ENSP 200 Exam 1 9/28/14 3:29 PMEnvironmental Ethics, Economics, and Policy

2.1 Changing Views of Humans and NaturePre-Industrial Views

Our view of our relationship to nature changed as our dependence on it became less immediate and obvious

Animism: the belief that living and nonliving objects possess a spirit or a soul

Many Native American traditions assign sacred status to Mother Earth and Father Sky, whose union they assert produced all life

The Enlightenment and Industrial Revolution New knowledge and ever-growing human impacts on the

environment catalyzed new views of the relationship of man and nature

New technology, science understanding (evolution), ideas (modern environmental movement)

Voltaire (1694-1778) openly questioned humanity’s special relationship to God

Jean-Baptiste Lamarck proposed that the human species was simply one of many products of a process of evolution (1809).

o Didn’t get much acceptance Charles Darwin’s theory of evolution by means of natural selection

provided a clear explanation for evolutionary change (1859) Ralph Waldo Emerson published his short book Nature where he

argued that the obsession of industrial societies with material goods broke the connection between humans and nature (1836)

o Known as the origin of the American transcendental movement

Transcendental movement: Nathaniel Hawthorne, Walt Whitman, Hendry David Thoreau

o Thoreau’s Walden is the most enduring of all transcendentalist writings

George Perkins Marsh’s book Man and Nature is viewed by many as the genesis of the modern environmental movement.

o Argued that nature is essentially “harmonious” but humans have separated themselves from nature and thereby violated its harmonies to the detriment of both nature and humans

o Argued that our survival requires that we reconcile our activities with the inescapable laws of the natural world

Conservation vs. Preservation Preservationist: the view that parks and public lands should

preserve wild nature in its pristine state, and that humans should have access to wilderness parks for their inspiration and beauty, but that parks should be protected from consumptive uses such as logging or water diversion

o The Sierra Club: one of the earliest nongovernmental environmental advocacy organizations. Founded by John Muir

o Preservationists argued that nature had value in its own right and therefore deserved protection

Conservationist: the view that public resources should be used and managed in a sustainable fashion to provide the greatest benefit to the greatest number of people.

o Conservationists valued nature for the goods and services it provided human beings

The Modern Era Environmental trends, debates, and warnings dominate media Begging to understand dependence on environment Aldo Leopold argued for both the sustainable human use of natural

resources and the preservation of wildernesso Thought that wilderness provides resources that are essential

to civilizationo Warned that human impacts on ecosystems differ significantly

from natural disturbances Rachel Carson wrote Silent Spring in which she pointed out the

danger that pesticides posed to natural ecosystems and to humans (1962)

o After World War II the widespread use of the pesticide DDT wiped out disease-carrying mosquitos as well as the birds that fed on them and their predators

Paul Ehrlich’s book The Population Bomb told the public how the rapid growth of the human population was threatening the environment and human survival (1968)

2.2 Environmental Ethics Environmental Ethics: studies the moral relationship of humans to

the environment and its nonhuman contentsDoing the Right Thing

Plato , a Greek philosopher, proposed that motivation should be the basis for determining whether an action was good

Virtue Ethics: Plato’s system in which an action is right if it is motivated by virtues, such as kindness, honesty, loyalty, and justice

Consequence-based Ethics: emphasizes the importance of outcomes. An action is right depending on whether or not it delivers pleasure, benefit, or satisfaction.

o Utilitarianism: defines right actions as those that deliver the greatest good to the greatest number

Immanuel Kant , 18th century philosopher, advocated duty-based ethics

o Duty-based Ethics: the rightness or wrongness of actions should be determined by a set of rules or laws

o A wrong action is wrong regardless of its outcomeWho or What Matters?

Intrinsic Value: a person, organism, or object valued as an end unto itself is said to have intrinsic value

o Most ethicists agree that every human has intrinsic value Instrumental Value: a thing that is valued as a means to some other

end has instrumental valueo Some ethicists argue that other living things have value only

as a means to support the well-being of humans Anthropocentric Ethics: assigns intrinsic value only to humans; it

defines right actions in terms of outcomes for human beingso Places of beauty (Yosemite) and charismatic animals (panda

bears) acquire instrumental value because humans care about them

Biocentric Ethics: argues that the value of other living things is equal to the value of humans

o Extends intrinsic value to individual organisms beyond human beings; the organisms do not need to benefit humans in order to have value

o Two distinct schools1. Some argue that for a thing to have intrinsic value it

must be ale to experience pleasure or satisfaction. Therefore, it must possess qualities such as self-perception, desires, memory, and a sense of future.

2. Some argue that any individual organism that is the product of natural evolution has intrinsic value

o Hunting is unethical because it violates the intrinsic value of the individual organism

Ecocentric Ethics: places value on communities of organisms and ecosystems

o Believes that collections of organisms or critical features in the environment have intrinsic value

o Might argue that because hunting individual animals improves the health of that species’ populations by removing diseased animals, it is a right action

o Andrew Brennan argues that a natural entity such as a river has intrinsic value and is not a “mere instrument.”

o Deep Ecology Movement: nature deserves moral respect in its own right. Because we are the air we breathe, the water we drink, and the food we eat, all elements of the environment have equal intrinsic value

o

Intrinsic Value

Instrumental Value

Hunting

Anthropocentric

Only to humans

Everything that helps humans

Biocentric All living things

Hunting is unethical

Ecocentric Communities and Ecosystems

Hunting removes diseased animals

Ecofeminism and Environmental Justice Françoise d'Eaubonne argued ecofeminism in her book Le

Feminisme ou la Morte (Feminism or Death) (1974) Ecofeminism: argues that exploitation and abuse of both the

environment and women derive from male domination Women suffer disproportionately from human destruction of the

environment Environmental Justice Movement: seeks to ensure that in the

management of natural resources an the environment people are treated fairly regardless of race, gender, or economic status

o The placement of waste facilities has been a consequence of direct racial discrimination. In other cases, sites have been selected because land near poor communities is cheap

o In either situation, poor communities must bear a large share of the costs and risks associated with such facilities

2.6 U.S. Environmental Law and PolicyGovernment Functions

The three branches of the federal government and state and local governments play unique roles in setting environmental policy

1. Legislative Branch - The Congressa. Consists of House of Representatives and Senateb. Legislation is either approved or vetoed by the president.

Congress may override a presidential veto by a two-thirds majority of both houses

2. Executive Branch - The Presidenta. Responsible for the implementation and enforcement of

legislation b. Headed by president and includes the cabinet and many

departments and agenciesc. Enforcement of particular legislation is generally assigned to

one or few agenciesd. Regulations: specific rules that establish standards for

performance, programs to ensure compliance, and protocols for enforcement. These are set by agencies

3. Judicial Branch – The Courtsa. Responsible for continued re-interpretation of the lawb. Includes the Supreme Court and the lower courtsc. Case Law: various decisions made by individual courts

The Constitution and Environmental Policy Several articles and amendments to the U.S. Constitution

significantly influence environmental policy

2.7 International Environmental Law and PolicyEnvironmental Laws

Sovereignty: the concept that a country may behave as it pleases within its borders as long as it does not violate international laws to which it has agreed. These laws may be in 1 of 3 forms

o Customary International Laws: accepted norms of behavior or rules that countries follow as a matter of long-standing precedent.

It is customary in international law that countries may not use their territory in such a way as to injure the territory of another country and that countries have a duty to warn other countries about environmental emergencies

o Conventional International Laws: established by formal, legally binding conventions or treaties among countries

The US and 17 other countries ratified the Convention on Nature Protection and Wildlife Preservation in the Western Hemisphere

o Judicial International Law: sets standards for the actions of countries based on the decisions of international courts and tribunals

International Court of Justice in The Hague, Netherlands is the most famous of these courts

Enforcement of international environmental law is somewhat limited1. It is often difficult to verify whether a particular country is

complying with the terms of a treaty2. Countries may enter into an agreement in good faith but lack

the capacity to enforce its terms

3. The international community has few options for punishing countries that violate a treaty

International Institutions The United Nations

o The most important organization shaping international environmental policy and law

o 54 member nations Regional Consortia

o Countries within different regions have formed organizations to encourage communication and cooperation on matters of particular interest

o Organization of American States represents 35 countries in the Western Hemisphere

o European Union (EU) created to promote European unity 27 member countries

International Financial Institutionso Multinational Development Banks: institutions that provide

financial and technical assistance to countries for economic, social and environmental development

o Largest is World Bank which provides long-term loans and grants to the poorest countries in the world

o Funded by donations from wealthier countrieso The World Trade Organization (WTO) was created in 1995 to

promote free trade by reducing obstacles to international commerce and enforcing fairness in trading practices

Nongovernmental Organizations (NGO’s)o Legally constituted organizations in which there is no

governmental participation or representationo Some (such as Greenpeace) advocate for national laws and

international treaties to protect the environment o Others (such as World Wildlife Fund) work with the

governments to develop the capacity to implement and enforce laws and treaties

9/28/14 3:29 PMThe Physical Science of the Environment

3.1 Chemistry of the Environment Elements: a chemical that cannot be broken down or separated into

other chemicals Atoms: an element’s most basic subunit Molecules: a chemical bond of two or more atoms (O2 or N2)

Atoms, the basic unit of matter There are 92 naturally occurring elements Protons: positively charged particles

o Number of protons in an element is called the atomic number (Z)

Neutrons: electrically neutral particles Mass number (A) is the number of protons plus neutrons Electrons: negatively charged particles The mass of each a proton and neutron is more than 1,000 times

greater than the mass of an electron Isotopes: atoms of an element with the same number of protons but

different numbers of neutrons Radioactive Isotopes: aka radioisotope, isotopes that have nuclei

that are unstable and can break apart, they spontaneously “decay,” emitting various combinations of high-energy protons, neutrons, electrons, and radiation

Half-life: the length of time that it takes for half of a collection of atoms of radioisotope to decay

Molecules and Ionic Compounds Compounds: molecules that are made of more than one element

(CO2 or H2O) Covalent bonds: strong bonds formed when atoms share electrons Ions: atom gained or lost an electron

o Cation = position, anion = negative Ionic bonds: bonds between metals and nonmetals

o Strong bonds formed when one atoms transfers one of its electrons to another atom

o Compounds formed by ionic bonds are not called molecules; instead they are called ionic compounds or salts

o Ionic compounds are held together by ionic bonds and exist in a crystal

Dipole bonds: weaker bonds that form between atoms and molecules as a consequence of shifts in electrical charge

Metals lose electrons to take on the electron structure of the previous noble gas. In doing so, they form positive ions (cations)

Nonmetals tend to lose electrons to take on the electron structure of the next noble gas. In doing so, they form negative ions (anions)

Covalent bonds are formed when molecules share electronso Can share 1, 2, or 3 pairs (single, double, or triple bond)

Electronegativity: measure of an atom’s attraction for the elements in a bond

The Water Molecule Solubility: the ability of a chemical to dissolve in a particular liquid The pH Scale: a quantitative representation of the relative amounts

of hydrogen and hydroxyl ions in a liquid

3.2 The Organic Chemistry of Life Organic Molecules: made of carbon atoms covalently bonded to

hydrogen and other atoms Inorganic: compounds that are not made up of carbon and hydrogen

Hydrocarbons and Carbohydrates Hydrocarbons: organic molecules composed entirely of carbon and

hydrogen atoms Carbohydrates: organic molecules made of carbon, hydrogen, and

oxygen

Sugars: carbohydrates with the general chemical formula (CH2O)n, where “n” is between 3 and 7.

Lipids: or fats and oils, organic molecules made of long chains of carbon and hydrogen atoms and a shorter region with one to several oxygen molecules

o Most are not soluble in water (water and oil/vinegar)Macromolecules

Macromolecules: a combination of small organic molecules linked together

Polymers: larger chains or networks where simple organic molecules link together

Polysaccharides: polymers of simple sugar moleculeso Starch and cellulose are polysaccharides composed of

hundreds of glucose molecules Proteins: polymers made of nitrogen-containing organic molecules

called amino acids Catalysts: substances that promote chemical reactions without

being consumed in the reactiono Proteins that serve as catalysts are called enzymes

Nucleic Acids: polymers of chemical subunits called nucleotides Deoxyribonucleic acid (DNA): forms the hereditary material that is

passed from generation to generation in all organisms Genes: carry the code used to synthesize, or build, specific proteins Genome: an organism’s complete set of DNA Ribonucleic acid (RNA): similar to the structure of DNA, except the

nucleotides of RNA contain the sugar ribose rather than deoxyribose and the nitrogenous base utracil (U) rather than thymine (T)

Proteins are synthesized in a two-step process1. Transcription: the DNA code for a particular gene is rewritten as

a segment of RNA2. Translation: the RNA in the first step then serves as the

template for the assembly of a specific protein

3.3 Energy and the Environment

Energy: the capacity to do workEnergy

Isaac Newton’s first law of motion states that any object at rest will stay at rest, and any object in motion will remain in motion unless acted upon by some force

Work: a force applied to an object over some distance Energy exists in two general forms

1. Potential Energy: the energy that is stored in a system and available to do work in the future

2. Kinetic Energy: the energy of motionLaws of Thermodynamics

First law of Thermodynamics: states that the total amount of energy in the universe is constant

o Also called the law of energy conservation Second law of Thermodynamics: states that every energy

transformation increases disorder Entropy: the disorder or disorganization in a system

o In every energy transformation, some amount of energy is converted to entropy

Heat: the random motion of moleculeso The least usable form of energy

Forms of Energy Four types of energy are especially important in ecosystems1. Electromagnetic radiation: the energy of light

i. This energy is transported at a remarkable speed as “particles” called photons, which have no mass and behave like waves

ii. The amounts of energy carried by the different forms of electromagnetic radiation are determined by their wavelength, the distance from one wave crest to the next

iii. Electromagnetic Spectrum: the full range of wavelengths

iv. Visible light1. Represents small portion of the total spectrum2. Different wavelengths form the various colors3. Photons are sufficiently energetic to elevate the energy

level of electrons in organic molecules without breaking their bonds

v. Gamma rays, X-rays, UV light1. Wavelengths shorter than visible light2. Photons pack energy sufficient to disrupt the bonds in

many organic molecules, thus, these forms of radiation are generally harmful to living systems

vi. Infrared radiation, microwaves, radio waves1. Carry less energy than visible light2. Photons carry sufficient energy to increase the kinetic

energy of molecules 3. Can break very weak chemical bonds

2. Heati. Refers to the kinetic energy of moleculesii. Temperature: a measure of the average kinetic energy of a

collection of moleculesiii. Daniel Gabriel Fahrenheit proposed a temperature scale in

which water freezes at 32° and boils at 212° (1727)iv. Anders Celsius proposed a temperature scale that set 0° as the

freezing point and 100° as the boiling point of water (1742)v. Heat can move in four ways

1. Conduction: direct transfer of heat by means of the collisions of molecules

2. Convection: circulation due to differences in densitya. Occurs because warm regions in a gas or liquid

become less dense and rise, causing the gas or liquid to circulate

3. Radiation: the release of electromagnetic energy

a. Wavelength of the radiation that is given off decreases with increasing temperature

4. Latent Heat Transfer: results from evaporation of more energetic molecules

a. Occurs as the molecules with the highest kinetic energy evaporate, leaving behind molecules with lower kinetic energy and temperature

b. When you sweat and your perspiration evaporates, cooling your skin

3. Chemical energy: the potential energy associated with the formation or breakage of bonds between atoms

i. Photosynthesis – green plants use light energy to assemble carbohydrates from carbon dioxide and water

4. Nuclear energy: the energy contained in the structure of matter itself

i. The transformation of mass to energy occurs as a consequence of two processes

1. Nuclear Fission: occurs when the nucleus of an atom is split, producing two or more smaller nuclei and a great deal of electromagnetic and kinetic energy

a. Changes one element into one or more other elements

2. Nuclear Fusion: occurs when two atoms collide with so much energy that their nuclei fuse, forming an atom of a new element

a. Process that powers the sunEnergy Units

Joule (J): the energy required to support a 1-kg mass against the force of gravity

o Fundamental unit of energy is named in honor of a 19th century scientist, James Prescott Joule

Calorie (cal): the energy required to raise the temperature of 1-g of water by 1° C (1 cal = 4.18 J)

Watt-hour (Wh): the energy expended over an hour at the rate of 1 joule per second

3.5 Earth’s StructureThe Core, Mantle, and Crust1. The Core: layer at the center of Earth

a. Composed of a mixture of nickel and ironb. Has two parts: solid inner core, and a liquid outer corec. Convection currents and Earth’s rotation stir the molten iron of the

liquid outer core, setting up a strong magnetic field which orients the magnetic needed of a compass

2. The Mantle: second layer of dense rocka. Occupies 70% of Earth’s total volumeb. In parts of the upper mantle, rocks may be heated to a liquid-like

state called magmac. Rich in elements magnesium and silicon

3. The Crust: a thin layer of solid and relatively light rocksa. Makes up less than 1% of Earth’s total volumeb. Continental crust makes up the continents and the areas

immediately adjacent to themc. Ocean crust, which lies beneath most of the deep ocean, is

composed of denser and more homogeneous rocks that are similar to the rocks in the mantle

d. Lithosphere: the crust and the upper reaches of the mantle that interact with it

i. Zone of geologic activity that has shaped Earth’s surface and continues to do so

e. Hydrosphere: composed of the liquid water and ice in and on the crust and includes oceans, rivers, and glaciers

Building and Moving Continents Scientists have observed that the margins of some continents

match up with those of other continents In the 19th and early 20th centuries geologists observed that

sedimentary rocks on separate continents often hold the same kinds of fossils

In 1911, the German scientist Alfred Wegener said that in the distant past all of the continents were joined as one large continent: Pangea

It was observed that the ages of rocks in the crust vary greatly

Tectonic Plates: pieces of the crust that float on top of the mantle Places where plates come together are called boundaries; the type

of boundary depends upon how the plates are moving in relation to one another

Transform Fault Boundaries: plates slide past one anothero May generate earthquakes

Divergent Boundaries: plates that are moving aparto Coincide with ocean ridges, creates ocean crusto Hot magma from the mantle rises to the surface, forming new

ocean crust Convergent Boundaries: plates collide

o Subduction: ocean and continental plates meet, the dense ocean crust is thrust beneath the lighter continental crust

o May cause earthquakes or volcanoeso Collision of two continental crust plates causes the land along

the boundary to thrust upward, producing mountains. This caused the Himalayas between India and Asia

3.6 Earth’s Atmosphere Atmosphere: the layers of gases above a surface

Composition of Gases Earth’s atmosphere is rich in nitrogen (78%) and oxygen (21%), the

clouds indicate lots of water vapor The Martian atmosphere is nearly 97% carbon dioxide with virtually

no water vaporLayers of the Atmosphere

Atmospheric Pressure: the force caused by the pull of gravity on a column of air. Diminishes with increasing altitude

Four layers of the atmosphere1. Troposphere: lowest layer

i. Provides the air that we breatheii. Most weather occurs in this layer

2. Stratospherei. Temperature gradually increases moving upii. Upper boundary is the stratopauseiii. Ozone Layer: layer of stratosphere where there are

large amounts of oxygen in the form of ozone (O3)iv. Ozone layer is effective in absorbing and scattering the

abundant UV light - providing great protection3. Mesosphere

i. Air temperature begins to drop4. Thermosphere

i. Density of gas is very lowii. Gases in this layer are heated by direct solar radiation

to very hot temperaturesiii. Many gases in this layer are ions, which have electrical

charge. These ions interact with the solar wind and Earth’s magnetic field to produce auroras

iv. International Space Station orbits herev. Auroras occur here

Water in the Atmosphere Vapor Pressure: water’s relative contribution to total atmospheric

pressure Saturation Vapor Pressure: the amount of water the air can hold Relative Humidity: a measure of the extent to which air is saturated,

expressed as a percentage Dew point: the temperature at which the relative humidity is 100% Amount of water air can hold raises with temperature

3.7 Earth’s Energy Budget, Weather, and Climate

Earth’s Energy Budget Energy Budget: a system of accounting the measures of all the

energy entering and leaving Earth Over the course of a year, the energy budget of the entire Earth is

balanced – the total amount of energy coming in is equal to the total energy that is reflected or radiated back into space

Weather and Climate Climate: atmospheric conditions such as temperature, humidity,

and rainfall that exist over large regions and relatively long period of time

Weather: short-term variations in local atmospheric conditionsWind Cells

Intertropical Convergence Zone: a band of rising air around the equator

Hadley Cells: convention cells on either side of the equatoro Formed by the air diverging northward or southward

Ferrel Cells/Polar Cells: convection cells in each hemisphere at latitudes between 30 and 60 degrees and 60 and 90 degrees

Coriolis Effect: the apparent change in wind direction due to Earth’s rotation

The Seasons Seasons occur because Earth is tilted on its axis by 23.5 degrees.

Each hemisphere is tilted toward the sun during its summer and away during winter

9/28/14 3:29 PMOrganism and Population Ecology and Evolution

4.1 The Cell – The Fundamental Unit of LifeCell Structure

Biologists use cell structure to classify organisms into one or two groups: prokaryotes and eukaryotes.

Both groups have cells that are made up of a material called cytoplasm

Around the cytoplasm is a plasma membrane that regulates materials flowing in and out of the cell

Prokaryotes: cells that lack organelleso Simple compared to eukaryoteso Lack membrane-enclosed nucleuso Their DNA occurs as a single chromosome in the cytoplasm

Eukaryotes: cells that contain a nucleus and several different membrane-enclosed organelles

Organelles: “little organs” that perform specialized functionsProkaryotic Animal Eukaryotic Plant Eukaryotic

Nucleus NucleusMitochondrion Mitochondrion

Plasma Membrane Plasma Membrane Plasma MembraneCytoplasm CytoplasmCell Wall Cell WallNucleoid Region (DNA)

Chemical Functions Photosynthesis: a process in which plants, some eukaryotic algae,

and prokaryotic blue algae nourish themselveso Requires sunlight, carbon dioxide, and watero Carbohydrates power cellular processes

Chloroplasts in plant cells contain pigments, such as chlorophyll, that are able to capture the energy of light

Chemosynthesis: a process in which certain kinds of bacteria obtain food where there is no light

Cellular Respiration: the energy in carbohydrate molecules is retrieved and used to carry out cell functions and facilitate growth

o Takes place in the cytoplasm of prokaryotes and in the mitochondria of eukaryotes

o Occurs in plants and animalso Requires oxygeno Anaerobic environment: little or no oxygeno Anaerobic respiration: process bacteria and fungi use to

survive and grow with little or no oxygen Carbohydrates are partially broken down to produce

carbon dioxide and smaller carbohydrate moleculesRequires Produces

Photosynthesis Sunlight CO2 H2O C6H12O6 O2Chemosynthesis

O2 CO2 H2S C6H12O6 H2O S

Cellular Respiration

O2 C6H12O6 CO2 H2O

4.2 The Growth and Reproduction of Organisms Asexual Reproduction: accomplished by single cell division and

produces offspring that are genetically identical to their single parent

Sexual Reproduction: mating between two parents and produces offspring that are genetically unique

Cell Division and Differentiation When cells are mature they may divide to form new cells The process of cell division ensures that each newly created cell

receives a complete set of organelles and genesSexual and Asexual Reproduction

Gametes: cells that are specialized for reproduction Female gametes are called eggs, male are called sperm Zygote: a genetically unique cell produced by the union of an egg

and a sperm

4.3 The Growth of PopulationsBirth, Death and Migration

Exponential Growth: the number of new individuals added to a population in each generation is a multiple of the number present in the previous generation

Arithmetic Growth: the number of new individuals added at each generation is constant

Population Growth Rate: the multiple by which an exponentially growing population increases (typically a percentage per year)

Doubling Time: the length of time required for a population to double in size

Birth Rate: the number of births in the population per unit of time expressed as a percentage of the population size

Death/Morality Rate: the number of individuals dying per unit of time expressed as a percentage of the population size

Immigration Rate: number of individuals entering the population per unit of time as a percentage of population size

Emigration Rate: number of organisms moving out of an area, calculated as a percentage of population size

Growth Rate = (births + immigration) – (death + emigration)Survivorship and Fertility

Survivorship: probability of an organism dying during a particular time interval

o Type I Survivorship: most likely to die of old age Common among large animals and predators that have

few enemieso Type II Survivorship: probability of dying is the same at every

age European starling, predators and diseases affect all

individuals in the population equally, regardless of their age

o Type III Survivorship: the very young have the greatest probability of dying because they are most easily taken by predators or are most vulnerable to disease

Most common observed in nature As these animals mature, they become more likely to

die of old age Fertility Rate: rate of reproduction Age-Specific Fertility Rate: number of offspring produced by females

during a particular range of ages Total Fertility Rate: potential number of offspring that an average

female in a population can produce if she survives to old age Generation Time: the average difference in age between mothers

and their offspring

9/28/14 3:29 PMEcological Communities

6.1 Competition for Shared Resources Ecological Community: the species that interact within a specific

area Intraspecific Competition: members of the same species pursue

limited resources Interspecific Competition: different species compete for shared

resourceso They may compete by interfering with one another’s ability to

access a resourceo Competing species are able to coexist because they use

different portions of their shared environmentInterspecific Competition

Russian biologist G.F. Gause devised a set of elegant laboratory experiments that provided the basis for our formal understanding of competition (1930’s)

He grew two different species of a single-celled organism, Paramecium, both together and separate

Species grew more rapidly when they were grown alone Competitive Exclusion Principle: two species that directly compete

for essential resources cannot coexist; one species will eventually displace the other

How Competitors Coexist Ecologist G. Evelyn Hutchinson provided an explanation for the

coexistence of competing organisms Fundamental Niche: the complete range of environmental

conditions, such as requirements for temperature, food, and water, over which the species might possibly exist

Hutchinson noted that few species actually grow and reproduce in all parts of this theoretical range

Realized Niche: the range of conditions where a species actually occurs given the constraints of competition

Ecological Niche: the role an organism fills within its habitat

Species whose fundamental niches overlap significantly are potential competitors. Hutchinson suggested that these potential competitors are able to coexist because they divide up the fundamental niche

Niche Differentiation: division of resourcesExploitation and Interference

Exploitation Competition: successful competitors are able to take up or utilize resources more efficiently

Interference Competition: fend off competitors with aggressive or territorial behavior

6.2 Herbivory, Predation, and Parasitism Consumers: feed on live organisms

o Exert strong selective pressure on their prey Herbivores: eat plants Predators: hunt and kill animals Parasites: live in or on other plants or animals but usually do not kill

them directlyHerbivores

Fructivores feed on fruits Gramnivores often play an important role in plant dispersal Many herbivores are grazers, feeding directly on the leaves and

young stems of plants Plants have evolved a variety of defenses against herbivores,

including thorns, irritating hairs, and distasteful or toxic chemicals Coevolution: tit-for-tat evolution of prey and the species that eat

themo Ex: Most species of milkweed produce and store large amount

of chemicals called alkaloids, which are toxic to most animals. The caterpillars of monarch butterflies feed almost exclusively on milkweed plants. The alkaloids that the caterpillars store in their tissues make the monarchs toxic to birds and other predators that otherwise might eat them

Predators Filter-feeding predators use webs or netlike structures to catch their

prey

o Spiders and their webs, shrimp trap small organisms in the hair-like setae on their legs, whales use their comb-like teeth to filter plankton from the water

When a particular prey species is abundant, predators focus their attention on it. As predation depletes that species’ numbers, the predators switch their attention to other, more abundant species

Prey Switching: provides predators with a steady supply of food; it also ensures that none of the prey species will be totally eliminated

Predation can increase the overall health of the prey population because predators pick the youngest, oldest, or sickest individuals

Parasites Viruses and tapeworms live inside the host Ticks and leeches are external Vectors: organisms that carry the parasite but are unaffected by it The spread of parasitic disease is governed by the following four

factors1. Abundance of hosts2. Accessibility of hosts3. Transmission rate of parasites4. Length of live of an infected host

6.4 The Flow of Energy in Ecological Communities Energy Flow: the transfer and transformation of high-energy organic

molecules Trophic Levels: feeding levels Food Web: feeding interactions among species in a community

Food Chains Food Chain: simple food webs depicting feeding relationships

among organisms Primary Producers: transform energy from sunlight or certain

inorganic chemicals into high-energy carbohydrateso First or lowest trophic levelo Green plants, algae, cyanobacteria, chemosynthetic bacteria

Primary Consumers: animals that feed on primary producerso Herbivores – grazing mammals and insects

Secondary Consumers: carnivores that feed directly on herbivores make up this third trophic level

Tertiary Consumers: feed on secondary consumerso Rare that communities have more than four trophic levels

Decomposers: organisms that feed on nonliving organic mattero Scavengers such as vultures, jackals, and hyenas feed on the

dead bodies of dead animalso Termites, wood roaches and others feed on plant litter, such

as fallen leaves and dead woodEnergy and Biomass Pyramids

Biomass Energy: the food that can be consumed by higher trophic levels

Trophic Level Efficiency: the fraction of energy that the organisms in one trophic level make available to the next trophic level

o Rule of thumb: 10%Keystone Species

Keystone Species: a species that has a disproportionately large effect on its environment relative to its abundance

Trophic Cascade: the populations of herbivores increase, resulting in the overconsumption of primary producers

6.5 Disturbance and Community Change Ecological Disturbances: fires, hurricanes, logging of forests Ecological Legacies: environmental features, such as soil and woody

debris, that are left behind following a disturbance Succession: process of post-disturbance change in an ecological

communityPrimary Succession

Primary Succession: occurs where a disturbance has removed virtually all ecological legacies

o Often happens over centuries, hard to study directly Pioneer Species: first to colonize previously disrupted or damaged

ecosystemso Widely dispersed, able to grow under very harsh and

resource-poor conditions, as they grow up they alter their environment in ways that allow other plants to become established

Facilitation: as plant species become established and grow, they may alter the environment around them in ways that make it more habitable for other species

Climax Community: a community of plants that is able to reproduce generation after generation

Secondary Succession Secondary Succession: the process of change following disturbances

that leave behind legacies such as soil, woody debris, or plant seeds Old-field Succession: the reforestation of abandoned farmland

Cyclic Succession Succession may increase likelihood of disturbance, which leads to

cycles of changeThe Importance of Place

Successional change at a place is affected by the changes occurring in surrounding places

9/28/14 3:29 PMEcosystem Ecology

7.1 Ecosystem Ecology and Biogeochemistry Biosphere: all of the organisms on Earth and the nonliving

environment with which they interact Biogeochemical Cycle: the flow of matter through an ecosystem

Material Pools and Fluxes Pools: the parts of an ecosystem in which matter may reside, such

as the atmosphere or soil Fluxes: the rate at which matter moves from one pool to another

o Into a pool = positive, out = negative Mass-Balance Accounting: by knowing the mass of an element in

each pool in an ecosystem and the fluxes of an element through that ecosystem, scientists can account for changes in the abundance of that element within an ecosystem

Capital: the total amount (mass) of an element or molecule that it contains (referring to a pool)

Equilibrium: when the net flux of an element is zero, and when the capital of the element in that pool remains constant

Residence time: the average time that an atom of an element or molecule of a compound spends in a pool

Cycling time: the average time that it takes an element or molecule to make its way through an entire biogeochemical cycle

Nutrients Nutrients are elements needed to carry out life’s functions (about

25) Macronutrients: elements that organisms require in comparatively

large amountso Carbon, hydrogen, phosphorus, nitrogen

Micronutrients: organisms do not require that much of ito Manganese, boron

7.2 The Rock Cycle Rock Cycle: elements within the Earth’s crust and mantle are slowly

converted from one type of rock to another Igneous Rocks: form as magma solidifies Sedimentary Rocks: when sediments, such as sand, silt, and the

remains of dead organisms, become “glued together” under pressure

Metamorphic Rocks: form when great heat and pressure transform the physical and chemical properties of sedimentary or igneous rocks

7.3 The Hydrologic Cycle Hydrologic Cycle: the distribution and flux of water through Earth’s

biogeochemical system (driven by solar energy & gravity) Solar energy drives

o The evaporation of liquid water from the ocean and lakeo The circulation of the atmosphere that carries moisture-laden

air over lando Ice to melt

Annually, total precipitation equals total evaporation Transpiration: evaporation from leaves Runoff: rainwater that falls on land may flow across the surface Groundwater: the water that gravity causes to saturate through the

soil and into the rock below Aquifer: a layer of soil or rock that is saturated with groundwater

7.4 The Carbon CycleLife Drives the Carbon Cycle

Humans have significantly modified Earth's carbon cycle by the direct use of

o High-energy carbon from ecosystemso Lando By the burning of fossil fuels (results in increase of carbon in

atmosphere) Flux of Carbon driven by life Respiration – returns to atmosphere Photosynthesis – pulls from atmosphere Gross Primary Production (GPP): the total amount of CO2 that

photosynthetic organisms convert to organic carbon each year Net Primary Production (NPP): the amount of organic carbon

available to all the non-photosynthetic organisms, or consumers, in an ecosystem

Net Ecosystem Production (NEP): the amount of organic carbon left each year after subtracting the respiration of non-photosynthetic organisms from NPP, or the net flux of carbon in an ecosystem

o Aka the difference between the carbon returned to the atmosphere (respiration) and the carbon available to all the non-photosynthetic organisms

Most Carbon stored in biomass terrestrial o Soil contains large amounts of organic carbon; plant litter,

waste, dead organisms Respiration = GPP; global NEP = 0 CO2 dissolves in oceans, lakes, and rivers 55% of carbon dissolved in oceans/lakes/rivers is consumed in NPP

by phytoplankton Phytoplankton: the photosynthetic algae and bacteria suspended in

the water Carbon is used to make shells of marine animals such as clams and

mussels

7.5 The Nitrogen Cycle Nitrogen is the most abundant element Small amounts in crust

Certain microorganisms are able to convert nitrogen gas (N2) from the atmosphere to ammonia (NH3)

Plants convert inorganic forms of nitrogen into nitrogen-containing compounds that are essential to life, such as amino acids and nucleic acids

Animals obtain these compounds by eating plants or other organisms. When the wastes and remains of organisms decay, inorganic forms of nitrogen are regenerated

These inorganic forms may be taken up by plants or return to the atmosphere as nitrogen gas

Human activities such as agriculture, the synthesis of nitrogen fertilizers, and the burning of plants and fossil fuels have significantly altered the chemical composition of the atmosphere, lakes, and streams, and have doubled the rate of nitrogen exchange between the atmosphere and biosphere

Nitrogen Transformations Nitrogen Fixation: the process in which nitrogen enters the

biosphereo Small amount caused by lightningo Mostly carried out by nitrogen-fixing bacteria

Nitrification: specialized bacteria in the soil convert NH4 to nitrite NO2

De-nitrification: the process in which nitrogen in soil and water is returned to the atmosphere

o Specialized bacteria convert NO3– to N2 gas Animals must obtain their nitrogen by eating plants or other animals When decomposers break down the remains and wastes of plants

and animals, ammonia (NH3) is released into the soil Nitrite and nitrate are particularly soluble in water, so they are

easily removed from soil and transported into streams and groundwater

The total nitrogen in Earth's organisms, soils, and waters is determined by the balance between nitrogen fixation and de-nitrification

Human Impacts Haber-Bosch Process: a non-biological method of nitrogen fixation

o Source of chemical fertilizer Because ammonium and nitrate dissolve in water, runoff from

agricultural fields eventually carries them into lakes, streams, and estuaries. Thus there are higher rates of nitrogen fixation in lakes, streams, and estuaries

Higher concentrations of nitrogen encourage the rapid growth of algae. Their growth leads to eutrophication

Eutrophication: the abundant organic matter from the algae encourages high rates of respiration by decomposing organisms

Excess nitrogen may act as a pollutant

7.6 The Phosphorus Cycle Phosphorus is abundant in crust but absent in atmosphere (unlike

nitrogen) Organisms require phosphorus in the form of phosphate (PO4) to

manufacture a variety of organic compounds The supply of phosphate available to organisms is limited by the

rate of weathering of sedimentary rocks Plants and some microbes can absorb phosphate that is dissolved in

soil water or the waters of streams, lakes, or the ocean. Other organisms obtain phosphate through the food web

Phosphate is an especially important limiting factor on ocean NPP Human use of phosphate fertilizers and phosphate-rich detergents

has significantly increased the amount of phosphate flowing in streams and rivers

Treated and untreated sewage contains large amounts of phosphate; its addition to streams also increases the supply of phosphorus

Where the growth of algae has been limited by the availability of phosphate, this enrichment can produce eutrophication similar to that produced by excess nitrogen

7.7 The Sulfur Cycle Sulfur is 0.07% of crust Most of this sulfur is chemically bound in rock minerals

Rock weathering and volcanic activity release forms of sulfur that can be used by organisms

The annual flux of sulfur through the atmosphere is high, but its residence time in the atmosphere is only a few days. Therefore, the atmospheric pool of sulfur is generally small

Humans have doubled the annual flux of sulfur through the biosphere. Although this has not increased NPP in most ecosystems, it has had significant environmental and health consequences

Mining and fossil fuel burning has doubled amount of sulfur released Source of acid rain