How Do Ecological Communities Change Over Time

Question

How do ecological communities change over time?
A) Interactions between and among species may cause changes in ecological communities over time.
B) Keystone species typically become the most common species within an ecological community.
C) Species richness typically declines as one species outcompetes all other species.
D) Ecological communities are defined at a given point in time; any change leads to reclassification of the community.

Accepted Answer

Interactions between and among species, such as competition, predation, and mutualism, can lead to changes in ecological communities over time. Species may shift their ranges, undergo population fluctuations, or evolve new traits in response to these interactions, causing shifts in community composition and ecosystem function.

Answer: D
 Ecological communities are not fixed entities, but are dynamic and subject to change over time. As environmental conditions shift, species may adapt or migrate, causing changes in community composition. However, the classification of an ecological community is typically based on a snapshot in time, and any significant change in community structure may require the community to be reclassified.

B and C are incorrect because they do not accurately reflect the general patterns of community change. While keystone species can have significant impacts on community structure, they do not necessarily become the most common species. Similarly, while one species may outcompete others in some cases, this does not always lead to a decline in species richness, as other factors may also come into play.