Biotic potential: definition
Maximum rate at which a population can grow (given ideal conditions)
Biotic potential: factors
- Age at which reproduction begins
- Life span during which reproduction is possible
- Number of reproductive periods in a lifetime
- Number of offspring possible each time
R-strategists
- Reproduce rapidly when environment is uncrowded
- E.g., insects
- Many small young
- Little to no parenting
- Rapid maturation
- Reproduce once
K-strategists
- Maximize population size near carrying capacity
- E.g., mammals
- Few large young
- Intensive parenting
- Slow maturation
- Reproduce many times
Competitive exclusion principle
Developed by G.F. Gause. Two species cannot coexist in a community if they occupy the same niche. Either one species goes extinct, or it evolves to occupy another niche
3 passive defenses of animals
- Aposematic colouration: bright colours warn of poison
- Batesian mimicry: harmless animal copies colour of poisonous one
- Mulleran mimicry: multiple poisonous species look similar
Primary ecological succession
- Rebuilding begins in a lifeless area where soil has been removed
- First to inhabit are lichen
- Soil develops as rocks weather and organic matter accumulates from decomposed remains of pioneer organisms
- Once soil is present, pioneer organisms are overrun
Climax community
Final stable community once ecological succession is complete
Secondary ecological succession
Rebuilding of an ecosystem where soil is still intact
Marine biome
- Largest
- Most stable due to high heat capacity of water
- Provides most of food and oxygen
- Open oceans are nutrient poor compared to land
Tropical rain forest
- Near equator
- Abundant rain, stable temperatures, high humidity
- Only 4% of area, but 20% of carbon fixation
- Most diverse
- Tall trees that form dense canopy. Trees covered with epiphytes
- Rapidly declining due to human impact
Desert
- Most extreme temperature fluctuations
Temperate grasslands
- In both temperate and tropical regions
- Low rainfall, inhospital for forests
- Bison, antelope, wildebeest, gazelle, prairie dogs
Temperate deciduous forest/Boreal forest
- Trees lose leaves in winter
- South of Taiga, more species
- Vertical stratifigation
- Rich soil
- Squirrels, deer, foxes, bears
Conifer forest/Taiga
- Northern regions, cold winters
- Largest terrestrial biome
- Moose, lynx, elk, wolverines, porcupines
Tundra
- Permafrost, little rainfall
- Abundant insects. Birds come here in summer to eat insects
- Number of organisms is high, but number of species is low
- Reindeer, caribou, polar bears, lemmings
Nitrogen fixing bacteria
Live in nodules of legume roots, convert nitrogen gas to ammonium
Nitrifying bacteria
Convert ammonium to nitrite to nitrate
Denitrifying bacteria
Convert nitrate to nitrogen gas
Decomposers
Break dead organic matter into ammonium. Consume oxygen
