Understanding the differences between the CSR theory and its major alternative the R* theory has been a major goal in community ecology for many years. Plants that have adapted this strategy are often found colonizing recently disturbed land, and are often annuals. These species are fast-growing and rapidly complete their life cycles, and generally produce large amounts of seeds. Ruderals are plant species that prosper in situations of high intensity disturbance and low intensity stress. These species are often found in stressful environments such as alpine or arid habitats, deep shade, nutrient deficient soils, and areas of extreme pH levels. Stress tolerators respond to environmental stresses through physiological variability. Species that have adapted this strategy generally have slow growth rates, long-lived leaves, high rates of nutrient retention, and low phenotypic plasticity. Stress tolerators are plant species that live in areas of high intensity stress and low intensity disturbance. This last feature allows competitors to be highly flexible in morphology and adjust the allocation of resources throughout the various parts of the plant as needed over the course of the growing season. Competitors do this through a combination of favorable characteristics, including rapid growth rate, high productivity (growth in height, lateral spread, and root mass), and high capacity for phenotypic plasticity. These species are able to outcompete other plants by most efficiently tapping into available resources. These strategies each thrive best in a unique combination of either high or low intensities of stress and disturbance.Ĭompetitors are plant species that thrive in areas of low intensity stress (moisture deficit) and disturbance and excel in biological competition. The three strategies are competitor, stress tolerator, and ruderal. 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.Ĭ-S-R Triangle theory is the application of UAST to plant biology. 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. The different species may be located at some particular point inside this triangle, accommodating a certain percentage of each of the three strategies. The system can be represented by a triangle, with the three extreme possibilities at its vertices. 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. 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.
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