Ecology Flashcards
What is population defined by?
Size, density, and dispersion
Size
Total number of individuals in a population: births, deaths, immigration, emigration
Density
Number of individuals per unit area or volume
Dispersion
Pattern of spacing of individuals: clumped, uniform random spacing
Biotic potential
The maximum rate at which a population could increase under ideal conditions
What factors influence a population’s biotic potential?
- Age at which reproduction begins
- Life span capable of reproducing
- Number of reproductive periods in lifetime
- Number of offspring capable at 1 time
Carrying capacity(K)
The maximum that the environment can support
r-strategists
- Reproduce rapidly when uncrowded and resources are vast
- Many, small young
- Little parenting
- Rapid maturation
- reproduce once
- Insects
K-strategists
- Maximize population size near the carrying capcity
- Few, large young
- Intensive parenting
- slow maturation
- Reproduce many times
- Mammals
Limiting factors
- Limit population growth
- Density-dependent factors and Density-independent factors
Density-dependent factors
- Increase directly as the population density increases
- Competition for food, buildup of wastes, predation, disease
Density-independent factors
- Occurence is unrelated to the population density
- Natural disasters
Population interactions
Competition, predation, parasitism, mutualism, commensalism
G. F. Gause
Competitive exclusion principle
Competitive exclusion principle
-2 species can’t coexist in a community if they share a niche, if they compete for the same resources
What happens if 2 species share the same niche in a community?
- extinction
- Evolve through natural selection to exploit different resources - resource partitioning
- character displacement(divergence in adaption)
Character displacement
adaptive radiation
Resource partitioning
Evolve through natural selection to exploit different resources
Passive defenses against predators
- Aposematic coloration
- Batesian mimicry
- Mullerian mimicry
Aposematic coloration
Bright coloration of poisonous animals is a warning that predators should avoid them
Batesian mimicry
- Copycat coloration
- Harmless animal mimics the coloration of a poisonous animal
Mullerian mimicry
2 or more poisonous species resemble eachother and predators learn to avoid any prey with that appearance
Detritivores
-Animals that feed on organisms that have died and decomposed into organic matter(detritus)
detritus
decomposed organic matter
Productivity
The rate at which organic matter is created by producers
Gross primary productivity
The amount of energy converted to chemical energy by photosynthesis per unit time in an ecosystem
NEt primary productivity
The gross primary productivity minus the energy used by the producers for respiration
Biological magnification
Organisms occupying higher trophic levels have greater concentration of accumulated toxins stored in their bodies
Primary ecological succession
Rebuilding of ecosystem in a lifeless area where soil has been removed
What is the essential and dominant characteristic of primary ecological succesion?
soil building
Eutrophication
- Disruption of freshwater ecosystems
- Runoff from sewage and manure increase nutrients in lakes and cause excessive growth
- Organic material accumulates on the bottom, reduces the depth
- Detritivores use up oxygen as they decompose organic matter
Acid Rain
- Caused by pollutants in the air from combustion of fossil fuels
- Nitrogen and sulfur pollutants cause pH of rain be less than 5.6
Greenhouse effect
- global warming
- Burning of fossil fuels caused the concentrations of CO2 in the air to increase
- CO2 and water vapor absorb infrared radiation reflecting off Earth, and temp rise
Chlorofluorocarbons
Chemicals used for refrigerants and aerosol cans
Depletion of Ozone Layer
- Accumulation of chlorofluorocarbons formed a hold in the ozone layer
- more ultraviolet light reach Earth, increase of skin cancer
Decomposer
-absorb most breakdown products and recycle nutrients back to the soil to nourish plants
Diatoms
Photosynthetic protists in the ocean
Phytoplankton
algae and photosynthetic bacteria in aquatic environments
Primary ecological succession
Rebuilding of ecosystem in a lifeless area where soil has been removed
What is the essential and dominant characteristic of primary ecological succesion?
soil building
Eutrophication
- Disruption of freshwater ecosystems
- Runoff from sewage and manure increase nutrients in lakes and cause excessive growth
- Organic material accumulates on the bottom, reduces the depth
- Detritivores use up oxygen as they decompose organic matter
Acid Rain
- Caused by pollutants in the air from combustion of fossil fuels
- Nitrogen and sulfur pollutants cause pH of rain be less than 5.6
Acid Rain
- Caused by pollutants in the air from combustion of fossil fuels
- Nitrogen and sulfur pollutants cause pH of rain be less than 5.6
Greenhouse effect
- global warming
- Burning of fossil fuels caused the concentrations of CO2 in the air to increase
- CO2 and water vapor absorb infrared radiation reflecting off Earth, and temp rise
Depletion of Ozone Layer
- Accumulation of chlorofluorocarbons formed a hold in the ozone layer
- more ultraviolet light reach Earth, increase of skin cancer
Decomposer
-absorb most breakdown products and recycle nutrients back to the soil to nourish plants
Diatoms
Photosynthetic protists in the ocean
Phytoplankton
algae and photosynthetic bacteria in aquatic eenvironments
Nitrogen-fixing bacteria
Live in the nodules in the roots of legumes and convert free nitrogen into ammonia
Nitrifying bacteria
Convert ammonia into nitrites and then into nitrates
Denitrifying bacteria
convert nitrates into free nitrogen
Decomposers
Bacteria that break down dead organic matter into ammonia
