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What is a species?
A group of organisms sharing common characteristics that can be interbred to produce offspring that can interbreed.
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What are the limitations of the species concept?
- Doesn’t account for asexually reproducing organisms.
- Doesn’t classify species in extinct populations.
- Doesn’t identify whether isolated populations belong to the same species.
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What is environment?
The external surroundings that affect species’ survival and development.
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What are abiotic factors?
- Salinity (Non-living, physical factors)
- Temperature
- pH
- Sunlight
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What are biotic factors?
Organisms.
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What is a habitat?
The environment in which the species lives.
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What is a Niche?
Where, when and how a species lives, what it feeds on, how it interacts with its habitat and other organisms etc.
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A niche defines a species.
Species can have overlapping niches, which leads to increased competition, but not the same niche. A particular set of biotic and abiotic factors a population responds to.
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What is fundamental and realized niche?
- Fundamental niche is the full range of conditions in which a species can survive and reproduce.
- Realized Niche is the actual range of conditions. (limited by interactions with other species)
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Range of intolerance, physiological stress.
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What are biotic factors?
Predation, Symbiosis, Parasitism, Herbivory, Disease, Competition
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Predation
- An animal hunts and eats another animal, negative feedback cycle,
- Also kinda good for prey because it creates a superior breeding pool
- What is Herbivory?
- An area with a more abundant plant resource has a larger carrying capacity for the herbivore
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What are ectoparasites?
Lice, ticks, mites
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What are endoparasites?
Tapeworms etc.
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What are pathogens?
Things that create disease
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What is intraspecific and interspecific competition?
- Inter is between different species
- Intra is within a species
- When resources decrease intra increases, when niches overlap, inter increases.
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The stronger competitor will…
Reduce the carrying capacity for the other’s environment
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What is a population?
A group of organisms of the same species living in the same area at the same time.
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S population curve?
- Due to limited resources and limiting factors, the rate of growth slows down and fluctuates when the carrying capacity is reached. Has 4 phases:
- 1.Lag phase: a small number of indivudals colonize the area nad have a small number of offspring
- 2.Exponential growth phase: limiting factors are not restricting the rate of growth, no disease no predation, good temperature, good rainfall
- 3.Transitional phase: limiting factors begin to affect the population and increased competition, disease and predation limit the rate of growth
- 4.Stationary phase: population growth stabilizes and fluctuates due to abiotic and biotic factors.
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What is carrying capacity?
Maximum number of individuals of a species that can be sustained by an environment.
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What is the J population curve?
- Limiting factors do not restrict the rate of growth
- Usually with species with rapid reproduction and minimal parental care like insects and shit
- Populations tend to crash due to overused food resources, change in abiotic factors, disease etc.)
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What are limiting factors?
Factors that limit the distribution or number of a particular population.
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What are density dependent limiting factors?
Factors that are affected by the population size of the species (food, water supply, predation, disease)
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What are density independent limiting factors?
- Not related to population density
- Natural disasters
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What is a community?
Many species living together.
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What is an ecosystem?
A community and the physical environment it interacts with.
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What is a trophic level?
The position that an organism occupies in a food chain.
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What is an autotroph?
Typically plants or algae that produce their own food.
- What is the second law of thermodynamics?
- Energy and biomass decrease along the food chain due to loss to heat.
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What is bioaccumulation?
The buildup of nonbiodegradable pollutants within an organism or trophic level.
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What is biomagnification?
The increase in the concentration of nonbiodegradable pollutants along the food chain.
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What is the unit of storage:
g/m2 or j/m2
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Respiration/ photosynthesis equation:
6CO2+6H20=C6H12O6+6O2
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What is respiration?
Chemical energy to kinetic energy and heat.
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What is a storage?
Standing stock of energy or a mass at a specific point in time.
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What is a flow?
A flow of energy or mass over a period of time.
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Primary productivity:
The total biomass or energy gained by producers in a specific area in a specific amount of time.
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Secondary productivity:
The total biomass or energy gained by consumers in a specific area in a specifc amount of time.
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Net Primary productivity:
Just deduct respiration.
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Why do heterotrophs lose more energy than autotrohps?
- More complex systems
- hunting , moving
- Complex reproduction
- Maintaining body temperature
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How to calculate efficiency?
Gross production/ energy invested x 100
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What is Gross Secondary Production?
- Total gain in biomass gained by consumers through absorption in a specific amount of time in a specific area
- Food eaten- fecal loss
- NSP is respiration deducted.
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Why is fecal loss higher in herbivores?
Cellulose is harder to digest
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Decomposition is:
Transfer
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What is the albedo effect?
- Is the measure of reflectivity of a surface
- Higher albedo with ice and snow, lower with water
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Why is not all of sunlight energy is used?
- Reflection from clouds
- Absorption by clouds
- Reflection from the surface of the earth
- Absorption by atmospheric levels and dust
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Explain Pyramid of Numbers
- Number of each individual at each trophic level
- Good for comparing populations through time
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Explain Pyramid of Biomass:
- Biological mass of the standing stock at each trophic level at a specific point in time
- May be misleading due to seasonal change and is hard to measure with many assumptions but good for comparing seasons
- g/m2 or j/m2
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Explain Pyramid of Productivity:
- Flow of energy through each trophic level of a foodchain over a period of time
- Always pyramid due to second law of thermodynamics and directly comparable (no seasonal change shit)
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Give ecosystem example:
- Pine-pine borer-salamander-snake
- Phytoplankton-starfish-flatfish-harp seals
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Why are top carnivores vulnerable?
- Effected by all trophic levels
- Biomagnification and bioaccumulation
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What are the implications of a pyramid structure?
Limited food chain due to second law of thermodynamics
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Explain decomposers:
- Detrivores: larger organisms that break the leftovers into smaller pieces for future decomposition
- Saprotrophs: fungi and soil bacteria
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Explain different kinds of plants:
- Hydrophytes: water plants
- Mesophytes: normal plants
- Xerophytes: cacti and stuff that store water
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What is sustainable yield?
- The rate of increse in biomass thast can be exploited without depleteing the original stock or its potential for replenishment
- Equal or lower to their natural productivity
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What is maximum sustainable yield?
- The maximum of a given resource such that the stock does not decline over time.
- Equivalent to net primary or secondary production
- (born+immigrated)-(death+emmigrated)
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Productivity unit:
j/m2yr or g/m2yr
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What are the reasons for high net productivity in an ecosystem?
- Higher primary productivity leads to higher energy investment in all tropic layers of the ecosystem
- Efficient energy transfer results in more energy to use
- Both result in longer food chains which means higher productivity
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