Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download presentation
Document related concepts
no text concepts found
Transcript
First hour exam Friday Feb 8 noon here 100 points (of 500 for semester) 29 questions 57 bubbles TEST REVIEW TBA Conflict Exam If University-approved conflict http://life.uiuc.edu/animalbiology/105/ SignID: up eee105 with Karin Nelson byPassword: Wednesday’s lecture prAIRie EEE 105 Ecosystems Lec 8 01FEB02 Read Chpt. 5 http://life.uiuc.edu/animalbiology/105/ ID: eee105 Password: prAIRie Temperate grassland = prairie Prairie Illinois: Oak-hickory forest vs. Prairie grassland Drought & fire favor prairie http://www.inhs.uiuc.edu/~kenr/tallgrass.html Prairie 22 million acres of Illinois were once prairie Now 2,000 acres Primary Succession -- terrestrial Life colonizes barren land Lichens Succession after retreat of a glacier Retreating glacier Barren moraine Lichens Invading alders Alder thickets Spruce forest Secondary succession Life returns following a disturbance Population Ecology Lec 9. 12Sep01 Chapter 6 http://life.uiuc.edu/animalbiology/105/ ID: eee105 Password: prAIRie Demography How will a population change? Growth or decline? All species are capable of rapid population growth Biotic potential = Maximum reproduction rate All offspring survive N time rt : N = N e Exponential growth t t Biotic potential = Maximum reproduction rate All offspring survive N time One pair of houseflies on February 1 June 1: 191,000 x 1015 Biotic potential = Maximum reproduction rate All off spring survive N time 79 100 starfish 15 generations 10 = the number of electrons in the universe Biotic potential Almost never happens But can occur for short periods when a species invades an open niche e.g. zebra mussel Zebra mussel 2000 Biotic potential Almost never happens can occur for short periods when a species invades an open niche e.g. zebra mussel More realistic population growth: birthrate > death rate Carrying capacity death rate = birthrate birthrate > death rate density-dependent limiting factors Predation regulates prey populations predation is “good” for the prey removes old , diseased, young density-dependent Predation regulates prey populations predation is “good” for the prey removes old , diseased, young density-dependent predator/prey interaction Disease regulates populations disease is “good” for the prey removes old , diseased, young density-dependent predator/prey interaction epidemic waves Energy Food chain Photosynthetic food chain Trophic levels producer E primary consumer secondary consumer parasites respiration parasites parasites decomposition autotroph herbivore predator each trophic level regulates population of its prey parasites (diseases) regulate population of hosts Population density also changes behavior Rats in 1/4 acre pens all the food & water they need N K 5,000 150 social behavior destroyed t Predators can also regulate diversity of their community e.g. marine rocky coast intertidal zone Predators can also regulate diversity A tide pool dozens of species a diverse community Starfish prey on mollusks when starfish removed dozens of species a diverse community Starfish prey on mollusks when starfish removed mussels overgrow everything many species wiped out Starfish are keystone predators They promote species diversity
Related documents