Question

Describe the different population interactions with suitable examples.

Hint:

Score each interaction as plus, minus, or zero for each of the two species involved; that gives you all six named interactions.

Answer 1

Step 1: Understanding the Concept:
Population interactions describe how two different species living together in the same habitat affect each other's survival, growth, or reproduction. These interactions can help, harm, or have no effect on each species.

Step 2: Mutualism and commensalism.
In mutualism, both species benefit, for example lichens, where a fungus and an alga live together, the fungus giving protection and minerals while the alga provides food through photosynthesis. In commensalism, one species benefits while the other is unaffected, for example an orchid growing as an epiphyte on a large tree branch, gaining support without harming the tree.

Step 3: Predation and parasitism.
In predation, one organism (the predator) kills and eats another (the prey), for example a tiger hunting a deer. In parasitism, one organism (the parasite) lives in or on another (the host) and feeds off it, harming the host without immediately killing it, for example a tapeworm living in the human intestine.

Step 4: Competition and amensalism.
In competition, both species are harmed as they struggle over the same limited resource, for example two species of flour beetle competing for the same grain. In amensalism, one species is harmed while the other is unaffected, for example a large tree shading out and stunting small plants growing beneath it, without gaining anything itself from doing so.

Final Answer:
Population interactions include mutualism (both gain, as in lichens), commensalism (one gains, other unaffected, as with epiphytic orchids), predation and parasitism (one gains, other harmed), competition (both harmed), and amensalism (one harmed, other unaffected).