C-S-R Triangle theory

Universal adaptive strategy theory (UAST) is an evolutionary theory developed by J. Philip Grime in collaboration with Simon Pierce describing the general limits to ecology and evolution based on the trade-off that organisms face when the resources they gain from the environment are allocated between either growth, maintenance or regeneration – known as the universal three-way trade-off.

A universal three-way trade-off produces adaptive strategies throughout the tree of life, with extreme strategies facilitating the survival of genes via: C (competitive), the survival of the individual using traits that maximize resource acquisition and resource control in consistently productive niches; S (stress-tolerant), individual survival via maintenance of metabolic performance in variable and unproductive niches; or R (ruderal), rapid gene propagation via rapid completion of the lifecycle and regeneration in niches where events are frequently lethal to the individual.

It is impossible for an organism to evolve a survival strategy in which all resources are devoted exclusively to one of these investment paths, but relatively extreme strategies exist, with a range of intermediates. The system can be represented by a triangle, with the three extreme possibilities at its vertices. The different species may be located at some particular point inside this triangle, accommodating a certain percentage of each of the three strategies.

It is possible to use multivariate statistics to determine the main trends in phenotypic variability in a range of organisms, which for various major animal groups (most prominently vertebrates), has been shown to have three main endpoints consistent with UAST.

UAST is a key part of the twin-filter model describing how species with similar overall strategies but divergent sets of minor traits coexist in ecological communities.

C-S-R Triangle theory is the application of UAST to plant biology. The three strategies are competitor, stress tolerator, and ruderal. These strategies each thrive best in a unique combination of either high or low intensities of stress and disturbance.

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