 200 / day Anthropogenic Natural Small populations genetic drift & inbreeding genet. variat'n so can't adapt Loss genetic diversity Competitive exclusion Random events (small popns) Accelerated Habitat alteration & Pollution Commercial hunting Sport & subsistence hunting Exotic species Pest/predator control Pet trade Research Superstitious beliefs Anthropogenic (Accelerated) extinctions R caused by 30% 21% 18% 16% 7% 5% 2% 1% Habitat alteration Commercial hunting Sport/subsistence hunting Exotic species Pest/predator control Pet trade/research Superstitious beliefs Pollution urban sprawl, farming, dams, roads, timbering, mining, etc. elephant, whale, tiger, sturgeon alters ecosystem by removing predators or genetic diversity compete for food & habitat, predator, pests, parasites hitchhike on them chemicals such as DDT; banned in US but not elsewhere fishes, cactus, orchids, primates; 5-50X as many die en route coyote, rattlesnake, shark, bear, rhino global warming, acid deposition, toxic metals Biodiversity Protection Hunting and Fishing Laws By 1890's, most states had enacted some hunting and fishing laws Endangered Spp Act (1973) "provide means whereby the ecosystem upon which endangered species and threatened species depend may be conserved" It's illegal to buy sell or trade T&E spp: - Harvest (harassing, harming, pursuing, hunting, shooting, killing, capturing, or collecting) either accidentally or on purpose - Possess - Import into or Export out of the US - Sell - Transport or Ship U.S. Endangered Species Act Requires establishment of federal programs to protect habitat; listed spp must have recovery plan All federally-funded or permitted projects that could affect T&E species must be reviewed US currently has ~1,300 spp on its T&E lists, and ~ 500 candidates waiting for consideration Reflects human interests not actual status, e.g., invertebrates make up >70% of all known species, but only 9% of T&E list Listing process is extremely slow Most funds R expended in litigation, not habitat restoration or de-listing International Wildlife Treaties Convention on International Trade In Endangered Species (CITES) - 1975 Regulate trade in living specimens and products derived from listed species Cites lists US lists State lists Groups of concern Endangered - without concerted efforts it will become extinct due to human activities or natural causes Charismatic megafauna - glamorous, cute, most visible of endangered species that are targeted for conservation after an ecosystem has been severely altered Keystone - unobtrusive, rare, less conspicuous species upon which an entire ecosystem depends Threatened - still abundant but declining so rapidly it is likely to become extinct Vulnerable - is naturally rare or have been locally depleted to a level that puts it at risk of extinction Management Strategies for Fisheries Only 20 spp make up the world's commercial seafood harvests. Many of the 20 spp of fish and shellfish are overharvested. Many fish (& shellfish) first use rivers, then intertidal, then pelagic waters Fish (& shellfish) don't "respect" political boundaries Major harvesters R US, Japan, China, Russia, Chile Most coastal nations claim a 200 mile EEZ (exclusive economic zone) off their coasts. In this zone, they regulate seafood harvests in primarily open access systems. Some agencies implement ITQs (individual tradable quotas). Outside the EEZ is global common property. Management Strategies MSY VIMP ! Maximum sustained yield is is the point on a logistic growth curve that indicates exactly 50% of carrying capacity (CC) BUT, you don't know CC until it is reached, many things affect CC and so it changes from year to year; you must estimate CC exactly and estimate 50% CC exactly; you must harvest exactly 50% of CC; any more leads to a in the pop'n next yr! Most fisheries have "crashed" because management is for MSY (maximum sustainable yield see Chapter 13). Better strategy would be to manage for OSY (optimum sustainable yield) which includes not just the logistic gth curve for the sp but ecological and envmtl info for that sp, its predators, and prey. The very best strategy would be to manage for OSP (optimum sustainable production) which usually precludes harvesting wild populations for commercial purposes. If it's needed for commercial purposes, it should be cultivated, not harvested from the wild. Biodiversity Protection Strategies ESA officially expired in 1992. Reauthorization proposals focus on strategies that protect ecosystems by supporting maximum biological diversity rather than species-by-species approach. Some oppose ESA because of "takings" i.e., the law could take away their rights to use their property to prosper in any way they see fit. Gap Analysis - Conservationists and wildlife managers look for unprotected landscapes that are rich in species. Such gaps often contain more T&E spp than are in nearby parks and preserves Ecosystem-based mgmt instead of managing for MSY, agencies manage using data on predator-prey and habitat quality Biodiversity Map & Gap Analysis Good: linking areas w/ spp = conserv. potential. Bad: Park boundaries R generally chosen based on political or aesthetic priorities not biological importance Biodiversity Protection Strategies Reserves set aside worldwide biodiversity regions for protection in native habitats buy back lands from colonists extractive reserves for sustainable harvest zone without intense human activity (i.e. timbering or agriculture) separating a protected area from an unprotected areas connections between "ecological islands"; especially effective for small parks & refuges; links fragmented habitats to allow migration and facilitate random breeding Buffers Corridors Last Resort Strategies for any Living Resource Zoos and Botanical Gardens (the last resort) captive breeding programs in zoos and botanical gardens; most mammals in NA zoos are produced from captive-breeding programs; some zoos participate in reintroduction programs; false sense of security so wild pop'ns generally continue to Germ Plasm Repositories (the "really" last resort) save gametes or seeds and roots in "cold storage" until we figure out a way to restore the habitat ...
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Chapter11 - Conserving Biodiversity Includes material from...

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