R And K Strategies Pdf
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On r- and K-Selection
The concept of r and K strategems and their development during the evolution of organisms is certainly not new, although these particular terms to describe the process have been used for only a short period of time. As a matter of fact, the concept is implicit in some of the writings of Charles Darwin, among others. But, however old the basic theory is, there is presently a great deal of uncertainty as to how important these stratagems are in the functioning of organisms within ecological communities. Unable to display preview. Download preview PDF. Skip to main content.
On r- and K-Selection
Introduction : An organism's Darwinian fitness is calculated as the number of offspring it leaves behind that, themselves, survive to reproduce. In evolutionary terms, it is of no consequence if an organism is a fine, fully mature, physical specimen, or the dominant member of the herd, or even that an individual produces a lot of young but none of them survive. In the relay race of evolution, getting as many copies of your genes into the next generation as possible is the only goal. As you might imagine, there are many ways to be reproductively successful. One way is to become the dominant animal in a pack, and to monopolize mating opportunities, but another way is to be submissive and sneaky, mating with others when the dominant animal is not around to stop you.
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The meanings of r- and K-selection
This paper catalogues several different dichotomies that have all been termed r- and K-selection. The status of the concept of r- and K-selection is discussed and a more restricted usage of the terms is recommended. This is a preview of subscription content, access via your institution. Rent this article via DeepDyve.
In the equations describing growth of populations of organisms, r represents the slope of the line representing exponential growth. The letter K represents the carrying capacity of a habitat for members of a given sort of organism. The terms r-selection and K-selection have also been used by ecologists to describe the growth and reproductive strategies of various organisms.
The focus on either an increased quantity of offspring at the expense of individual parental investment of r-strategists, or on a reduced quantity of offspring with a corresponding increased parental investment of K -strategists, varies widely, seemingly to promote success in particular environments. The concepts of quantity or quality offspring are sometimes referred to as "cheap" or "expensive", a comment on the expendable nature of the offspring and parental commitment made. An unstable environment would encourage the parent to make many offspring, because the likelihood of all of the majority of them surviving to adulthood is slim.
Она тоже засмеялась. - Выслушай меня, Мидж. Направь мне официальный запрос. В понедельник я проверю твою машину. А пока сваливай-ка ты отсюда домой.
Руки на стол, - бросила она через плечо. - Когда я уйду, пожалуйста, никаких глупостей.
Переступив порог, она вовремя успела ухватиться за дверную раму и лишь благодаря этому удержалась на ногах: лестница исчезла, превратившись в искореженный раскаленный металл. Сьюзан в ужасе оглядела шифровалку, превратившуюся в море огня. Расплавленные остатки миллионов кремниевых чипов извергались из ТРАНСТЕКСТА подобно вулканической лаве, густой едкий дым поднимался кверху.