Chapter 4 Lecture Notes Ecosystems: How They Change

Outline of Chapter 4 A.Population dynamics B.Population equilibrium C.Evolution D.Succession E.Living beyond our means

Dynamic Equilibrium Ecosystems are constantly changing in order to stay balanced.

Succession - One species gradually replaced by another in an ecosystem primary – new ecosystem where there were no living things before. Cooled lava, receded glacier, mud slide secondary- ecosystem used to be there. Fire, humans clear an area Aquatic – (type of secondary) lakes taken over by terrestrial ecosystem Climax ecosystem- in balance only changes if major interference

Fires in Ecosystem Maintain balance of species and energy in ecosystems over the long run. Beneficial b/c provide nutrients for soil We avoid natural fires, but the problems like Crown Fires- (not natural) kill the whole tree 1988 Yellowstone fires changed climax ecosystems of white bark pine trees to huckle berries. Grizzlies ate both

Primary succession Must create new soil for plants to grow The first plants to come in are called pioneer species

The Basics of Evolutionary Change Vocabulary * DNA * Chromosome (46) * Gene –Coding region of the DNA * allele (23) – during meiosis, each egg or sperm receives one allele for each gene Central Dogma: DNA- blueprint RNA- carpenter Protein- house, pieces, wood

Each cell in an organism has the instructions.

Mutations Mutations are changes in DNA. They can occur by: * Normal variation * Chemical * UV * Radiation Genetic Trait- only passed down if an organism reproduces Good or Bad?

Why do species change? Selective pressure on DNA mutations from environmental resistance and biotic potential The time and space for evolution can be understood by knowing how old the earth is, how long life has been around, and Pangea.

Speciation example Reproductive Isolation

Understand how molecular biology (micro) relates to evolutionary change (macro) for each of these vocabulary words: 1.Adaptation 2.Genetic variation 3.Gene pool 4.Differential reproduction 5.Biological evolution 6.Selective breeding 7.Artificial selection 8.Selective pressure 9.Natural selection 10.Fitness 11.Evolution of a new species 12.Reproductive isolation