The r/K-selection theory was proposed by:
MacArthur and Wilson introduced the r/K selection framework while developing ideas about population growth and island biogeography. The labels come from the intrinsic growth rate, r, and carrying capacity, K, in the logistic model. Later ecologists refined or criticized the simple two-category scheme, but it remains useful as an introductory way to organize correlated life-history traits. Survivorship and reproductive schedules are connected through allocation. An organism has finite energy for growth, maintenance, defense, and reproduction; investment in one function constrains the others. Na
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12