Introduction to Ecology

Ecology

• The study of all components (abiotic

and biotic) within a defined area.

• Basic organization:

BiosphereBiomesEcosystems

CommunitiesPopulationsIndividuals

6 major terrestrial biomes

• TRF

• Desert

• Tundra

• Deciduous Forest

• Coniferous Forest

• Grasslands

• Temperature

• Water (precipitation)

• Soil

Aquatic Biomes

• Major distinction is whether water is fresh or salt

• Estuaries: any where freshwater meets saltwater.

Marine Zones

A)Intertidal/Neretic – highly photic has

contact with coast

B) Open Sea/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

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&

omnivores

• Tertiary consumers~ carnivores&

omnivores

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

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