This we know, the earth does not belong to man. Man belongs to the earth. All things are connected like the blood that unites our family

This we know, the earth does not belong to man.

Man belongs to the earth.

All things are connected like the blood that unites our

family.

Man did not weave the web of life.

He is merely a strand in it.

Whatever he does to the web, he does to himself.

Chief Sealth - 1894

Ecology

The study of the interrelationships between living organisms and their biotic and abiotic environment.

Hierarchy of ComplexityPopulation

A group of organisms of the same species who live in the same habitat (the environment in which a species lives) at the same time.

CommunityAn association of organisms of different species living together with some degree of interdependence

Hierarchy of Complexity

EcosystemA particular community and its physical (abiotic) environment.

Biosphere (ecosphere)All ecosystems linked together by biological, physical and chemical processes.

POPULATIONS

4 factors that influence population growth

Birth rate (natality)increases

Death rate (mortality)decreases

Immigrationincreases

Emigrationdecreases

Population Growth Models

Mathematical models for testing hypotheses about the effects of different factors on population growth.

Population Growth Models

Exponential Growth Model (J-Curve)Unlimited resourcesNo predationNo diseaseIdeal conditions

Exponential Growth ModeldN/dt = rN

dN is the change in population size

dt is the change in timer is the intrinsic rate of increase (birth rate – death rate)

N is the number of individuals at any one time

Even slow breeding elephants, if begin with one pair and all descendents lived to reproduce, in 100,000 years would produce so many living descendants that they would fill the visible universe. Charles Darwin

Sigmoidal Growth CurveExponential growth of population is checked.

Sigmoidal or S-shaped.Initial rapid expansion in low densities (exponential growth phase)

Decelerating growth at higher densities. (transitional phase)

Plateau as density approaches carrying capacity. (plateau phase)

Carrying capacity Maximum density of the population that the environment can support over a sustained period of time.

Logistic (sigmoidal) growth model

dN/dt = rN (K-N)K

Opportunistic Growth ModelSmall, short-lived organisms or organisms that live in disturbed or transient habitats.

Never reach K before they crash. “Boom or Bust”

Aphids are an opportunistic speciesIf cool and moist – exponentialIf hot and dry – population crashes

Aphids

Human population growthExponential?Opportunistic?Logistic?

Types of Limiting FactorsDensity Independent

Population limited by abiotic or climatic factors such as fire, flood, temperature extremes, etc.

Opportunistic species who have a high rmax

Population never allowed to reach Kr selected species Traits that are thought to be characteristic

of r-selection include: small body size, early maturity onset, short generation time, and the ability to disperse offspring widely.

Types of Limiting FactorsDensity Dependent

Limiting factors are biotic such as predation, competition, disease, etc.

The proportion of the affected organisms increases with increasing density.

K selected speciesTraits that are thought to be characteristic of K-selection include: large body size, long life expectancy, and the production of fewer offspring that require extensive parental care until they mature

Examples California Condor

One egg every two yearsLarge birds – nest on cliffsLow population Die of lead poisoning after eating bullet-riddled carcasses; fly into power lines

Population low: 22 individuals in 1982

Current Population: 246 individuals

Life span: Unknown, possibly up to 60 years in the wild.

Wingspan: Up to 9.5 feet (3 meters)

Weight: Averages 16-23 pounds

Body Length: 46 to 55 inches

Examples Orangutan

Large primateOne birth every 5 yearsMassive habitat destruction

Examples Fungus-Eating Gall Midge

Live in mushroom beds.Parthenogenic eggs that develop inside of mother.

Feed on maternal tissue until emergence.

Midge are born with eggs already inside them.

Communities

Types of Community Interaction

Commensalism (+ o)Mutualism (+ +)Predation / Parasitism (+ -)Competition (- -)

Parasitism, commensalism and mutualism = symbiosis

Examples of Types of Community Interaction

Deer and rabbits both feed on the grass in a meadow.


Ramora fish use suction cup like structures to attach to sharks. They get a free ride to lunch.

Ramora attached to a tiger shark


Protozoans live in and digest cellulose for termites. (obligate)

Trichonympha

Mutualistic flagellated protozoan found in the gut of termites. Digest cellulose for the termite.


Fish-cleaning shrimp set up stations to remove parasites from fish.

Shrimp that cleans fish


Egrets feed off of invertebrates that cattle kick up when they walk around the pasture.

Cattle Egrets in England


Ants feed off of sugary secretion from Acacia tree and protect the tree from herbivores.

Ant sipping on sugar from Acacia

LICHENSAlgae

provide sugar and possibly nitrogen for the fungus.

The fungus helps to maintain water and minerals for the algae.

Competition

Interactions within or between populations for a limited resource. The closer the niches the more intense the competition.

Intraspecific more intense than interspecific.

Niche

Sum total of an organism’s use of its biotic and abiotic resources.

N-dimensional hypervolumeAn organism’s role not its habitat.

Fundamental niche is the entire set of optimal conditions under which an organism can live and reproduce.

Realized niche is the life style that an organism actually pursues and the resources that it actually utilizes.

Gauses’ Compeittive Exclusion Principle

One species eliminates the other one entirely when two species niches overlap and the system is allowed to go to saturation (intense competition).

Paramecium caudatum (initial K?)Paramecium aurelia (initial K?)

Paramecia – Kingdom Protista(ciliate)

Objections

Paramecia are r-selected and therefore rarely encounter saturation in nature.

If two species coexist then niches must be different (self-evident)

Poses question: How similar can two species niches be and still coexist?

Stable Coexistence

Since both species are harmed in competition, selection is for minimizing contact.

Evidence is indirect and often inferred.

Stable Coexistence MacArthur’s Warblers

5 congeners (Dendroica) appear to have the same niche.

How do they coexist?Resource partitioning

Predation

Permits energy flow from one trophic (feeding) level to another.

Predation

Regulate the population growth of the next lower trophic level Lynx and Hare

Lynx

Hare in winter

Hare in summer

Predation

Permits more species to exist within a particular habitat Spiny starfish in rocky intertidal

Spiny Starfish

Spiny starfishRocky intertidal zone in Washington State

15 prey species coexisting; starfish dominant predator (keystone species)Limpets, barnacles, bivalves and snails

Removal of starfish from selected areas resulted in reduction of prey species to 8

Prey Techniques Constant interaction between predator and prey populations selects for increased efficiency of both.

Any characteristic that increases the predator’s efficiency at detecting, capturing or eating prey would be selected for. Conversely any prey characteristics that would enhance its ability to avoid detection, capture or being eaten would also be selected for.

Prey Techniques

Escape in time. Prey has higher max population and appears in mass in an unpredictable manner. Massive reproduction followed by long absence.Cicada (13 and 17 years)

Cicada

Prey Techniques

Escape in time. Bamboo and panda bears.

Panda eating

bamboo

Intestinal Surface Area

Escape in space. Prickly pear cactus and moth larva which eats cactus.Cactus introduced in Australia in 1839.

Prickly Pear Cactus

1900 cactus covered 10 million acres.

1925 cactus covered 60 million acres and larva introduced which eats holes in cactus allowing bacteria and fungus in. Two mile range for moth.

1931 moth increases to 100 million and almost all cactus gone.

1932 moth population crashes.1935-40 oscillations dampened - equilibrium

Escape utilizing behavior. Starling and peregrine falcon. Starlings tighten flying formation when peregrines are nearby.Falcon has vision 5 times better than humans.

Stoops, closes wings and dives at speeds greater than 200 miles per hour coming out of the sun.

Prey killed instantly by jolt of talons.

Peregrine Falcon

Escape with chemical or physical defenses.Cryptic coloration or camouflageCounter shading & disruptive coloration

Disruptive & Counter shading

Escape with chemical or physical defenses.Warning or aposematic coloration

Aposematic Coloration

Escape with chemical or physical defenses. Warning or aposematic coloration

Batesian mimic – palatable species mimics poisonous species.

Mullerian mimic – two unpalatable species resemble each other

Flash patterns

Monarch and ViceroyBatesian Mimicry

Two species of Central American Passion Flower Butterflies

Mullerian Mimics (both toxic)

Plant techniques Thorns, silica and leathery leaves.

ToxinsAlkaloids (nitrogen ring): nicotine, strychnine, peyote, marijuana, chocolate, cashews. 40% of angiosperms are toxic or hallucinogenic

Ergot(above)toxic mushrooms

&peyote cactus

(right)

Plant techniques Toxins

Tannins in climax tree leaves, heartwood and bark (tanning)

Cardiac toxins – milkweed and foxglove

Milkweed plant

Succession An orderly process of community change wherein the dominant species within an area is replaced over time with other species.

Primary SuccessionOccurs in a habitat not substantially influenced by previous biotic communities.

Often on bare rock surface such as cooled volcanic lava or rock scraped clean by glacial action.

Secondary Succession

Occurs in habitats already substantially modified by a preexisting community.

Fire, logging, or abandoned field.

Secondary Succession in an abandoned field in Fairfax

From pioneer communities (r-selected, able to withstand harsher abiotic factors) to climax communities (K-selected, more able to withstand competition)

Climax communities are thought to be self-sustaining. But may be that a climax community simply changes more slowly than previous seres.

First Year

Annual and perennial weeds such as crab grass.

Second Year

Asters and ragweed (perennials)

Third – Fifth Year

Broom sedge, Queen Anne’s lace and goldenrod

6th – 25th Year

Pine Forests

100 Years

Deciduous Forest

Oaks, Hickory, Tulip, Maple and Beech

Generalizations about successionEach species modifies its environment such that it becomes more suitable for the next sere.

Exact species composition cannot be predicted

Seres advance toward more complex and more efficient ecosystems (r to K)

Increase in total biomassIncrease in number of species (biodiversity)

Biodiversity

Rapidly decreasing due to habitat destruction

Why important?

Genetic diversity from ancestral crop species

Food such as coffee, corn, pineapple, potato, tomato chocolate, rice are all tropical species

Alternative food sources (some with more protein and carbohydrates than traditional food sources) Estimated 20,000 edible species – currently 200 utilized

Medicine – genetic rouletteAesthetics – should the value of a species be judged solely on its economic value?

Quiz on populations and communities.

Ecosystems

Two basic concepts:Energy flowsNutrients cycle

Solar Energy

Ultimate source of energy for most of the Earth’s ecosystems is the sun.

Solar Energy30% is reflected back into space20% is absorbed by the atmosphere (1-3% by ozone)

50% reaches the surfaceMost absorbed by water and earth and reradiated as infrared radiation which is held in as heat.

20% absorbed by plants but only 1-2% used in photosynthesis; most re-radiated as heat or used in transpiration.

Solar EnergyEnergy flows through food chains and food webs from one trophic level to another.

Trophic levels group organisms based upon their main nutritional source.Autotroph or producerHeterotroph or consumerDetritivore or saprotroph (decomposer)

Food ChainThe pathway along which food is transferred from trophic level to trophic level, beginning with producers.

Food Chain

GrassGrasshopperToadSnakeOwl

Producerprimary consumer secondary consumertertiary consumer

quaternary consumer

Food WebThe elaborate, interconnected feeding relationships in an ecosystem.

Construct a food web.

Laws of Thermodynamics

First Law: Energy can neither be created nor destroyed.

Second Law: Every energy transformation involves some loss of usable energy in the form of heat (entropy).

Pyramid of Energy

Only about 10% of the available energy at one trophic level can be used at the next trophic level.Units are energy per unit area per unit time (J m-2 yr-1)

Where does the energy go?

Gross vs. Net ProductivityTotal amount of solar energy converted to organic compounds is called Gross Primary Productivity

The amount of Gross Primary Productivity less the cost of metabolic activities of the plant is called Net Primary Productivity.Only that sugar which is used in biomass (dry weight) can be passed to the next trophic level.

Nutrients Cycle

Carbon CycleNitrogen Cycle

NFL planting trees in Detroit to offset Super Bowl emissions

DETROIT (AP) — The National Football League says it plans to plant acres of trees in metropolitan Detroit to offset carbon emissions caused by traffic generated by next year's Super Bowl. (March 2005)

Nitrogen FixationBacteria and cyanobacteria take atmospheric nitrogen and convert it to ammonia.Rhizobium in root nodules of legumes (clover, beans and alfalfa

Cyanobacteria – blue-green algae

Azobacter – free living bacteria

Cyanobacteria – blue green algae

Beans & Rhizobium nodules

Hubbard Brook ExperimentComparison of forested area with deforested area

Plants take up and store nutrients.

Without plants, leeching increases. Hydrogen ions in water displace nutrient cations attached to soil and run off into streams.

Hubbard Brook Experimental Station

Deforested AreaRunoff four times greaterCalcium loss 10 times higherPotassium loss 21 times higherNitrogen loss 120 kg/hectare/yearCompared with accumulation of 2 kg/hectare /year in forested area.

Excessive nutrients cause algal bloom in streams.

Bioaccumulaton

Substances that cannot be metabolized by organisms (biodegraded) are passed up the food chain.

DDT

Ecological Techniques

Describe one technique used to estimate the population size of one animal species based on a capture-mark-release-recapture method.

N = Estimated population sizeN = # marked x total catch 2nd time # of marked recaptured

Seine Net - capture

Describe one method of Random Sampling used to compare the population of two plant species, based on quadrat methods.

Select appropriate sampling unit (old field) 1 x 1m square quadrat frame

Randomly sample two plants species in a community.Each group establishes a linear transect using a 50m tape from a designated point (tulip tree).

Start at a random point within the first 10m (and at every subsequent 10m point along the tape)

One member of the group should flip a coin to determine if the group will sample on the left or right of the tape.

Collect % cover as data on 5 quadrats.

Quadrats

CalculationsCalculate the mean of a set of valuesStandard deviation

Used to summarize the spread of values around the mean and that 68% of all values lie within +/-1 standard deviation of the mean. This rises to 95% for +/- two standard deviations.

A small standard deviation indicates that the data is clustered closely around the mean value.

Human Impact (biosphere)Outline two local or global examples of human impact causing damage to an ecosystem or the biosphere.

Greenhouse Effect (global warming) and Ozone Depletion.Causes and effects supported by data

Measures which could be taken to reduce the impact of the two examples.

Greenhouse Effect(global warming)

Causes: CO2,,methane,,and water vapor trap infrared radiation (heat) and reflect it back to earth.

Effects: Warms earth’s surface. Earth surface temperature

without greenhouse effect would be -18 degrees Celsius.

Increased CO2 from burning fossil fuels could increase temperatures about 2 degrees Celsius in the next 100 years if CO2 levels continue to rise at the current rate.

Possible consequencesWarming would be greatest near the poles;

the resulting melting of polar ice might raise sea level by 100m, gradually flooding coastal areas. (NY, Miami and LA.)

Major agricultural areas would change.Increase in tropical and vector borne

diseases.How prevent increase in greenhouse

gases?

Ozone DepletionOzone protects the surface of the earth

from the damaging UV radiation.Satellite studies of the atmosphere suggest

that the ozone layer has been gradually thinning since 1975.

Cause: mainly increasing levels of chlorofluorocarbons (CFCs), used for refrigeration and aerosols.

Ozone DepletionEffects: Ozone hole over Antarctica.

Magnitude of ozone depletion and the size of the ozone hole have generally increased in recent years. Now includes southernmost portions of Australia, New Zealand and South America.

Even at the more heavily populated middle latitudes, ozone levels have decreased 2-10% in the past 20 years.

Ozone DepletionConsequences:

Increases in lethal and non-lethal forms of skin cancer and increases in numbers of cataracts

Unpredictable effects on crops and communities especially the phytoplankton (source of most oxygen in atmosphere.

How can we stop ozone depletion?

Documents

This we know, the earth does not belong to man. Man belongs to the earth. All things are connected like the blood that unites our family