Communities & Ecosystems Our Wider World Topic 5.1

Some new terms… Species: a group of organisms that can interbreed and produce fertile offspring

What is not a species? Liger The liger is infertile. Official information http://www.youtube.com/watch?v=CD6vpheUoPE

Donkey + Horse = Mule Mules are infertile. Are they a species?

Scientific names Genus species Why give a species a scientific name if it already has a common name?

Habitat: The environment in which a species normally lives or the location of a living organism.

Population: A group of organisms of the same species who live in the same area at the same time.

Community: A group of populations living and interacting with each other in an area.

Ecosystem: a community and its abiotic environment. Abiotic: “A” – not “biotic” – living

Abiotic Factors Abiotic factors may include Temperature Water Sunlight Wind Rocks and soil

Ecology: The study of relationships between living organisms and their environment.

Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances.

Heterotroph: an organism that obtains organic molecules from other organisms.

Consumer: an organism that ingests other organic matter that is living or recently killed.

Detritivore: An organism that ingests non-living organic matter. Ex. Earthworms, Dung Flies

Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.

Decomposers Detritivores and saprotrophs are both decomposers Decomposers are necessary as they eliminate waste that would otherwise pile up. Decomposers recycle nutrients

Food Chain A diagram which shows which organism eats which by using an arrow. Only one feeding relationship is shown Arrow indicates the direction energy flows Grass  rabbit  wolf Arrows must be in the proper direction for credit

The Ultimate Source of Energy for Most

A terrestrial food chain Quaternary consumers Tertiary consumers Secondary consumers Primary consumers Primary producers A terrestrial food chain A marine food chain Start with a producer Continue with levels of consumers Arrows: A  B A is being eaten by B Why is this example unacceptable for IB? Must include species names.

Grasslands Ecosystem Food Chain Grass grasshoppers toad hognose snake hawk

Marine Ecosystem Food Chain diatoms copepods herring seal great white shark

River Ecosystem Food Chain Algae mayfly larva  juvenile trout kingfisher

Trophic Levels Trophic Level: the position an organism has in its food chain. Trophic Level T1 producer T2 primary consumer T3 secondary consumer T4 tertiary consumer T5 quaternary consumer

For a food chain to function… In which trophic level would you want the largest number of organisms? (think, pair, share)

Food Web An interconnecting series of food chains More diversity, complexity and a better representation of species interactions. Direction of the arrow still indicates transfer of energy You put the producer at the bottom of the diagram. The primary consumers fill in the next level, etc.

5.1.8 Construct a food web containing up to 10 organisms, using appropriate information. Phytoplankton is eaten by krill Krill is eaten by squid, emperor penguins, crabeater seals, Adelie penguins, ice fish, tooth fish, and humpback whales Squid is eaten by ice fish, tooth fish, crabeater seals, and emperor penguins Ice fish and tooth fish are eaten by squid, crabeater seals, Adelie penguins, emperor penguins, petrel (bird) and humpback whale Emperor penguins, crabeater seals, and Adelie penguins are eaten by leopard seals and killer whales.

Energy in Ecosystems Light is the initial energy source for almost all communities.

In a food chain… Energy originates from light, and is converted into chemical energy by producers. C

When that chemical energy (carbs, lipids, or protein) is digested, it passes from one trophic level to the next. T1: Grass T2: Horse Energy Flow C

Energy Flow Thus, energy flows up the trophic levels. Trophic Level T5 quaternary consumer T4 tertiary consumer T3 secondary consumer T2 primary consumer T1 producer Energy Flow

Chemical cycling (Chemical Energy flow) Energy is lost at each trophic level in the form of heat loss during cell respiration Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling (Chemical Energy flow) Energy flow

Energy transformations are never 100% efficient. Often only 10 – 20% of chemical energy in food is utilized. Animals lose heat as they move around. Warm-blooded animals use a lot of energy to heat their bodies. Not all parts of a plant/animal are consumed

Pyramids of Energy 10 kJ m-2 y-1 100 kJ m-2 y-1 1,000 kJ m-2 y-1 T4: Tertiary consumers T3: Secondary T2: Primary T1: producers 1,000,000 kJ m-2 y-1 of sunlight 10 kJ m-2 y-1 100 kJ m-2 y-1 1,000 kJ m-2 y-1 10,000 kJ m-2 y-1

Pyramid of Energy Used to show how quickly and how much energy flows from one trophic level to the next in a community. Shows rate and quantity Units: kJ m-2 y-1

Pyramid of Energy Since energy is lost at each trophic level, each level of the pyramid is smaller than before. Organisms DO NOT CREATE energy, they simply TRANSFER it inefficiently.

Energy enters an ecosystem as light Energy exits as heat Nutrients are recycled Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow

Nutrient Recycling Saphrotrophic bacteria and fungi (decomposers) recycle nutrients. Nutrients from soil into tree Nutrients are delivered back into soil Tree dies. Decomposers release nutrients from storage in tree

Closed vs open system The Earth is considered an open system for energy The Earth is considered a closed system for matter