Environmental Science Living Things in Ecosystems

1. LaVigne Environmental ScienceLiving Things in Ecosystems Chapter 2 Notes #3 10/09/08

2. 2.1 Ecosystems

3. Biotic/Abiotic interactions • Limiting Factors • Anything that controls a population • Rain • Food • F ire • ???? • Carrying Capacity • # of a species that can be kept in an ecosystem • Most populations vary above and below the carrying capacity but stay near it.

4. 2.2 How species interact with each other • 5 Major Interactions Among Biotic Factors in an Ecosystem • Predation • Competition • Parasitism • Mutualism • Commensalism

5. 5.3 Adapting to the Environment • Charles Darwin • an English naturalist (1859) • Sailed on the HMS Beagle 1600’s • King wanted inventory of his territory • Sailed to all British colonies • Saw many different types of plants & animals • Darwin’s Observations • Saw finches on the Galapagos Islands • Noticed that each island had finches that all fit the food available on that island • How can different beaks be on the same type of finch?

6. 5.3 Adapting to the Environment • Darwin tried to make sense of his observations • He proposed that the environment exerts a strong influence over which individuals have offspring • Natural Selection – some individuals because of certain traits are more likely to survive & have offspring than others • (there’s unequal survival/reproduction that results from the presence or absence of particular traits)

7. 5.3 Adapting to the Environment • over many generations characteristics change- evolution • adaptation – inherited trait increases an organisms chance of survival & reproduction in a certain environment • Bears • Similar animals in different environments have different adaptations • Polar bear- white, big feet, large size • Black bear- black, small feet, medium size • Each has gone through selection over a long time in their environments

8. 5.3 Adapting to the Environment

9. 5.3 Adapting to the Environment • species can evolve in response to each other = coevolution • Ex. A plant starts creating a chemical to prevent animals from eating it and then the animal gains the ability to detox itself from the chemical • Ex. Cabbage butterfly caterpillars can break down mustard oils, when many other animals cannot – so it can feed on plants that other animals cannot • extinction – irreversible disappearance of a population or species

10. 5.3 Adapting to the Environment • Theory of Evolution Based on Natural Selection • Overproduction • Variation • Reproduction (passing on variation) • Some variations are helpful • Helpful variations make up more and more of the population as time goes by

11. 5.3 Adapting to the Environment • Antibiotics • Dr. prescribes antibiotics and says “take these until they are all gone in 10 days” • After 5 days you feel better • Should you stop taking the pills? • If you stop you may be helping select a stronger version of your illness!!!! • Why? • Antibiotics are prescribed to help you by killing bacteria. • After 5 days the weaker bacteria are dead, there are few left, and you feel better. • THE STRONG BACTERIA ARE ALIVE! • By not killing off all the bacteria you are helping to breed a stronger strain!

12. Assignments • Complete the 2.2 Section review (#1-4) • Definition of each interaction + ex on the back • Hand it in • Complete and hand in the video worksheet packet from yesterday. • Complete the 2.3 section review (p 46, 1-4) • Complete the Transparency ws #3