Why aren’t there more lions? (Photo : McGill University)
Scientists revealed an odd law of nature that keeps large predator populations low despite large numbers for prey on land or underwater, in any region on the planet. For example, even if there are plenty of prey in the natural environment of larger predators like lions to feed upon, the number of lions in a certain region still does not increase.
This pattern is also observed on huge animals that dwell under the oceans and even tiny sea creatures such as zooplankton that feed on phytoplankton.
Researchers reveal that when prey is abundant, it does not necessarily mean that there are more predators, after they did an in depth analysis of data from the last 50 years of plants and animals spanning 2,260 ecosystems located in 1,512 diverse regions around the world that includes grasslands, oceans, lakes and forests.
As opposed to predators that can rise in numbers in order to keep up with the abundance of prey, predator populations are still limited when prey reproduce in numbers. In dense settings, prey reproduced less than when there are fewer prey around which suggests that the demand for resources are off set to limit prey offspring.
According to author of the study, Ian Hatton from the McGill University, the scientific premise is that when there is a lot of prey, there would be more predators in relation to that. However, when researchers examined the numbers, they discovered that even in the lushest and richest ecosystems in any region of the world, the ratio of predators to prey is greatly lesser.
Hatton also noted that when there is denser predator populations, prey species significantly reproduce less offspring for every individual. When the prey species' reproduction rates become limited, predators in effect, become limited also.
According to co-author of the study, Kevin McCann from the department of integrated biology at Guelph University, researchers were surprised when they finally realized this unique pattern across all plant and animal ecosystems.
McCann adds that this predator and prey biomass ratios in different ecosystems show a remarkable and well-predicted simple mathematical formula called the power scaling law.
This power law observed in nature reveals there are always fewer top predators in ecosystems that are rich in resources compared to ecosystems that lack resources where this new understanding can provide more clues to predator prey dynamics to help conservationists protect endangered species.
This study is published in the journal, Science.
