Systems in Ecology
What is an open system in ecology?
A system that exchanges both energy (like sunlight) and matter (like water, nutrients) with its surroundings.
What is a species?
A group of organisms that can interbreed to produce fertile offspring.
What does a J-curve represent?
Exponential population growth with unlimited resources.
Who are producers?
Organisms (e.g., plants) that make their own food via photosynthesis.
What shape is a pyramid of energy?
Always upright.
What is the difference between a storage and a flow?
Storage is where energy/matter accumulates (boxes); flows move energy/matter between storages (arrows).
What is a niche?
The full role a species plays in its environment, including its interactions with abiotic and biotic factors.
What is the S-curve and carrying capacity?
S-curve shows logistic growth; carrying capacity (K) is the maximum population the environment can sustain.
What is the role of decomposers?
They break down dead matter and recycle nutrients into the ecosystem.
What is the 10% rule?
Only about 10% of energy is transferred to the next trophic level; the rest is lost as heat.
In the carbon cycle, what process moves CO₂ from the atmosphere to plants?
Photosynthesis.
What is the difference between a fundamental and realized niche?
Fundamental is the potential role a species could have; realized is the actual role it plays due to competition or other limits.
Name two limiting factors of population growth.
Examples: food scarcity, predation, disease, space, waste accumulation.
What are the main consumer types and what do they eat?
Primary: herbivores (plants); Secondary: carnivores/omnivores (herbivores); Tertiary: eat secondary consumers.
What's the difference between bioaccumulation and biomagnification?
Bioaccumulation: toxin buildup in an individual; biomagnification: toxin levels increase up the food chain.
How does the systems approach help us understand ecosystems better?
It models how energy and matter interact dynamically through storages and flows.
How does competition influence a species' niche?
It restricts the species to a smaller realized niche by limiting access to resources.
What happened to the reindeer on St. Matthew Island?
With no predators and abundant food, their population grew rapidly, then crashed due to overgrazing and starvation.
How does energy move in a food web?
From producers to consumers across trophic levels, with energy lost as heat at each step.
Why can a pyramid of numbers be inverted?
A single producer (e.g., tree) can support many consumers like insects.
Describe how energy and matter are exchanged in ecosystems using an example from the carbon cycle.
CO₂ (matter) flows into plants via photosynthesis; energy from sunlight drives this process, and carbon returns via respiration or combustion.
Give an example of how abiotic and biotic factors shape a species' realized niche.
A frog may tolerate a wide range of humidity (abiotic), but predator presence (biotic) limits where it actually lives.
How do limiting factors prevent indefinite population growth?
They reduce survival or reproduction when resources become scarce or pressures (like disease) increase.
Define GPP, NPP, and NSP.
GPP = total energy captured by producers; NPP = GPP minus respiration; NSP = energy available to next trophic level after consumer metabolism.
Describe Minamata disease and its ecological lesson.
Mercury pollution led to bioaccumulation in fish and biomagnification in humans, causing severe neurological damage.