Status
Although r/K selection theory became widely used during the 1970s, it also began to attract more critical attention. In particular, a review by the ecologist Stephen C. Stearns drew attention to gaps in the theory, and to ambiguities in the interpretation of empirical data for testing it. In 1981 a review of the r/K selection literature by Parry, demonstrated that there was no agreement among researchers using the theory about the definition of r and K selection, which led him to question whether the assumption of a relation between reproductive expenditure and packaging of offspring was justified. A 1982 study by Templeton and Johnson, showed that in a population of Drosophila mercatorum under K selection the population actually produced a higher frequency of traits typically associated with r selection. Several other studies contradicting the predictions of r/K selection theory were also published between 1977 and 1994.
When Stearns reviewed the status of the theory in 1992 he noted that from 1977 to 1982 there was an average of 42 references to the theory per year in the BIOSIS literature search service, but from 1984 to 1989 the average dropped to 16 per year and continued to decline. He concluded that r/K theory was a once useful heuristic that no longer serves a purpose in life history theory.
More recently, the "Panarchy" theories of adaptive capacity and resilience promoted by C. S. Holling and Lance Gunderson, have revived interest in the theory, and use it as a way of integrating social systems, economics and ecology.
In 2002, Reznick and colleagues reviewed the controversy regarding r/K selection theory and wrote that: "The distinguishing feature of the r- and K-selection paradigm was the focus on density-dependent selection as the important agent of selection on organisms’ life histories. This paradigm was challenged as it became clear that other factors, such as age-specific mortality, could provide a more mechanistic causative link between an environment and an optimal life history (Wilbur et al. 1974; Stearns 1976, 1977). The r- and K-selection paradigm was replaced by new paradigm that focused on age-specific mortality (Stearns, 1976; Charlesworth, 1980). This new life-history paradigm has matured into one that uses age-structured models as a framework to incorporate many of the themes important to the r–K paradigm."
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