The Rise and Fall of the Canada Lynx and Snowshoe Hare | Britannica Blog
It is attributed to Wikipedia user. Colourwheel and the . example, the snowshoe hare and lynx have a year cycle Predator and prey populations The hare cycle is mainly driven by excess predation by the lynx, but other factors, such as. The lynx and snowshoe hare predator-prey system in the Kluane region of the Yukon, We evaluate 10 linear relationships between predator and prey The numerical response is defined here as the relationship between. The idea that a coupled system of predator and prey would cycle gained An analysis of the numbers of snowshoe hares, and one of their main predators, the lynx, Examples include camouflage in the peppered moth, and prey that are.
What counts as predation? A predator is an organism that consumes all or part of the body of another—living or recently killed—organism, which is its prey.
In the broad definition, however, the zebra is too! Nor does a predator necessarily have to kill its prey. Instead, as in a grazing cow or a bloodsucking mosquito, it may simply take a portion of the prey's body and leave it alive. Population dynamics of predators and prey Populations of predators and prey in a community are not always constant over time.
Predators and their prey
Instead, in many cases, they vary in cycles that appear to be related. The most frequently cited example of predator-prey dynamics is seen in the cycling of the lynx, a predator, and the snowshoe hare, its prey. Strikingly, this cycling can be seen in nearly year-old data based on the number of animal pelts recovered by trappers in North American forests.
The population cycles of lynx and hare repeat themselves approximately every 10 years, with the lynx population lagging one to two years behind the hare population.
The classic explanation is this: As hare numbers increase, there is more food available for the lynx, allowing the lynx population to increase as well. When the lynx population grows to a threshold level, however, it kills so many hares that the hare population begins to decline.
This is followed by a decline in the lynx population due to scarcity of food. When the lynx population is low, the hare population begins to increase—due, at least in part, to low predation pressure—starting the cycle anew. Today, ecologists no longer think that the cycling of the two populations is entirely controlled by predation. For instance, it appears that availability of plant foods eaten by the hares—which decreases when hares become too abundant, due to competition—may also be a factor in the cycle.
Predation & herbivory
Defense mechanisms against predation When we study a community, we must consider the evolutionary forces that have acted—and continue to act! Species are not static but, rather, change over generations and can adapt to their environment through natural selection. Predator and prey species both have adaptations—beneficial features arising by natural selection—that help them perform better in their role. For instance, prey species have defense adaptations that help them escape predation.
These defenses may be mechanical, chemical, physical, or behavioral. Mechanical defenses, such as the presence of thorns on plants or the hard shell on turtles, discourage animal predation and herbivory by causing physical pain to the predator or by physically preventing the predator from being able to eat the prey. Chemical defenses are produced by many animals as well as plants, such as the foxglove, which is extremely toxic when eaten.
The millipede in the lower panel below has both chemical and mechanical defenses: Many species use their body shape and coloration to avoid being detected by predators. For instance, the crab spider has the coloration and body shape of a flower petal, which makes it very hard to see when it's standing still against the background of a real flower.
Can you even see it in the picture below? It took me a minute!
- Predator-prey interdependence
Snowshoe hares experience changes in population density in cycles spanning periods of about 8 to 11 years. During a cycle, their density may increase by as much as fold and then drop precipitously. It was once thought that the rapid declines were mainly the result of predation by lynx, but studies of snowshoe hare populations in places where lynx are not very abundant or are absent altogether—places such as Jacquot Island in southwestern Yukon and Prince Edward Island in eastern Canada—revealed that island snowshoe hares, like their mainland counterparts, also experience cyclic fluctuations.
Predator-prey cycles (video) | Ecology | Khan Academy
A snowshoe hare displaying its brown-colored summer coat. In The Conservation of the Wild Life of CanadaHewitt graphed the data from the records for a period extending from into the first decades of the s. His graphs emphasized the close relationship in population density between snowshoe hares and Canada lynx. Proposed causes have ranged from disease to predation to constraints in food supply.
The most significant factor driving fluctuations in snowshoe hare populations, however, appears to be simply exposure to stress, whether in the form of predation, disease, or scarcity of food. A report published in in the Journal of Animal Ecology detailed the results of a natural monitoring study paired with an experimental study testing the effects of stress on snowshoe hare reproduction.
The results revealed that female snowshoe hares have a strong adaptive response to stress. Both the pregnant females used in the experiment and the pregnant females sampled in the wild, which were in the midst of a population decline, were found to produce high levels of the hormone cortisola substance produced by animals under stress.