2.2 Communities and Ecosystems Flashcards
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.
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.
Apex predator
Top of the food chain. Nothing eats it.
Trophic Cascade
an ecological phenomenon triggered by the addition or removal of top predators, leading to significant changes in ecosystem structure and nutrient cycling.
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 ecosystems.
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.
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.
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.
Interdependence (food webs)
pecies in a food web rely on each other for survival and ecosystem stability.
Top down vs bottom up trophic control
Top-Down Control – Predators regulate lower trophic levels, influencing ecosystem structure.
Bottom-Up Control – Primary producers determine energy flow and population sizes above them.
Food chain vs Food web
Food Chain – A linear sequence showing energy flow from one organism to another.
Food Web – A complex network of interconnected food chains within an ecosystem.
Criticisms of food webs as a model
Lacks quantitative data – Does not show energy transfer efficiency or biomass distribution.
Ignores temporal changes – Does not account for seasonal or long-term shifts in populations.
Assumes fixed relationships – Overlooks species adaptability and changing diets.
