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Environmental Biology 09/10/2013
Tragedy of the Commons
Theory why humans are doomed
“Commons”-a public item for personal use
Ex: public pasture, 10 people graze their cattle
1 person adds, cattle, everyone else has to pay b/c can’t graze as much, and only one person benefits
Everyone starts to add cattle, becomes overgrazed
Then everyone loses
Shared resources will be exploited and ruined because of human greed
“Common” Resources
Water (oceans), forest, petroleum
Can they be owned?
Disagreements over what is common
Countries always want control
More people=more pressure on resources, pollution
World pop.=Over 7.1 billion
Easter Island
Random island
When they found it, 3000 people, small animals, poor soil
800 stone statues
Island used to be very prosperous, plentiful food, thick jungles, many trees
At first, 7000 people, relaxed lifestyle
By 1400, no trees
Trees are needed in hydrologic cycle
Precipitation, infiltration, runoff, evapotranspiration, condensation
Lose the trees, lose soil, plants, animals, crops, rain barely comes
Loss of resources=lower quality of life
Positive feedback cycle
Things are getting baduse more to compensate
Fewer resourcesincreased competitionleads to positive feedback
Other examples: Nazca people in Peru
Irrevocable Problems
Many can be avoided
Can be on the road to extinction, but then thrive
3 Keys to avoid Environmental Problems
Key 1: Recognizing Problems
Understand your world
Where are the problems and the solutions
Key 2: Education and Communication
Develop and enact management
Develop common goods
Key 3: Action and Responsibility
If you find a solution, do it!
Individuals CAN make a difference
7.1 billion x anything is a lot, can make something happen
EX: DDT-insecticide, extremely helpful
Used during WWII to prevent disease
However, beneficial invertebrates began disappearing, thinner egg shells
Discovered by Rachel Carson
DDT was banned and wildlife recovered
Still used for malaria

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Environmental Biology 09/10/2013 Tragedy of the Commons Theory why humans are doomed “Commons”­a public item for personal use Ex: public pasture, 10 people graze their cattle 1 person adds, cattle, everyone else has to pay b/c can’t graze as much, and only one person benefits Everyone starts to add cattle, becomes overgrazed Then everyone loses Shared resources will be exploited and ruined because of human greed “Common” Resources Water (oceans), forest, petroleum Can they be owned? Disagreements over what is common Countries always want control Overpopulation More people=more pressure on resources, pollution World pop.=Over 7.1 billion Easter Island Random island When they found it, 3000 people, small animals, poor soil 800 stone statues Island used to be very prosperous, plentiful food, thick jungles, many trees At first, 7000 people, relaxed lifestyle By 1400, no trees Trees are needed in hydrologic cycle Precipitation, infiltration, runoff, evapotranspiration, condensation Lose the trees, lose soil, plants, animals, crops, rain barely comes Loss of resources=lower quality of life Positive feedback cycle Things are getting bad▯use more to compensate Fewer resources▯increased competition▯leads to positive feedback Other examples: Nazca people in Peru Irrevocable Problems Extinction Many can be avoided Can be on the road to extinction, but then thrive 3 Keys to avoid Environmental Problems Key 1: Recognizing Problems Understand your world Where are the problems and the solutions Key 2: Education and Communication Develop and enact management Develop common goods Key 3: Action and Responsibility If you find a solution, do it! Individuals CAN make a difference 7.1 billion x anything is a lot, can make something happen EX: DDT­insecticide, extremely helpful Used during WWII to prevent disease However, beneficial invertebrates began disappearing, thinner egg shells Discovered by Rachel Carson DDT was banned and wildlife recovered Still used for malaria 09/10/2013 Big Game Could Roam U.S. Plains Wanted to bring many big animals to Great Plains Ecosystem there is mostly gone Used to have millions of big game Fewer bison and prairie animals Replaced by cattle, deer and coyotes Many empty niches▯add more species w/ little problems Niche: what a species does for a living; how, where and when 2 species cannot have the same niche in the same location Pleistocene Re­Wilding Project Wanted to bring big animals from Africa to the Great Plains Assertions Help endangered African animals Help create jobs Bad because exotic species sometimes destroys natural species Is the threat still there? Were taken out once, could it happen again? Change of habitat Keep them in Native habitat in Africa Ecosystem could collapse 09/10/2013 Approaches to Biodiversity Conservation Species focus US▯ Endangered Species Act Ecosystem focus 2010: International Year of Biodiversity The plants, animals, microorganisms and ecosystems that they create Includes species, genetic variability, population structure 1. Species Number and different types of species Source of raw materials Goal of conservation biology isn’t to maximize biodiversity Goal is to maximize native species 1.5 million species described 86% of all species on land 91% in seas have yet to be discovered Discovering New species Access to new places Need experts to ID species Taxonomy=important to discover species 09/10/2013 Current problems 20% of bird species have gone extinct in 2000 years IUCN­tracks extinction, has red list of endangered species 1/8 of birds, ¼ of mammals, 1/3 of amphibians Hawaiian Birds, after human colonization many species were wiped out Many natural species are dying out through diseases 2. Genetic Variability Allows species to evolve and adapt to changing conditions Basis for crop development, important for humans Raw materials for transgenic changes 3. Population structure Connections across a species’ range 4. Species Composition How it changes across space and time 5. Interactions Among Species Predator­Prey Symbioses Competition 6. Abiotic Environment Processes that support the biotic community Nutrients, water 09/10/2013 Elevation Can limit species distribution and abundance Ecological “Services” Biological, physical, and chemical processes in ecosystems Benefit humans Rapidly growing fields in biology and economics What are the costs? Maintain air quality Regulate climate: local and regional rainfall Flood Control/Prevention 7. Biological “Phenomena” Migrations Large aggregations of animals Fall colors Does species diversity matter? Some people care intrinsically Yes! Promotes human health Food and Drug Production Healthy ecosystems resist trauma Ex: Prairie grassland plants More species diversity= more primary productivity Effect diminishes fast after around 6 species Decreases disease risk “Dilution effect”­species dilute the impact of diseases IT ALL DEPENDS But more, yes 09/10/2013 What is an Ecosystem? 09/10/2013 Conceptual model Model=simplified representation of the real world Context for analyzing Group of organisms, physical environment and biotic and abiotic interactions and processes Arbitrary boundaries An “outside” that affects it Ecosystems are hierarchical Every ecosystem is a part of a bigger ecosystem Space and time scales depends on species or processes of interest Community=living part of ecosystem 90% of energy is lost at each level of trophic pyramid Cannot have more mass of consumer than consumed Base of Community: Primary Production Plant growth and reproduction Determines available energy Affects number of species, individuals, community complexity Gross Primary Productivity Net Primary Productivity GPP­ Cost of acquisition and storage Limits carrying capacity 09/10/2013 Max number of individuals that can be sustained 59% on land, 41% in ocean Humans use around 27% of earth’s NPP Food Web Many more species in the web More interactions than displayed Some species change roles as they age Even though extremely complicated, still less than real world Understanding Species Interactions Community Structure Predicting consequences of management Interactions Predation Competition Symbiotic, 3 different types When 2 species interact, and 1 or both depends completely on each other Not predator­prey Parasitic 09/10/2013 One benefits, the other is affected negatively Tick, tapeworm Commensal One benefits, the other has no change Mutualistic Both species benefit Semi­Myth Ecosystems and Endangered Species are fragile NOT TRUE Some are fragile; cryptobiotic soils In some ecosystems, when species disappear there are no changes Not all species are equal in an ecosystem Keystone Species Species whose effect is disproportionally large to the effect other species have 1. Alter structure of the environment ex: beavers and woodpeckers 2. Drive energy flow of community Key role in food webs Top predator Provide food for species during critical times Ex: exotic species invasion Goes from keystone than dominant Displace or eat native Break down dead stuff Seed dispersal Science 09/10/2013 Science Science 09/10/2013 Concepts, misconceptions What is it? How is it done? Science—Public Interface Important to environmental efforts Science should be made accessible Used and misused by environmentalists and non­environmentalists Are decisions based on good science? What else matters? Scientists often wonder Goals of Science Discovery Propose, test and revise ideas about how the natural world works Science tries to identify patterns and generate explanations for patterns and phenomena How do we assess problems?  Scientific Method Make observations Ex: Amphibians disappearing from sites all over the globe Some anecdotal data Science 09/10/2013 Some systematic surveys Disappearing mostly in Western hemisphere Make a hypothesis How you think it works Habitat loss Climate change Environmental contamination Select one or more to test; make predictions—observational, experimental  Do experiments, collect data Experiments are conducted at natural oviposition sites in the exact spot where eggs are laid Conclusion? UV­B radiation may cause damage New questions may arise If hypothesis isn’t supported, make a new one and restart process Hypothesis can become theory=accepted by the scientific community as correct Hypothesis can become scientific law=appears to be invariable in nature, uncommon in biology One Key to Science Hypotheses, theories, and laws can be rejected by new data If you can’t reject the idea based on data you can gather, it is NOT science Glossary Deductive Reasoning Science 09/10/2013 Repeated observations lead to hypothesis of pattern Science usually presented as deductive Inductive Reasoning Formulation of universal statement from singular observation Ex: this plant makes food from sunlight; all plants do this Primary Means of Scientific Progress Observations Discovery, looking for patterns Models Simplifications of the real world Mental, schematic, mathematical Why use models? Organize your thoughts ID what you don’t know, need to gather data Can make inferences about the real world without actually altering it Might not be able to do experiments you want in the real world EX: Life Cycle Assessment=a model Trying to estimate true costs Input­output model Becoming THE way to analyze environmental science Science 09/10/2013 Experiments Observation: trees grow from the ground Hypothesis: trees derive the materials for growth from the soil Prediction: if hypothesis is true, soil should lose mass as tree grows Experiment: Cut 5 lbs of willow tree and got 200 lbs of soil Plant branch in soil in a bucket Result Plant was 164 lbs, soil was 199 lbs Conclusion Reject hypothesis Not Science California coast, 1899 Fisheries very important Observation Catch was below what was expected Hypothesis Sea lions were eating their salmon Experiment None Conclusion Science 09/10/2013 Sea lions eating all salmon Result Killed many sea lions Conflict of Interest in Science? Colony Collapse Disorder Honey bees are worth 14 billion in US economy Observations Low number of adult bees in hive No bodies No outward sign of disease Predictions Pesitcides Solution Life Cycle Assessment Paper vs Plastic 09/10/2013 Why? Hypotheses H1: Great enough that cat relaxed and impact less sever on a relaxed cat H2: Great enough that cat able to position itself during fall to maximize wind resistance, thus less fall  rate=lessen impact Real Answer=Biased Data In fact—the greater the height of fall, the greater the probability of death Source of data=vet clinics=biased data Income of Tufts Graduates Assertion: Average income of 2005 grads in $487,346/year Clues/Questions Figure is too precise Not many people know their income to 6 digits People often exaggerate their incomes when asked; ego? Who was included? Whose address might be more difficult to find—a rich person or a poor person? Homeless? Who is more likely to respond to the questionnaire; rich or poor? In Statistics Try to imagine how they got the data and whether you trust the data 09/10/2013 Three Types of Average Mean=Arithmetic Average Median=Middle Value Mode=Most Common Value Deception Using Listerine reduces cavities 30% over brushing alone In laboratory tests, this product kills bacteria that cause illness! Spurious Correlations (cause and effect) Mixing cause and effect People who have annual check­ups probably live healthier lives and take better care of their bodies Correlation doesn’t equal cause and effect Extrapolation Beyond the Data The more it rains the higher the corn grows=cause and effect Lie Factor Sixe of effect shown in graphic/actual size 09/10/2013 Mass Extinction Then and Now 1. Patterns Then: genera; sub­continental scale Now: Worldwide, species/subspecies level Selective; ex habitat specialists Certain species at risk b/c of humans 2. Causes Then: nature Now: humans Current Problems In jeopardy Amphibians species: IUCN risk categories They keep in track species doing well, but those that aren’t doing well Difference between island and continental species Island species have nowhere to go, continental species have somewhere Why don’t people care? With time and science, it will get better Why do we care about species extinction? 09/10/2013 Main threats Habitat loss and degradation #1 threat to global biodiversity Alien species Pollution More plants are going extinct than birds Threat Habitat loss Straightforward concept Without habitat, there is no wildlife Habitat=area that provides some requirement for a species Breeding site, food, migration corridor Fragmentation Habitats are spread apart, no movement When a species requires more than one habitat type, it is vulnerable to losses in any of the types Bachman’s warbler Likely extinct, due to deforestation on its wintering grounds Risk to Monarchs Habitat loss on wintering grounds Habitat Loss: Agriculture 09/10/2013 More than 30% of Earth’s and is farmland Habitat Degradation: Overgrazing Loss of plant species Loss of associated animal species Disturbance allows exotic plant invasion Soil compaction Lowers the water table Further impacts plant community Stream bank erosion Effects of Grazing Great Basin Arid/desert Did not evolve with grazing Significant negative effects Over­exploitation Primarily a threat when the target species have Low reproductive rates Small range Habitat specialization Biologically: deaths>reproduction Over­Harvest, Steller’s Sea Cow 09/10/2013 Marine mammal, northern Pacific 10 tons No fear of humans=easy to kills Hunted intensively Extinct 27 years after discovery Wide variety of species are exploited Frankincense Study in Eritrea, where it is harvested Harvested by wounding every 3 weeks Effect of harvest on trees? Very little tree recruitment Cascading Effects Red knot migration coincides with horseshoe crab breeding Has worked for 350 million years Threats to Horshoe Crab Used as bait Used for medical purposes Horseshoe crab harvest leads to red knot decrease San Joaquin Valley Soil naturally high 
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