Surprising new research differs completely from conventional thought and shows nature follows a mathematical "pwer-scaling law" showing preadator popultaions not grow at the same rate as prey populations, and which applies to all ecosystems

Surprising new research differs completely from conventional thought and shows nature follows a mathematical "pwer-scaling law" showing preadator popultaions not grow at the same rate as prey populations, and which applies to all ecosystems
Photo Credit: Radu Sigheti/Reuters)

Predators, prey, and the mathematics of nature

Share

Science has long presumed, and taught, that when the numbers of prey increase, the number of predators increase in a linear relationship.

New research says that’s not actually the case at all, that a doubling of prey does not result in a doubling of predators. Ian Hatton led the study for his PhD in biology at McGill University in Montreal.

Listen
Ian Hatton (PhD) is lead author of the study showin a new mathematical relationship between predators and prey throughout nature
Ian Hatton (PhD) is lead author of the study showin a new mathematical relationship between predators and prey throughout nature © supplied

Hatton is the lead-author of the research published this week in Science as, “The predator-prey power law: Biomass scaling across terrestrial and aquatic biomes

In statistics,  a “Power-scaling law” is a functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, where regardless of the initial size of the quantities, one varies as a power of the other.

What the researchers found was surprising and differs from long-held beliefs: in relative terms, the ratio of predators to prey declines as the number of prey increase.

Additionally, the study found that this concept may be a fundamental aspect of nature.

Researchers from McGill, and universities in Guelph and Waterloo in Ontario, and in Vancouver, B.C., calculated the biomass (weight) of prey mammals and predators in different locations in Africa. These included for example lions, cheetahs, hyenas as predators, and zebras, antelope, wildebeest etc as prey.

They found that in a given environment, as the biomass of prey increased- total kilograms of prey available- the biomass of predators in relation to that, decreased in a predictable mathematic function.

A lion feeds at Tanzania's Serengeti National Park. The researchers think one of the reasons predator populations don't grow as quickly as their prey is because they mainly eat young animals, and prey animals breed more slowly in more crowded conditions.
A lion feeds at Tanzania’s Serengeti National Park. The researchers think one of the reasons predator populations don’t grow as quickly as their prey is because they mainly eat young animals, and prey animals breed more slowly in more crowded conditions. © Noor Khamis/Reuters

Speaking to Emily Chung of the CBC Hatton cited the example of  the Kalahari where there are about 200kg of prey (buffalo, impala, etc) per square kilometre and about 4 kilograms of lion, hyena etc.   The lush Ngorongoro crater has roughly 100 times the amount of prey, at 20,000kg /km2 but only a little over 27 times the predators in the same are, or 110kg/km2.

The research also involved examination of some 1,000 other studies in 1,500 locations world-wide and found the same concept applied to aquatic ecosystems, and to plants and herbivores (which could be classed as predators of plants)

Hatton speculates that this surprising relationship may be due to another aspect of nature. Production (breeding) is reduced in crowded conditions.  Thus there are fewer young prey for  predator mammals which concentrate on the young or old as the breeding stock tends to be faster and fitter and harder to catch says Hatton. The same concept applies to plants and fish. Plant reproduction is lessened in crowded environments and for predators (herbivores) the younger, more tender plants are sought, and young, small fish are easier to catch and swallow.

The large-scale mathematical predictability of ecosystem productivity seems to be fundamental.

Hatton says this seems to indicate that many of the world’s natural systems have mathematical underpinnings and are not chaotic and random, or at least not as chaotic and random as might be believed.

Share
Tagged with: , , , , , , , , , , ,
Posted in Environment, International, Internet, Science and Technology

Do you want to report an error or a typo? Click here!

@*@ Comments

Leave a Reply

Your email address will not be published. Required fields are marked *

 characters available

Note: By submitting your comments, you acknowledge that Radio Canada International has the right to reproduce, broadcast and publicize those comments or any part thereof in any manner whatsoever. Radio Canada International does not endorse any of the views posted. Your comments will be pre-moderated and published if they meet netiquette guidelines.

Netiquette »

When you express your personal opinion in an online forum, you must be as courteous as if you were speaking with someone face-to-face. Insults and personal attacks will not be tolerated. To disagree with an opinion, an idea or an event is one thing, but to show disrespect for other people is quite another. Great minds don’t always think alike—and that’s precisely what makes online dialogue so interesting and valuable.

Netiquette is the set of rules of conduct governing how you should behave when communicating via the Internet. Before you post a message to a blog or forum, it’s important to read and understand these rules. Otherwise, you may be banned from posting.

  1. RCInet.ca’s online forums are not anonymous. Users must register, and give their full name and place of residence, which are displayed alongside each of their comments. RCInet.ca reserves the right not to publish comments if there is any doubt as to the identity of their author.
  2. Assuming the identity of another person with intent to mislead or cause harm is a serious infraction that may result in the offender being banned.
  3. RCInet.ca’s online forums are open to everyone, without regard to age, ethnic origin, religion, gender or sexual orientation.
  4. Comments that are defamatory, hateful, racist, xenophobic, sexist, or that disparage an ethnic origin, religious affiliation or age group will not be published.
  5. In online speak, writing in ALL CAPS is considered yelling, and may be interpreted as aggressive behaviour, which is unpleasant for the people reading. Any message containing one or more words in all caps (except for initialisms and acronyms) will be rejected, as will any message containing one or more words in bold, italic or underlined characters.
  6. Use of vulgar, obscene or objectionable language is prohibited. Forums are public places and your comments could offend some users. People who use inappropriate language will be banned.
  7. Mutual respect is essential among users. Insulting, threatening or harassing another user is prohibited. You can express your disagreement with an idea without attacking anyone.
  8. Exchanging arguments and opposing views is a key component of healthy debate, but it should not turn into a dialogue or private discussion between two users who address each other without regard for the other participants. Messages of this type will not be posted.
  9. Radio Canada International publishes contents in five languages. The language used in the forums has to be the same as the contents we publish. The usage of other languages, with the exception of some words, is forbidden. Messages that are off-topic will not be published.
  10. Making repetitive posts disrupts the flow of discussions and will not be tolerated.
  11. Adding images or any other type of file to comments is forbidden. Including hyperlinks to other websites is allowed, as long as they comply with netiquette. Radio Canada International  is in no way responsible for the content of such sites, however.
  12. Copying and pasting text written by someone else, even if you credit the author, is unacceptable if that text makes up the majority of your comment.
  13. Posting any type of advertising or call to action, in any form, to Radio Canada International  forums is prohibited.
  14. All comments and other types of content are moderated before publication. Radio Canada International  reserves the right to refuse any comment for publication.
  15. Radio Canada International  reserves the right to close a forum at any time, without notice.
  16. Radio Canada International  reserves the right to amend this code of conduct (netiquette) at any time, without notice.
  17. By participating in its online forums, you allow Radio Canada International to publish your comments on the web for an indefinite time. This also implies that these messages will be indexed by Internet search engines.
  18. Radio Canada International has no obligation to remove your messages from the web if one day you request it. We invite you to carefully consider your comments and the consequences of their posting.

*