Environmental Science Living Things in Ecosystems Chapter 2 Notes #3 10/09/08 LaVigne

2.1 Ecosystems

Biotic/Abiotic interactions ► Limiting Factors  Anything that controls a population  Rain  Food  Fire  ???? ► 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.

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

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?

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)

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

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

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

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!

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