3.1 Study Guide Flashcards
What is an organism’s ‘niche’? What is the difference between an organism’s fundamental niche and its realized niche?
An organism’s niche is all the biotic and abiotic resources it uses to survive. Fundamental niche refers to the maximum possible niche an organism could occupy, while realized niche refers to the actual niche it occupies in reality.
Define mutualism, commensalism, and parasitism and explain the differences between them. Give one example of each.
Mutualism, commensalism, and parasitism are all relationships between two organisms. In mutualism, both organisms benefit from the relationship; one example is the relationship between fig wasps and fig trees. In commensalism, only one organism is benefited instead of two while the other is unaffected; one example is the relationship between barnacles and whales. In parasitism, only one organism is benefited while the other is harmed instead of unaffected; one example is the relationship between deer ticks and deer.
What is the main distinction between predation and parasitism?
The main distinction between predation and parasitism is that, while both are interspecific relationships in which one organism benefits and the other is harmed, predation is short-term and one-time harm that usually ends in death for the harmed organism while parasitism is long-term and repeated harm that doesn’t always lead to death (at least not immediately).
In your opinion, is herbivory more similar to predation or parasitism? Explain your reasoning.
Possible answers:
Herbivory is more similar to predation because it happens as separate, individual events that harm different individuals almost every time.
Herbivory is more similar to parasitism because it does not kill the harmed organism, only taking part of it and possibly coming back for more later once it has regrown.
Explain the difference between facultative and obligatory symbiosis. What would happen to two species living in obligatory symbiosis if they were separated?
Symbiosis is a relationship between two organisms in which how they interact with each other benefits both of them. Facultative symbiosis is technically optional and is not required for the two organisms to survive, meaning they can be separated and be fine besides the lost benefits. Obligatory symbiosis, however, is required for the two organisms to survive, meaning they cannot be separated or they will both surely die.
Explain what endosymbiosis is and how it differs from standard symbiosis. How did the algae and protozoan from the video in class help each other to survive?
Endosymbiosis is an extreme form of symbiosis in which one species begins living inside of another and essentially becomes part of its body (though they still both help each other). In the video in class, the algae directed the protozoan toward sunlight and supplied it with sugars in return for protection inside its membrane (body).
What increases for two or more species when their niches overlap? What events often result from small and large niche overlap respectively?
When the niches of multiple species overlap, competition for resources increases for all individuals involved. When niches overlap slightly, the problem is often solved through niche partitioning, which is the natural adaptation of two organisms to have a distinction between their niches to reduce competition. If the niche overlap is too great for this to happen, however, the large increase in competition often leads to one or both species going extinct (or at least their populations involved).
Why does niche partitioning lead to increased biodiversity in an ecosystem? Give two examples of ways different species might partition their niches.
Because niche partitioning involves adaptation to using different resources and is also quite common, it makes it so species that partition their niches often do so through natural selection (individuals better suited to using different resources survive more often). Possible examples of ways species partition their niches include: Physical Space (moving to different areas), Food Sources, Time of Day When Foraging/Hunting, and Behavior Related to Nesting or Raising Offspring
Explain how neutralism is different from commensalism. State a case in which neutralism is portrayed.
Commensalism is an interspecific relationship in which one organism benefits and the other is unaffected by the interaction. Neutralism, however, is an interspecific “relationship” in which neither individual is affected at all. Neutralism happens all the time in nature; an example would be a bird and a deer in a forest which live in different spots and eat completely different plants.
There are many types of interspecies interactions around Earth. Most of them occur because they provide benefits for at least one of two organisms involved. Explain why an interspecies interaction in which one organism is hurt while the other is unaffected does not exist.
An interspecific interaction in which one organism is unaffected and the other harmed does not exist because neither individual would have any reason to stay in the interaction. Neither is benefited and one is actively harmed and would always attempt to escape the other. In Parasitism, Predation, and Herbivory, the only reason the harmed individual does not leave the interaction is because it can’t, either because it physically can’t move or because the benefited individual does not allow it. Without this drive of the benefited individual to sustain the interaction, the harmed individual would have no trouble leaving or, in the case of plants, growing somewhere else.
