Chapters 3,4 & 5

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3-1 What is Ecology?

! The study of the interactions among organisms and between organisms and their environment

!

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Levels of Ecological Organization

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3-2 Energy Flow

main source of energy

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1. Autotrophs (Producers): make their own food from the energy in the environment

! Photosynthesis in plants & Chemosynthesis in several types of bacteria

2. Heterotrophs (Consumers) dependent on other organisms for food A. Herbivores: plant eaters B. Carnivores: meat eaters C. Omnivores: both plant and meat eater D. Detritivores: feed on plant and animal remains

(earthworms, snails & crabs) E. Decomposers: break down organic matter so that

the nutrients can be recycled (bacteria & fungi) 5

Feeding Relationships (Energy Transfer)

Food chain: a series of steps in which organisms transfer energy by eating and/or being eaten !!!Food web: the feeding relationships among

organisms in an ecosystem; a network of interconnected food chains

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3. Trophic levels: each step in a food chain or food web

! each consumer depends on the trophic level below it for energy

! Energy flows through an ecosystem in one direction

! Energy is NOT recycled!

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Energy Pyramid1. Only about 10% of the

energy available within one trophic level is transferred to organisms in the next trophic level

2. Organisms use energy for life processes and some of it released into the environment as heat !!

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Biomass Pyramid! represents the amount

of potential food available for each trophic level in an ecosystem

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Pyramid of Numbers! shows the relative

number of individual organisms at each trophic level

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3-3 Cycles of Matter

! Water Cycle ! Carbon Cycle ! Nitrogen Cycle ! Phosphorus Cycle !

Unlike the one way flow of energy, matter is recycled within and between ecosystems

through biogeochemical cycles.12

All living things require water to survive13

Carbon is the key ingredient in living things 14

Nitrogen Cycle

Organisms require nitrogen to make amino acids which are used to build protein 15

Nitrogen Cycle

! decomposers play a crucial role in the nitrogen cycle

! nitrogen fixing bacteria make nitrogen usable for producers

! denitrifying bacteria put nitrogen back into the atmosphere

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Phosphorus is an essential component of DNA & RNA

4-2 What Shapes and Ecosystem! Ecosystems are influenced by biological (biotic) and

physical (abiotic) factors ! Together, biotic and abiotic factors determine the

survival and growth of an organism and the productivity of the ecosystem in which the organism lives

! An organism’s habitat includes both biotic and abiotic factors

! Each organism has a niche (an organism’s role in the environment)

! no two species occupy the same niche in the same habitat

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Community Interactions ! Competition occurs when organisms

attempt to use the same resource at the same time an can powerfully affect an ecosystem

! Predation is the interaction between predators and prey (the predator’s food)

! Organisms living in symbiosis influence the survival of organisms and can affect ecosystems

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Competition for Food

Predator-Prey Relationship

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Mutualism: both species benefit !!!!!

! Bee & Flower Clownfish & Sea Anenome !

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Commensalism- one species benefits and the other is not affected

!!!!!!

Barnacle & Whale Shark and Remora

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Parasitism: one species benefits and the other is harmed

! The parasite obtains its nutritional needs from the host !!!!!!

Mosquito & Human Tick & Dog25

Primary Succession■ occurs on surfaces where no soil exists !

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Secondary Succession■ occurs when a disturbance changes a community

without removing the soil ■ Example: forest fire, clear-cutting a forest, abandoned

farm land

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Ecological Succession■ Organisms in each stage of succession modify the

environment making it less suitable for themselves and more suitable for organisms in the next stage

■ The result of ecological succession is a mature, stable community known as the Climax Community which continues to undergo changes as a result of the balance of nature

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4-3 Land Biomes

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4-4 Aquatic Ecosystems

Freshwater Ecosystems

Flowing Water (rivers & streams)Standing Water (lakes & ponds)

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Freshwater Wetlands

Bog

Marsh

Swamp

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Estuaries Salt Marsh

Mangrove Swamp

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Marine Ecosystems

The Great Barrier Reef

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5-1 How Populations Grow

Characteristics of Populations 1. Geographic distribution 2. Population Density 3. Growth rate Population size is affected by:

! # of births ! # of deaths ! immigration/emigration

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Exponential Growth- J shaped curve

■ under ideal conditions populations will grow exponentially

■ Ideal conditions = abundant space, unlimited resources, & protection from predators

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Logistic Growth (S shaped curve)■ occurs when population growth slows or stops after a

period of exponential growth ■ due to limited resources ■ population fluctuates around carrying capacity

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5-2 Limits to Growth

■ Density Dependent ❑ Competition ❑ Predation ❑ Parasitism ❑ Disease

■ Density Independent ❑ Weather ❑ Natural disasters ❑ Seasonal cycles ❑ Human activities

Limiting factors cause population growth to decrease

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5-3 Human Population Growth! World Population = over 7.2 billion

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China, India and the United States are the top 3 contributors to human population growth