Introduction to Ecology

Ecology

• The study of all components (abiotic

and biotic) within a defined area.

• Basic organization:

BiosphereBiomesEcosystems

CommunitiesPopulationsIndividuals

Scales of Ecological Organization

Of which level is this an example?

6 major terrestrial biomes

• TRF

• Desert

• Tundra

• Deciduous Forest

• Coniferous Forest

• Grasslands

Brain storm!

• What do you think the 3 main traits

that help distinguish one biome

from another?

• Temperature

• Water (precipitation)

• Soil

Aquatic Biomes

• Major distinction is whether water is fresh or salt

• Estuaries: any where freshwater meets saltwater.

Marine Zones-know technical

terms!A)Intertidal/Neretic – highly photic has

contact with coast

B) Open See/Oceanic – photic but no

contact with the coast

C) Open Sea/Pelagic - non-photic no

contact with land

D) Deep sea/Benthic - non-photic, cold

temps and high pressure

Marine Zones are based on

what 2 main traits?• Depth

– Light

– Pressure

– Temperature

• Contact with

coast

Which of the marine only sub-divisions

will have the most life? Why?

Energy

• What governs the type, abundance

and relationship between living and

non-living things?

• The available energy!

• Therefore we can label biotic items in

each ecosystem by their energy

needs.

• Trophic = energy!

Trophic Levels

• Primary producers~ the trophic level

that supports all others; autotrophs

• Primary consumers~ herbivores

• Secondary consumer-carnivores

• Tertiary consumers~ omnivores

Notice arrow

direction!

Clean up crew!

• Detritivores- (Detritus feeders) aka

scavengers-EX:

– Larger –will be regulated on energy

pyramid (as secondary consumer)

because of size.

• Decomposers- EX:

– Smaller-does not get regulated on energy

pyramid because of size.

• BOTH heterotrophs that feed on non-

living organic matter…..

Relationships (Community)• Trophic structure / levels~ feeding relationships in

an ecosystem as trophic means “nourishment’.

• Food chain~ trophic level food pathway, linear

• Food Web- many food chains

Energy Flow• Ecological efficiency:

% of E transferred from one trophic level to the next (10% gets through, called the 10% Law)-multiplicative loss per level

• We have 3 diagrams to illustrate efficiency and numbers of organisms/energy:

Pyramid of Energy/productivity: shows the

amount of retained and available energy per

trophic level. (Measured in Joules –J)

Pyramid of Biomass: shows actual weight of

what each trophic level contains

Pyramid of Numbers: Shows the actual

number of each type of organism on each

trophic level

Complete the final concept map on your

own, check your answers with Mrs. Jewett

when it is complete

Biotic potential

• What is “biotic potential”?

• Don’t all organisms want to maximize

this?

• If they DID, what would their growth

look like if we graphed “# of animals

over time”?

• So, why DOESN’T it look like that for

most animals?

Population Growth Models

Exponential model • idealized

• Called “r populations” (J-curve)

Logistic model• realized

• Called “K populations”

(S-curve)

Which one happens most often? Why?

Strategies to increase biotic

potential

• r-selected (opportunistic)

• Short maturation &

lifespan

• Many (smaller)

offspring

• No/little parental care

• High death rate

• EX:?

• K-selected (equilibrial)

• Long maturation &

lifespan

• Few (larger)offspring;

• Extensive parental care

• Low death rate

• EX:?

Population limiting factors-

Environmental resistance!• Density-dependent

factors: • limited food water, shelter •predation • disease

• Density-independent factors •weather/climate

• These factors lead to K*

• (*K=The max number of individuals an area can sustain/Carrying capacity)

• Biotic potential vsEnvironmental resistance! (All life must deal with this)

• Leads to adaptation

More ways to increase success is to

partake in Symbiosis. (2 unrelated

organisms living close together.)

Mutualism

+/+ both species benefit

Commensalism

+/o one species benefits, the other is unaffected

Parasitism

+/- one species benefits, the other is harmed

Neutralism

o/o Neither organism benefits or is hurt

Mutualism

Commensalism

Parasitism

Neutralism

Types of competition:• Intra-specific competition: occurs

among organisms belonging to the

same species.

• Inter-specific competition: occurs

between organisms from different

species (predator-prey)

Competition reduction• Resource partitioning~

species consume slightly

different foods or use other

resources in slightly different

ways (Develop niches)

• Character displacement~

sympatric species tend to

diverge in those

characteristics that overlap

Ex: Anolis lizard sp. perching sites in

the Dominican Republic

Ex: Darwin’s finch beak size on the

Galapagos Islands

Predator/ Prey relationships-

special competition

Predator & Prey –Evolutionary Arms Race, adaptation

at its best!

• Both predator and prey develop strategies to live!

(behaviorally and physically)

• Camouflage, weaponry, warnings, shells, stealth,

ambush! (Active versus passive defense and/or killing

strategies)

• Natural Selection will select for beneficial traits which

lead to greater fitness

5 Types of specific coloration

adaptations:

• Aposematic coloration – Stay away color

• Batesian mimicry – copy cat, only 1 bad

• Mullerian mimicry – 2 poisonous resemble

one another

• Camouflage – blend in

• Disruptive coloring – obscures size or shape

of organisms body.

Aposematic

coloring

• poison dart frog

Batesian mimicry

Mullerian mimicry

So all of these adaptations

lead to the potential

increase in what?

Demography: factors that affect

growth and decline of populations

Birth Rate - # offspring produced (natality)

Death rate – number of organisms that die

(mortatlity)

Age

structure –relative

number of

individuals

of each age

Survivorship curve – plot of numbers that

still alive at each age

• Type 1 –Death

more likely at old

age

Type 2 –Death

equally likely at

all ages

• Type 3 –Death

more likely at

young age

Where would you place k selected and r

selected populations?

Chemical Cycling

Biogeochemical cycles: the various nutrient

circuits, which involve both abiotic and

biotic components of an ecosystem

• Water

• Carbon

• Nitrogen

• (Phosphorous)

.

Nitrogen Cycle• Nitrogen enters the atmosphere, in gaseous form

N2. It has to be transformed into a usable form for organisms to use.

• Nitrogen fixing bacteria convert N2 into NH4 in a process called nitrogen fixation.

• NH4 is also produced by decomposers when breaking down organic matter in a process called ammonification.

• Different bacteria take NH4 and covert it into nitrite (NO2

-) and nitrate (NO3-) in a process called

nitrification. (This allows producers to use the nitrogen now, assimilation)

• Denitrifying bacteria convert nitrate (NO3-) back to N2 for release back into the atmosphere.

Succession Video

Big Changes in the system• Primary

succession- going

from nothing (no

soil)to pioneering

community to

climax

community.

• Why would there

be nothing???

– Melting glaciers

– Volcanic

eruptions

– Landslides

– Strip mines

• Secondary Succession - Re-establish an

ecosystem after a disturbance

• What could be a possible disturbance?

– Flood

– Fire

• Population dispersion refers to how a population is spread in an area. (Density)

Geographic dispersion of a

population shows how individuals

in a population are spaced.

Clumped

dispersion

Uniform

dispersion

Random

dispersion

clumped

There are three types of dispersion.

uniform

random

Estimating number of

individuals in a population• Why would we want to know how

large a population is?

• So HOW do we determine how large a

population is?

3 major ways:

1) Random Sampling

2) Point Intercept

3) Mark & Recapture (Lincoln index)

Random Sampling• Take the area you are

analyzing. Divide it into

equal quadrants.

• Randomly select a specific

number of subdivided

quadrants, count all

organisms in those areas.

• Add up all organisms

counted, divide by # of

quadrants than X by total

quadrants.

• 8/4=2 X16=32

• Actual = 26

• PROBLEMS?

Point Intercept

• “Draw” a line 10 meters out

• Count every organism that falls along

the line.

• Total numbers of each species and

multiply this number by total square

area counting.

• EX: __________________________

PROBLEMS?

Capture mark-recapture

(Lincoln-Petersen index)

• In a given area, capture a specific number of

organisms, mark them and release them back into

the wild

• Over a set amount of time, recapture a preset

number of organisms and keep track of how many

have already been captured. (They have marks)

• Use math to estimate total population in an area.

• Problems?

Fishing with Electricity

• 39-50 seconds