Ecosystems

All of the organisms living in an area together with their physical

environment.

Components of an EcosystemBasic components for survival of any ecosystem:

• Energy (usually from the sun)• Mineral nutrients• Carbon dioxide (CO2)• Water• Oxygen• Living organisms

Factors in an Ecosystem

• Biotic Factors : living things and parts of once living things

• Animals• Plants• Leaves• Waste• Decomposing organic matter

Factors in an Ecosystem

• Abiotic Factors : nonliving parts of an ecosystem

• Air• Water• Light• Sand/soil• Light• Temperature

ALL THINGS IN AN ECOSYSTEM ARE CONNECTED

• See example sited on pp 99 of the environmental science text

Water CycleAn Abiotic cycle

PhotosynthesisHow a Biotic organism uses abiotic factors.

Food Chain

How are toxins moved through the water cycle and photosynthesis?

• Percolation- seepage through soil into aquifer• Runoff – movement of toxins away from source• Absorption – into soil where it can leach over time

or become concentrated over time• Water flow – underground and above ground

streams, rivers, creeks• Water storage – pooling and concentration• Food contamination – contamination of producers

results in contamination of entire food chain

Graded Questions

• Why are acorns important to the control of gypsy moths?

• How do acorns result in an increase in the number of cases of lyme disease in humans?

• How do the biotic factors in this example move across ecosystems?

• How do the abiotic factors in this example move across ecosystems?

ANSWERS• Mice eat acorns and so large crops of acorns provide the food source for a larger population of

mice. Mice also eat gypsy moths and so a larger population of mice with result in fewer moths.• Deer also eat acorns, so a large crop of acorns will also support a large population of deer.

Deer carry the tick parasite. The young ticks transfer from the deer to the mice. The mice carry Lyme disease and can infect the young ticks. Later, infected ticks can bite humans and infect the humans with Lyme disease

• Mobile organisms include the deer, mice and ticks.

• The mobile organisms both move in and out of neighboring ecosystems as well as carry disease, parasites, seeds and soil into these ecosystems.

• Abiotic factors also move across ecosystems as weather, air and rain move across ecosystems. These abiotic factors can carry seeds, pollen, soil, pollution and other components from one ecosystem to another.

Organizational Heirarchy of Biotic and Abiotic Factors

• Community• Population• Species• Organism• Organ System• Organ• Tissue• Cell• _______________________• Organelle• Molecule• Atom• Subatomic Particle

Graded Questions

• Define the biotic terms listed above.• Who was Carolus Linnaeus?• After viewing the polar bear habitat below, list

the biotic and abiotic factors you can see.

Natural Selection• Individuals within a species vary slightly from one to

another• Some variations are genetic or inherited (adaptation)• Some individuals, because of certain traits, are more

likely to survive and reproduce than others• More offspring are produced than live and grow up to

reproduce• Nature selects certain traits, such as sharper claws, lighter

wings, camoflauge, beak type, because organisms with these traits are more likely to survive and reproduce

Examples

• London moths

Graded Question

• How is natural selection related to the process of evolution?

Coevolution• When organisms evolve in response to

long term association with each other.

Example• The acacia tree provides shelter and food for the ants, while

the ants protect the acacia tree from potential herbivores and parasites. More specifically, the tree has evolved swollen hollow thorns that provide shelter for the ants, and unusual sources of food such as extra-floral nectaries and leaflet tips. These adaptations appear to have evolved as a response in order to keep this relationship. At the same time, the ant seems to have evolved the ability to attack herbivores and the capacity to remove parasitic fungi from the leaflet tips of the acacia tree. Both species have evolved unique adaptations due to selection pressures from their relationship.

• Natural Selection can be a result of environmental pressures such as available food sources as in the case of the Galapagos Finches studied by Darwin.

Example

• Darwin’s Finches

• Natural Selection can be reproductively pressured as in the case of a male peacock.

The flashy tail of a male peacock actually makes the peacock easier to see for predators. However, the pressure to attract a female and thus pass on peacock traits causes the flashy tail to be selected. The less flashy tails may result in less predation, but those males may not succeed in attracting a female so those genes do not get passed on.

Male Peacock

Artificial Selection

• The selective breeding of organisms by humans for specific characteristics.

Pros and Cons of Selective Breeding

• Pros:• Select for desired trait• Increase amount of produce through increase in size of fruit or

animal• Reduce amount of land needed to farm or raise livestock••• Cons:• Reduce genetic variation • Weaken immune system• Some weaker genes may become prominent• In selecting for one advantage, you may lose other advantages

Evolution of Resistance

• The ability of one or more organisms to tolerate a particular chemical designed to kill it.