Final answer:
Cyclic population changes are fluctuations in species populations over time, influenced by environmental variations and predator-prey relationships. A well-known example is the cyclic changes between lynx and snowshoe hare populations. Population ecologists use mathematical models to understand and predict these fluctuations.
Step-by-step explanation:
Cyclic population changes refer to the predictable fluctuations in population sizes of certain species over time. These changes are often driven by environmental factors and species interactions, particularly predator-prey dynamics. For instance, fluctuations in the environment, such as changes in rainfall or availability of food sources, greatly influence the birth and death rates within populations. Additionally, small isolated populations may be greatly affected by catastrophic events, like wildfires or droughts, which can drastically reduce their numbers.
An iconic example of predator-prey dynamics is the relationship between the lynx and snowshoe hare populations in Northern Ontario. The population sizes of these species undergo cyclic fluctuations approximately every 10 years. As the hare population increases, it provides more food for the lynx, causing the lynx population to grow. However, once the lynx population reaches a high enough level, it leads to a dramatic decrease in the hare population due to predation. This, in turn, causes the lynx population to decline because of the reduced food availability. Eventually, the hare population begins to grow again due to lower predation pressure, and the cycle starts over.
Population ecologists use mathematical models to describe and predict these changes in population dynamics. However, researchers recognize that these models need to be continuously updated and refined in order to accurately represent complex ecological relationships and environmental influences on populations.