Ecology Introduction

Chapter 18

Ecology

– the study of the interdependence of living organisms

– the interdisciplinary scientific study of the distributions, abundance and relations of organisms and their interactions with the environment

Biological levels of organization

Sponge Bob Ecology?

Organism

Population Community

Ecosystem

"It is an obvious truth, which has been taken notice of by many writers, that population must always be kept down to the level of the means of subsistence; but no writer that the Author recollects has inquired particularly into the means by which this level is effected..." -- Thomas Malthus, 1798

Interdependence

• All living organisms interact with other living organisms

Parts of an Ecosystem

• Biotic factors– Living things that affect the organisms

• Abiotic factors– Non-living things that affect the organisms

• Biotic and abiotic factors are interdependent

The Niche

• A niche is a way of life• Includes all aspects of lifestyle– Range of tolerable conditions– Means of acquiring resources– Number of offspring– Interactions with environment– Time of day of activity– And on and on and on and …..

Changing Environments

• Tolerance curve– Set of boundaries that organisms require for

survival

Acclimation

• Tolerance curves can be affected– Acclimation– Homeostasis

0 10 20 30 40 500

10

20

30

40

50

60

Acclimated to 5° CAcclimated to 25° C

Surviving Outside the Tolerance Zone

• Escape– Migration– Hibernation

Niche differences

• Specialists–Have very narrow

niches and tend to specialize on utilizing a resource other organisms are unable to use.

Niche differences

• Generalists–Have broad niches

and can tolerate a wide range of conditions

Energy Transfer

Producers

• Photosynthesis• Chemosynthesis

Measuring productivity

• Biomass– Mass of organic material produced in an ecosystem

• Gross primary productivity (GPP)– Rate at which producers capture solar energy and

produce organic material• Net primary productivity (NPP)– Rate at which biomass accumulates– Kcal/m2/yr= GPP– rate of respiration in producers

Net Primary Productivity

Estuary

Tropical rain forest

Savanna

Woodland and shrubland

Lakes and streams

Tundra

Desert Scrub

0 1000 2000 3000 4000 5000 6000 7000 8000 900010000

NPP (kcal/m2/yr)

NPP (kcal/m2/yr)

Consumers

• Herbivores- eat producers• Carnivores- eat consumers• Omnivores- eat producers and consumers• Detritivores- eat dead stuff or excrement– Decomposers- break down complex organic material

Energy Flow

• Trophic levels– Indicates the number of energy transfers

• Only 10% of the energy in one level is available to the next

Tertiary consumers

Secondary

consumers

Primary consumers

Producers

Food Webs

• Interweaving diagram of food chains

fox owl stoat

rabbit

rat

beetle

Energy and Nutrient Flow Patterns

Consumers

Decomposers Inorganic Nutrients

Producers

Energy and Nutrient Flow

Energy

Nutrients

Consumers

Decomposers Inorganic Nutrients

Producers

Energy and Nutrient Flow

Energy

Nutrients

Energy does not cycle

95%

90%

90%

Energy Flow: Food Chains

Ener

gy F

low

: Foo

d w

ebs

Matter Does Cycle

• Most important– Water– Carbon– Nitrogen– Phosphorous– Sulfur

Water Cycle

Biog

eoch

emic

al C

ycle

s: N

itrog

en