Study of interactions among species Ecological succession

Food Chains and Webs • A food chain shows how each living thing gets its food. • A food chain always starts with plant life and ends with an animal.

• Plants are called producers because they are able to use light energy from the Sun to produce food (sugar) from carbon dioxide and water.

• Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers. There are three groups of consumers.

– Animals that eat ONLY PLANTS are called herbivores.

– Animals that eat OTHER ANIMALS are called carnivores.

– Animals and people who eat BOTH animals and plants are called omnivores.

• Then there are decomposers (bacteria and fungi) which feed on decaying matter.

These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients.

Producers Herbivores

1st Carnivores

2nd Carnivores

Decomposers

2o Carnivores

1o Carnivore

NUTRIENTS

• Do you know why there are more herbivores than carnivores? • What is a Detritivore?• In a food chain, energy is passed from one link to another ; and it

decreases as it is transferred• Because of the large amount of energy that is lost at each link ..

• The further along the food chain you go, the less food (and hence energy) remains available.

• Most food chains have no more than four or five links.

• A change in the size of one population in a food chain will affect other populations.

• Trophic level. The last word that is worth mentioning in this section is trophic level, which corresponds to the different levels or steps in the food chain. In other words, the producers, the consumers, and the decomposers are the main trophic levels.

Food Webs• interdependent and complex food chains that look more like a web and

are therefore called food webs. A food web that shows the energy transformations in an ecosystem looks like this:

The Ecological Pyramid• Ecological pyramids are graphical representations of the number of individuals

in different nutritional levels.

• This pyramid helps one visualize the fact that in an ecological system there need to be many producing organisms at the bottom of the pyramid to be able to sustain just a couple of organisms at the top

Types of Ecological Pyramids

• Number pyramid

                                                                                                                   

             

Biomass pyramid.

                                                                                                                    

               

Energy pyramid.

                                                                                                                  

             

http://www.howe.k12.ok.us/~jimaskew/biogram32.jpg

Energy

Energy = the ability to move matter

Kinetic energy = energy in action or motion (light, heat, physical motion)

Potential energy = energy in storage (water behind a dam, stretched rubber band)

Forms of energy

Energy Conversions

Energy obeys Laws (Laws of Thermodynamics)

First Law: (CHANGE) Energy is neither created nor destroyed but may be converted from one form to another. NO FREE LUNCHES!

Second Law: (LOSS) In any energy conversion, you will end up with less usable energy than you started with. YOU CAN ‘T BREAK EVEN!

First law: energy neither created nor destroyed

Second law and entropy

Second law of thermodynamics: in every energy conversion, useful energy is always lost.

Entropy = increase in the disorder of a system

In every energy conversion, there is a gain in entropy

Second law and entropy

6 CO2 + 6 H2OC6H12O6 + 6O2 + 6 H2O

High potential energy molecule

Low potential energy molecules

Oxidation of glucose

Fig. 3-16

Energy transfer between trophic levels is not 100% efficient

Energy Flow in Ecosystems

Producers as chemical factories.Energy changes in organisms and ecosystems (Fig 3-12)

INVESTIGATING OTHER BIOTIC RELATIONSHIPS…

GROUP 1: Mutualism GROUP 2: Parasitism GROUP 3: Commensalism GROUP 4: Co-evolution GROUP 5: Mimicry GROUP 6: Camouflage GROUP 7: Predation GROUP 8: Secondary Structures

Species Competition – generally reduced by Each species living in its own habitat or niche

Competitive exclusion– No two with identical living requirements can occupy the same

ecological niche indefinitely.– Eventually, one will be excluded by the other as a result of

interspecific competition for limited resources. Resource partitioning

– Relates to evolutionary change in species in response to selection pressures generated by interspecific competition;

– Differences in resource use between species regardless of the origins of the differences.

Territoriality – Species defend their territory (any sociographical area that an

animal of a particular species consistently defends against others);– Patterns of boundaries

Resource PartitioningFive species of warblers reduce the competition among themselves

by feeding at different levels and on different parts of trees.

What is territoriality?

Territory refers to any geographical area any specie consistently defends against conspecifics (and, occasionally, animals of other species).

Animals that defend territories in this way are referred to as Territorial.

Siamese Fighting Fish