File Name: r and k strategies .zip
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.
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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. In contrast, more stable environments allow parents to confidently invest in one offspring because they are more likely to survive to adulthood. Wilson in  based on their work on island biogeography ;  although the concept of the evolution of life history strategies has a longer history  see e.
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. Those organisms described as r-strategists typically live in unstable, unpredictable environments. Here the ability to reproduce rapidly exponentially is important.
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.
Превозмогая боль, он бежал через гардеробную. У алтаря кто-то кричал, за спиной у него слышались тяжелые шаги. Беккер толкнул двойную дверь и оказался в некотором подобии кабинета. Там было темно, но он разглядел дорогие восточные ковры и полированное красное дерево. На противоположной стене висело распятие в натуральную величину. Беккер остановился. Тупик.
The four mentioned strategies may represent a strong suggestion for the categorization of such organisms as r strategists (Parry ; Ortuño.
Мидж открыла жалюзи и посмотрела на горы, потом грустно вздохнула и перевела взгляд на шифровалку. Вид купола всегда приносил ей успокоение: он оказался маяком, посверкивающим в любой час суток. Но сегодня все было по-другому. Она поймала себя на мысли, что глаза ее смотрят в пустоту. Прижавшись лицом к стеклу, Мидж вдруг почувствовала страх - безотчетный, как в раннем детстве.
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