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130 Cards in this Set
- Front
- Back
Population
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A group of organisms of a single species that live together in a particular area
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Studying populations
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Genes
Modes of reproduction Behavior Demographics oSize, age structure, density, distribution |
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Population distribution
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How are individuals distributed?
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Population growth
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How fast does the number of individuals increase?
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Population size
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What factors regulate the number of individuals
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Population density
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How many individuals per unit area
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Clumped Population Distribution
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Patchy availablity of resources; ex.nutrient "hot spots"
Social or clonal organisms; ex. flocks of birds, clumps or grass, aspen trees; saftey in numbers Reproductive characteristics; Parents with young, plants with seeds; Clonal |
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Nearly Uniform Population Distribution
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Rare in most environments
Uniform distribution of resources Competition causes organisms to be equally spaced; Ex. Desert shrubs (creosote bush), some birds |
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Random Population Distribution
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Uniform distribute of resources
Organisms spaced without regard to other; Ex. Plants with small easily-dispersed seeds Competition is NOT an issue |
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Factors that Determine Species Distribution
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Evolution
Continental drift Suitable habitat o Physical environment o Biotic environment |
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Continental Drift (Species Distribution)
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Movement of the continental plates relative to each other
Ex. Southern beech tree evolved when SA, Ant & Aus were still connection → Continents drift → populations became widely separated Biogeography: the study of geographic distribution of organisms |
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Physical Environment (Species Distribution)
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Temperature
Rainfall Nutrient availabitiy Light Wind o Ex. Saguaro → only in spots where temperatures don’t remain below freezing for 36 hours straight |
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Biotic Environment (Species Distribution)
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Competition from other species of barnacles prevents it from moving south
Ex. Barnacle (Balanus balanoides) should be found 1600km south to where the suitable temp ends → competition prevents |
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Factors Affecting Population Growth
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Increases: Births, Immigration (In)
Decreases: Death, Emigration (Exit) |
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Calculating Population Growth
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G = number of individuals per unit time
G = rN N = number of individuals in a population t = time r = rate of population increase per unit of time o [individual in – individials out] / time o [(birth + immigratio) – (death + emigration)] / time |
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Models of Population Growth
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Exponential Growth
Logistic Growth |
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Exponential Growth
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Rapid population growth in which a population increase by a constant proportion form generation to the next (J curve)
Resources (food, water, space, etc.) are unlimited Growth rate increase over time because there are more individuals able to reproduce Occurs until resources become limiting, then growth will slow down |
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Carrying capacity (“K”)
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The number of individuals that an area is able to support indefinitely
The growth rate of a population may be exponential until it approaches the carrying capacity o Then growth rate will slow to zero Can change over time o Environmental conditions change o Food and water supply o Space availability |
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Logistic growth
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• Occurs in populations with resource limitations
• Occurs when the population approaches the carrying capacity (K) • Growth rate slows to zero (S curve) |
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Density-dependent factors
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Depend on the size of the population
o Increase competition for resources as population increases o Crowding o Parasites o Pathogens Ex. Grow and crash reindeer in Alaska, no natural predator |
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Predator-Prey Cycles
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Prey population increase
Predator population increase Predators overfeed on prey Prey population decrease Predator population decrease Cycle repeats |
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Population Demography
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Demography = the study of the characteristics of human populations
o Size o Growth o Density o Distribution o Vital statistics |
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Human Population Growth
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• >6.4 billion now
• 8.9 billion by 2050 |
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Why Has Our Population Skyrocketed
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We expand into new habitats and climates
o Clothing, fire, shelters, air conditioning We’ve increase our carrying capacity o Increased food supply We’ve side-stepped limiting factors o Improved medical practices and sanitation |
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Drastic Population Control Measures (China)
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One-child policy introduced in 1979
Enforced via $ fines Prevented ~300 millions • Less demand on natural resources • Better healthcare for women • Standard of living increase overall Controversial • Female infanticide • Current gender imbalance |
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Community Ecology
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Community: all the organisms living in a given area
o Communities vary in species diversity o Based on species richness (# of species), and relative abundance (proportion of each species) Based on interspecific interactions (+/-/0) Dominant Species Keystone Species |
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Dominant Species
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Increased # of individuals, greatest biomass or some other indicator of importance
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Keystone Species
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Larger impact on a community than expected relative to its abundance or size
Extinction/removal of a keystone stpecies would lead to extinction of other species in community Ex. Black-talied prairie dogs in Prairie Ecosystem |
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Interspecific Interactions
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Symbiosis: host species and symbiont maintain a close association
o Commensalism (+/0) o Mutualism (+/+) o Parasitism/Parasitoids (+/-) Predator-prey Herbivory |
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Commensalism
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Symbiont benefits (+)
Host is unaffected (0) Rare; occurrence is debatable Ex. Cattle egrets eat insects stirred up by grazing cattle |
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Mutualism
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Symbiont benefits (+)
Host benefits (+) Change in either species is likely to affect survivial of the other Ex. Lichen = algae + fungi Ex. Mycorrhizae = plants + fungi Ex. Plant interactions with animals for pollination and seed dispersal |
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Parasitism
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Parasite benefits (+)
Host is harmed (-) Many parasites are adapted to specific hosts o Ex. dodder (plant parasite); ticks, fleas, tapeworms Social parasites take advantage of behaviors o Ex. nest parasitism → laying eggs in nest of diff. species |
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Parasitoids
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Adult parasitoid inserts eggs into host species
Eggs develop inside host Devour host from inside out as they grow Ex. Parasitoid wasps → caterpillar, aphids, spiders, beetles, etc. scene from “Alien” |
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Predator-Prey
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One species get fed (+)
Other species gets killed (-) Ex. Carnivores, herbivores (overgrazing) |
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Herbivory
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Animal feeds on a plant
Plant is not killed Plants cannot escape o Must evolve chemical defenses o Become toxic or distasteful o Cause counter-adaptation in herbivores Plant can benefit by seed dispersal |
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Development of Communities
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Communities are not constant
Succession: o Change in communities over time o Gradual colonization of an area by organisms o Primary vs. secondary Climax community: o A theoretical, stable ultimate community o BUT, disturbance is always possible! |
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Primary Succession
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Occurs after disturbance intense enough to remove all living organisms, soli, and soil-development processes
Initiated by o Glaciation o Lava flows o Severe wild fires o Pavement |
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Secondary Succession
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Occurs after disturbance that is NOT intense enough to kill all plants, and soil is not removed
Initiated by: o Abandonment of agricultural land o Fire o Flood Much fast than primary succession o Soil present o Seeds in soil o Existing roots |
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Age Distribution Graphs
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Indicate relative number of individuals of a species of different ages in a population
Indicates most common age of species Predict species composition of population in the future |
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Types of Biodiversity
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Genetic
Species Ecosystem |
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Genetic Biodiversity
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All of the different genes within individual organisms
Both within species and between species |
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Species Biodiversity
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The number and distribution of species in a given location
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Ecosystem Biodiversity
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The differences in habitats
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Biodiversity #1's
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Insects most biodiverse species; many plant species yet to be identified
Tropics most biodiverse environment o More sun and rain o Longer growing season o Diversity of habitats o Longer history o Species diversity is self-reinforces; increased plant diversity = increased herbivore diversity |
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Threats to Biodiversity
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“The cutting of primeval forest and other disasters, fueled by the demands of growing human populations, are the overriding threat to biological diversity everywhere" E.O. Wilson, The Diversity of Life
Sparknotes: forests are being cut but humans who demand more and more of the enviroment, effectively hurting biodiversity |
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Conservation Biology
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Survey full range of biological diversity
Preservation o Set aside natural areas to remain undeveloped o Globally, an area only ~half the size of U.S. is currently protected as natural areas Resource conservation o Management scheme based on balance “multiple uses” of natural resources → Agricultre, industry, preservation, recreation Evolutionary/ecological view o Recognition that ecosystem processes are needed to maintain the biosphere |
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Economic reasoning for Biodiversity
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Crops
Fibers Medicines Tourism Pollination of our crops Natural pest controls Extinction – loss of genes that may have been useful to us |
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Scientfic reasoning for Biodiversity
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Loss of biodiversity upsets ecosystem function, eliminating ecosystem services; Clean water, clean air, fertile soils
Genetic diversity allows organisms to adapt to changing environment conditions |
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Ethical reasoning for Biodiversity
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All organisms play an important role in their ecosystem
Moral and aesthetic obligation to conserve biodiversity |
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Taxol
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Yew trees are very rare in the NW because of logging
~600,00 trees are needed to treat all patients; $1,800 per single dose Dr. Rodney Croteau (WSU) first identified the gene responsible for making taxol Looking for ways to make synthetic taxol at lower cost |
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Invasive Species
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Definition:
o Organsims that have evolved elsewhere and have been purposefully or accidentally relocated Terms applied: o Invasive o Non-native o Alien o Exotic o Noxious weeds: Weeds that are so widespread that they threaten crops, livestock, or native species |
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Why are Invasive Species invasive?
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Invasive species often find no natural enemies in their new habitat
May have special adaptations that make them better able to access resources than native species Result: they spread quickly |
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How do Invasive Species get around?
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Accidential introduction
o Global human travel Deliberate introduction o Erosion control (ex. kudzu) o Sport hunting/fishing (ex. brown trout) o Landscaping; Ornamental plants, seed catalogs o Reminds us of home o Because they’re pretty o Trade in unusual pets o Ship ballasts |
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Threats of Invasive Species
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Can eat, compete, or mate with native species
Invasive plants can: o Smother native vegetation o Increase frequency of fires, floods, other disturbances o Out-compete crops at a cost of $7.5 billion annually Diseases and parasites they bring can harm organisms that they did not evolve with o Natives lack adaptation against diseases/parasites Can poison native species |
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Scotch Broom (Cytisis scoparius)
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Pea family
Well-behaved in native range (Europe) Introduced to US to control erosion o Form dense strands o Crowd out native species o Destroy wildlife habitat |
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Kudzu
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Pea family
From Japan, Asia Introduced to US in 1870’s for erosion control and forage o Grows 60 m/year o Goats help, but also eat other plants o A fungus currently being tested as a biocontrol |
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Tamarisk/Tamarix
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From Eurasia and Africa
Introduced to US because of pretty red flowers, erosion control, windbreak Invasive along waterways in American West o Very long tap roots o Outcompetes native plants for water o Drains water from aquifers o May be controlled by a leaf feeding beetle (in experimental stages) |
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Cheatgrass
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Native of Mediterranean
Introduced accidentally to US in late 1800’s o Established on disturbed sites, produces many seeds o Plant dries in early summer, creating a fire hazard o Seeds are sharp! Can penetrate animal tissues o Cheatgrass invasion affects fire frequency |
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Brown Trout
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Native to Europe and Asia
Introduced to US in 1880’s as a game fish Outcompete native brook, golden, and rainbow trout Can live in warmer water than native trout Programs have been implemented to preserve natives, encourage harvesting browns |
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Cane Toads
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Can be over 1 foot long, weight 3 lbs.
Natural Range: Southern US to South America o 20 toads / 100 meters Introduced into Australia in 1935 to control scarab beetles that destroyed sugar can o Up to 2000 / 100 meters Toxic glands can poison pets and human o Tadpoles toxic too Prey on native fauna Prey on pets |
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Economic Impact of Invasive Species
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~50,000 non native species in US (US Fish & Wildlife)
~ 4,300 considered invasive Invasive species cost >$137 billion annually in economic losses! o Crop losses o Reduced commercial and sport fishing o Reduced wildlife watching o Increased operating costs Not to mention losses of native species |
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Chemical Control (Invasive Species)
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Pesticides
o Kill invasive species, but also natives o Invasive species can develop resistance o Expensive |
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Mechanical Control (Invasive Species)
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Physically remove invader
o Expensive o Labor intensive |
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Biological Control (Invasive Species)
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Introduce a natural enemy from invader’s range
o Enemy can also become an invader |
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Ecological Control (Invasive Species)
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Modify the environment (ex. rabbit proof fence in Australia)
o Impacts native species too |
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Controlling Invasive Species
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Chemical Control
Mechanical Control Biological Control Ecological Control Birth Control |
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Ecology
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The scientific study of organisms and the environment in which they live
o Historically a descriptive science o Recently become an experimental science Driven by need to understand how our activities are affecting our planet Multidisciplinary o Covers all aspects of biology as well as many physical sciences o Huge number of variables o Impossible to control variables Components o Biotic (living components) o Abiotic (non-living components) |
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Ecosystems
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Natural ecosystems are self-sustaining systems which include living organisms and the physical elements of the environment
Critical factors = energy flow and chemical cycling o Focus of ecosystem studies is to understand energy flow and how matter cycles o Especially important as we try to study environmental change by human activites o Ex. The Carbon Cycle |
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Ecological Studies
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Make hypotheses
Test them using lab and field experiments Mathematical models and computer simulations |
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Major Abiotic Factors Affecting Organism Distribution
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Environmental Temperature
Water Sunlight Wind Rocks and Soil Periodic Disturbances |
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Abiotic Factors: Environmental Temperature
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Affects biological processes and body temperature
Most enzymes function 0-45 degrees C |
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Abiotic Factors: Water
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Essential for life
All terrestrial organisms face the problem of desiccation (extreme dryness, drought like condition) |
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Abiotic Factors: Sunlight
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Necessary for photosynthesis
Too much light can cause mutations Different plants have adaptation to deal with different light levels |
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Abiotic Factors: Wind
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Amplifies the effects of temperature
Increase heat loss by evaporation (wind chill) |
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Abiotic Factors: Rocks & Soil
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Physical structure, pH, and mineral compostition of soils limit the distribution of plants
Affect disribution of animals that feed on them Soil affects whether animals can burrow or plants can take root |
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Abiotic Factors: Periodic Disturbances
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Catastrophic events can devastate biological communities (ex. fire, floods, hurricanes, volcanic eruptions)
Re-colonization or repopulation by survivors, but community structure is dramatically altered Many organisms have adapted to frequent disturbance such as fires (ex. lodgepole pine seeds germinate after a fire) Not always bad; some normal for most communities because it creates variation in the habitat and can help maintain species diversity Small fires prevent accumulation of “fuel” on forest floor Fire prevention can lead to build-up of fuel resulting in larger more damaging fires o Ex. Yellowstone → lots of suppression lead to large scale fir in ’88, regeneration began the next year |
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Abiotic Factors: In WA
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Precipitation from Pacific Ocean
Wind Moves precipitation over Olympic Range Increases moisture deposited on west side of Cascades Range; decreases precipitation on east side of Cascades (rain shadow effect) o Temperature (related to elevation) o Topography o Wind o Water |
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Trophic Levels
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Feeding relationships that determine the paths of energy flow and chemical cycling
3-5 trophic levels in an ecosystem o Primary producers (photosynthetic autotrophs) o Primary consumers (herbivores) o Secondary consumers (carnivores that eat herbivores) o Tertiary consumers (carnivores that eat carnivores) o Decomposers (feed on waste from all other levels) |
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Food Chain
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Pathway of food consumption
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Trophic Level
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Each level of consumption in a food chain
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Food Web
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Interconnected food chains
Some organisms can be both primary and secondary consumers |
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Trophic Levels: Toxins
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Toxins become more and more concentrated with each successive trophic level of the food chain
Biomagnification (aka bioaccumulation) Toxic chemicals are dumped intentionally or unintentionally into ecosystems o Many are not biodegradable o Persist for years or decades Organsims acquire toxins from food or water o Some are metabolized and excreted; many accumulate in tissues (ex. DDT, PCB’s, Mercury) |
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DDT
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Was used in the US to kill mosquitoes and agricultural and household pests
Lipid soluble, accumulates in fatty tissues Causes loss of calcium in egg shells; eggs break during incubation Banned in ’72, but still in use in many countries Biomagnification → increase of 10 million times from water to fish-eating birds |
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Primary Productivity
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Photosynthetic activity in the ecosystem
The only energy input in most ecosystems is sunlight Primary producers determine the amount of energy available to the rest of the ecosystem |
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Secondary Productivity
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Rate at which energy consumed is converted into consumer's biomass
Only ~1/6 of calories conusmed add biomass to the next higher trophic level Large energy losses at each level in the chain 80-95% is lost between each level Only ~1/1000th of energy fixed by a primary producer reaches a tertiary consumer |
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Moving of the Food Chain
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Decrease in number of organisms
Increase in space requirements Only 3-5 trophic levels can be supported Implication for the human population; a vegetarian diet makes more efficient use of land and energy that a meat-based diet |
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Human Impacts on Ecosystems
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Fire Suppression
Logging Depletion of Water Supplies Air Pollution Air Pollutants & Ozone Acid Precipiation Global Warming |
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Impacts on Ecosystems: Fire Suppression
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Forest fires are a normal abiotic factor in ecosystems
Periodic fires release nutrients & create diverse habitats Leads to a build-up of dense forests; fuel for the next fire |
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Impacts on Ecosystems: Logging
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Clear-cutting contributes to soil erosion
Nutrients are bound up trees Logging removes the nutrients from the area Some logging companies now leave behind bark and wood chips |
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Impacts on Ecosystems: Depletion of Water Supplies
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~ half of US population gets water from underground sources (aquifers)
Water is being pumped out of aquifers faster than it is replaced Pullman had 20 artesian wells in late 1800's Grand Ronde aquifer had so much water that it rose to surface; aquifer dropping 1-3 ft/year Now only a few artesian wells in Pullman |
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Impacts on Ecosystems: Water Pollution
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Natural aquatic systems are low in mineral nutrients, limits phytoplankton/algal growth
But sewage, factory waste, livestock runoff and fertilizer leaching increase nutrient levels in aquatic systems |
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Global Warming a Hoax?
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Dr. James Hansen (NASA) 2008: Bush administration "edited" his climate reports to make global warming seem less threatening
Union of Concerned Scientist Report 2008: Exxon Mobile has been paying scientist to downplay global warming |
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Impacts on Ecosystems: Increased Nutrient Levels in Aquatic Systems
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Especially in N
Large increasd in growth of photosyntheic organisms Large increase in weed growth in aquatic systems Primary producers dies, decomposers consume all O2 in the water (eutrophication) Nitrates in water supplies can cuase "blue baby syndrome" (reduction in O2 carrying capacity of blood) |
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Impacts on Ecosystems: Air Pollution
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Human activities have ~ doubled worldwide supply of fixed N due to use of fertilizer, cultivation of legumes, and burning
o May increase NOx’s (may be most damaging component of air pollution not carbon emissions) in atmosphere o Contribute to atmospheric warming o Depletion of ozone o Acid rain |
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Impacts on Ecosystems: Air Pollutants & Ozone
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Life on Earth is protected from damaging effects of UV radiation by a layer of O3 (ozone)
Ozone layer has been thinning since 1975, probably because of accumulation of CFC's (chlorofluorocarbon's) used in refrigeration, aerosol cans, manufacturing processes CFC's reduce O3 to O2, reduction in O3 layer leads to increase UV radiation leading to increase skin cancer and cataracts |
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Impacts on Ecosystems: Global Warming
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Human activities may be causing climate change by increasing [CO2] in the atmosphere
Increased since Ind.Rev. because of burning fossil fuels and compounded by deforestation CO2 absorbs infared radiation and slows its escape from the Earth; likely to cause planetary warming Stop global warming = wrong; stop the human contribution to the accelerated rate of global warming = right |
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Impacts on Ecosystems: Acid Precipitation
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Caused mainly by combustion of fossil fuels; releases SOx's and N
React with atmospheric water to produce sulfuric and nitric acids whcih fall back to Earth as precipitation By changing pH of soil and water, acids can kill plants and aquatic organsims |
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Habitat Fragmentation
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Natural habiats are broken into small fragments by agriculture, forestry, mining, urbanization, roads
Habitat fragments are too small to support large predators Small herbivore populations increase causing decrease in plant population Fragmented populations experience decrease geneitc diversity Large trees in habitat fragments are more susceptible to wind exposure, parasites, and water stress |
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Extinction
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A natural phenomenon that has been occuring since life evolved
Current rate of extinction is what underlies biodiversity crisis 13% of bird species threatened with extinction (1,183 species) 20% of freshwater fish recently extinct or endangered 200 plant species extinct; 730 endangered or threatend Half of current species may be extinct by 2100 |
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Future Reality
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Biodiveristy is extremely important
Reserves must be set up Human population is expanding rapidle, demanding more food, land fro housing, higher standards of living Fossil fuels are runnign out (perhaps a good thing): Oil reserves gone in ~ 30 years, more pressure on agricultural land for fuel |
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Ensure Future (1)
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Stablize human population
o Population age structure studies can identify countries facing future over population problemsStop burning fossil fuels Alternative renewable energy (wind, solar, geothermal, biofuels) o Biofuels compete with food crops, aren’t energy efficient, and cayuse deforestation and soil erosion |
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Ensure Future (2)
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Stabilize air and water pollution
o Will be much easier when we stop burning fossil fuels o Phase out artificial fertilizers o Clean up industrial processes (ex. paper mills) o Recycling programs Establish conservation areas o Migratory species geographic location (often in different countries) involved (ex. monarch butterfly between US and SA, compounded because its food sources is one of the worst agricultural weeds in US, ragweed) o Costa Rica employing zoned reserve concept: Protected areas surrounded by zones compatible with both human activity and preservation of protected areas |
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Ensure Future (3)
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Sustainable tree harvest
o Management and expansion of remaining forests o Replanting trees o Reduce need for wood products (paper, buildings) o Paper recycling o Organizations (such as SHI) working worldwide to educate people in sustainable land-use practices o Drink only shade-grown coffee Increased food production/improved growing practices |
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Food Production/Improved Growing Practices
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Mulitcropping
Integrated pest management Limt use of artificial fertilizers and herbicides Efficient food distribution systems Genetic engineering of crop plants |
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Multi-cropping
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Crop rotation; different crops planted in alternate years
Inter cropping: rows of different crop plants alternate in same field at same time Slows spread of pathogens and herbivores that are attracted to a single crop Plants the repel herbivores (ex. marigolds) can be intercropped |
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Integrated Pest Management
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Plant only resistant varieties
Mulit-cropping Biological control agents (ex. ladybugs eat aphids) |
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Artificial Fertilizers & Herbicides
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Limit use
Reduce run-off of excess N into waterways Reduce biomagnification of toxins |
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Efficient Food Distribution Systems
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Buy locally-grown foods
Reduces fuel consumption Local food is fresher Less packaging waste Supports local economy |
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Genetic Engineering of Crop Plants
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Biotechnology has the potential to provide some solutions to impending food shortages
Plants can be engineered to be o Drought resistant o Pest resistant o Faster growing o More nutritious o Weirder |
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How To Make GMO's
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Insert a gen from one organism into the DNA of a different organism
o Result: a transgenic organism o Recombant DNA: DNA that has been spliced together from different sources |
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GM vs. GMO
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We have been genetically modifying plants for >10,000 years
o Began with beginning of agriculture o Unconscious selection of traits (ex. non-fracturing seed heads) o Increased with re-discovery of Mendel’s work (early 1900’s) All crop plants have been drastically genetically modified relative to wild ancestors Traditional plant breeding o Crossing one plant species with another plant species over multiple generations Modern plant breeding o Insert genes from different organisms into plants (animal, bacterial, and synthetic genes) Transgenic organisms is a better term than GMO |
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Proliferation of Transgenic Crops
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Commercial adoption of transgenic crops
o One of the most rapid cases of technology transfer in history of agriculture o ’96-’99: transgenic crop area increase from 1.7 to 39.9 mil hectares, now 114 mil (57.7 in US, mostly soy maize, cotton, potatoes) globally Anytime you eat, you are probably eating a transgenic food product |
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Debate Against Biotech
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Concerns about known and unknown risk regarding release of transgenic organisms into the environment
o Much animosity is political, economic, or ethical, but also biological Fundamental debate center on extent to which transgenic organisms could potentially harm human health or the environment |
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Debate For Biotech
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Increasing global population needs to increase world food supple
Need for sustainable energy Global warming Conserving the natural environment Protecting way of life of rural communities Biotech could help with many of these issues, but research and safety are necessary |
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Pros of Trangenic Plants
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Improve efficiency and effectiveness of agriculture
Decreased chemical application in agriculture Renewable energy and material sources Post harvest factors Bioremediation Pharmaceutical production |
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Arguments For Transgenic Plants: Efficiency & Effectiveness of Agriculture
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Productivity: more food from less land
• Increased yields • Modify plants to store as much food as possible • Improve tolerance to environmental conditions (drought, salinity, frost) Improve nutritional quality • Make amino acid composition of seeds more appropriate for human/mammalian nutrition • Combine the nutrients of grains and legumes into a single plant Manipulating vitamin content • Vitamin A deficiency affects 200 million people • Golden Rice may be solution o Milled rice has no beta-carotene o Humans use beta-carotene to make vitamin A o Daffodil genes that produce beta-carotene are inserted into rice DNA; not yet available for human consumption |
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Arguments For Trangenic Plants: Chemical Application in Agriculture
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Fertilizers
• Engineer plant species to convert atmospheric N to a form usable by plants • Reduce need for application of N fertilizers • Reduce nitrate run-off Pesticides • Transfer natural disease resistance from one species to another • Pease on left engineered to make an insect-resistant protein • No need to apply pesticides Herbicides • Crop plants can be engineered to tolerate glyphosate, a herbicide used against weeds among crops Both would considerably help reduce pollution of aquatic ecosystems Transgenic papaya (HI, ’98) resistant to ringspot virus saved papaya industry |
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Arguments For Trangenic Plants: Renewable Energy & Material Sources
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Biodiesel
• Modifying seed oil s they can be used to make diesel fuel Plastics precursors • Seed oils have been altered to make precursors for biodegradable plastics Fast-maturing trees • Wood is still used widely as fuel in many countries • New rapidly-growing reduce deforestation |
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Arguments For Trangenic Plants: Post-Harvest Factors
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Removing harmful compounds
• Paper production, lignin has to be dissolved using toxic chemicals • Trees can be engineered to have less lignin, reduces industrial waste and pollution Reducing spoilage waste and packaging • Modifying fruit ripening • Ex. Flavr Savr tomatoes modified not to rot after harvest, not currently on the market |
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Arguments For Trangenic Plants: Decontamination of Polluted Land
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Bacteria engineered to break down pollutants
• Ex. break down crude oil spills Many tyoes of contamination cannot be broken down • Ex. heavy metal pollution caused by mining and industry Trees engineered with heavy metal ion transporter (from bacteria) can be grown on contaminated land • Plants take up the heavy metal pollutants from the soil • Plants eventually removed along with the metals Disposed of safely; Ex. poplars with mercury transporters |
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Arguments For Transgenic Plants: Pharmaceutical Production
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“Biopharming”
• Insulin produced by genetically engineered bacteria since ’82 • As of 2005, 254 biopharmed drugs had been approved by US FDA • Hundreds of biopharm drugs currently in clinical trials Edible vaccines • Potatoes, tomatoes, bananas, being engineered to produce antibodies against pathogens • Administered to patients by ingestion • Eliminates need for refridgeration and semi-skilled personnel, expense of syringes • Make vaccination in developing countries more feasible • Still undergoing trials |
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Argument Against Transgenic Plants: Escaping Genes
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Plants interbreed much more freely than animals
Transgenic crop plants could potentially interbreed with wild/native population Genes from transgenic pharmaceutical plants could transfer to food crops Genes for herbicide resistance could transfer to weeds, potential creation of "superweeds" Ex. trans papaya to conventional papaya in HI; herbicide-resistance gene passed from crop to wild mustard plant in GB |
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Argument Against Transgenic Plants: Transfer of Antibiotic Resistance
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A gene is inserted into plants along with gene that make them resistant to an antibiotic
The antibiotic resistance gene serves as "marker" to indicate successful gene transfer Antibiotic resistance genes could escape to other organisms, possibly result in bacteria that are resistant to antibiotics This approach is being replaced with different kinds of marker genes |
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Argument Against Transgenic Plants: Transfer of Allergenic Genes
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’96 a transgenic soybean was developed
Protein content was improved by inserting a gene from the Brazil nut Intended to be used only as animal feed Lab tests showed the soybean variety could cause allergic reactions in humans allergic to Brazil nuts Development of soybean was discontinued before product reached the market |
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Argument Against Transgenic Plants: Impacts on Birds, Insects, Soil Organisms
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Concerns that growing transgenic crops might have harmful effects on non-target organisms
When a plant is genetically modified, so is its pollen Effects of altered proteins from transgenic pollen are largely unknown But which is worse for beneficial insects • Chemical insecticides or transgenic plants |
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Argument Against Transgenic Plants: Mixing Transgenic Products in Food Chain
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Transgenic corn (Starlink) intended for animal feed was accidentally used in food for human consumption (corn meal, Taco Bell taco shells)
The transgenic corn was not found to be dangerous to humans Fear is that some people might develop allergy to protein in the transgenic corn Highlights need for rigorous testing and controls |
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Argument Against Transgenic Plants: Loss of Farmers' Access to Plant Material
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Biotech research is done mostly by private sector
Larch biotech firms (ex. Monsanto, calgene) hold patents on transgenic plants Concerns about market dominance by just a few companies Farmer not allowed to save seeds for next season • Argentina is 2nd biggest grower of transgenic crops • They ignore Monstanto’s patent on Roundup Ready soy • Save seeds from year to year, buy/sell seed on the black market |
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Argument Against Transgenic Plants: Long-Term Consequences Unknown
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No long-term studies, because technology is so new
Questions • How long will the transgene continue to function? • What happens when the transgene mutates • Could insertion of artifical/foreign genes destabilize organisms after multiple generations? • Long-term consequences of consuming foods that manufacture pesticides and herbicides? • Humans evolved over millions of years by adapting gradually to environment. What are the consequences of rapidly transforming our food? |
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Cons of Transgenic Plants
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Genes can “escape”, end up in unwanted places
Transfer of antibiotic resistance Transfer of allergenic genes Impact on birds, insects, soil organisms Mixing of transgenic products in food chain Loss of farmers’ access to plant material Long term consequences are unknown |
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Solutions to Transgenic Plant Problems
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Rigorous scientific testing
• Scientists and the public need to assess the possible benefits of transgenic products vs. risk on a case-by-case basis • Decisions need to be based on sound scientific data rather than reflexive fear Regulations against mixing transgenic foods with non-transgenic foods, traceability, GMO test strips Clear labeling of foods made from products of transgenic organisms • Give consumers a choice • Reduce potential for allergic reactions • Require in E.U. and Asia; U.S. and Canada resistant Biotech advocates argue that similar demands were not raised when GMcrops were produced by traditional plant breeding techniques • “Conventional breeders can bombard plant cells with chemicals and radiation to create useful mutants without having to check how it affects their DNA” Overhaul of regulatory system, including conventional plant breeding practices, is necessary |