2.2 Communities and Ecosystems Flashcards
Biomagnification
The concentration of toxic substances increases at each successive level of the food chain.
substances accumulate in tissues because they are not easily broken down or excreted. As a result, higher trophic levels (e.g., predators) tend to have higher concentrations.
Not to be confused with bioaccumulation
Bioaccumulation
the gradual accumulation of substances, such as pesticides or other chemicals, in an organism’s tissue.
Not to be confused with biomagnification
Apex predator
Top of the food chain. Nothing eats it.
Herbivore vs carnivore
Plant eater (primary consumer) vs meat eater (secondary consumer). An omnivore eats both.
Producer vs consumer
Producers are plants (they produce energy via photosynthesis). Consumers are animals (they produce energy from what they eat).
Autotroph vs heterotroph
Autotrophs make their own food (plants), whereas heterotrophs consume it (animals)
Primary consumer
Lowest animal link of the food chain (but second trophic level - after plants). Primary consumers are herbivores.
Same as a first-order consumer.
Secondary consumer
Eat herbivores (and are thus carnivores), but are the third trophic level when you take plants into account.
Same as a second-order consumer.
Tertiary consumer
Eats carnivores. Fourth trophic level.
Trophic
relates to the feeding habits or food relationship of different organisms in a food chain or ecosystem.
A trophic level represents part of a trophic niche.
Trophic cascade
A trophic cascade is an ecological phenomenon triggered by the addition or removal of top predators, leading to significant changes in ecosystem structure and nutrient cycling.
Keystone species
an organism that plays a crucial role in the way an ecosystem functions, with its impact on the environment and the diversity of life far greater than would be expected from its relative abundance or biomass.
Ecosystem engineer
a species that significantly modifies its environment, creating, altering, or maintaining habitat in ways that affect many other organisms within the ecosystem
Classic “textbook” example of an ecosystem engineer
Beaver.
Builds dams which support whole ecosystems and destroys others.
Classic “textbook” example of a keystone species
The sea otter.
Keep urchin populations down, which allows proliferation of kelp (which the sea urchin would otherwise eat. Take out the sea otter, and the kelp is stuffed.
Classic “textbook” example of a trophic cascade
Removal of wolves from Yellowstone…led to a proliferation of elk, overgrazing, decimation of trees for beavers to construct dams with, breaking down of aquatic ecosytems.
Pyramid of numbers
represents the count of organisms at each trophic level. It is quantified in units of individual organisms, showing the decreasing number of organisms as one moves from the base to the top of the pyramid.
The exception is when you have something like a tree at the bottom (a single organism) supporting a large number of herbivores (for example). Then the pyramid can have a basal inversion.
Pyramid of energy
illustrates the flow of energy through each trophic level, from producers at the base to apex predators at the top. It is measured in units of energy per area per time (e.g., kilocalories per square meter per year), indicating the decreasing availability of energy as one ascends the pyramid.
Pyramid of biomass
the total mass of living material at each trophic level in an ecosystem, with the largest mass at the base and decreasing mass at higher levels. It is measured in units of mass per area (e.g., grams per square meter)
