The Stability-Time Hypothesis: Reevaluation of the Data

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Abstract
The stability-time hypothesis of Sanders (1968) was proposed to account for new data which showed higher species richness of infaunal organisms in the deep sea than in similar shallow water habitats. It states that stressed and/or young environments will have fewer species than nonstressed and/or old environments. The mechanism suggested is that competitive interactions over evolutionary time in the stable environment of the deep sea have led to a large number of specialized species with narrow niches. Although the hypothesis is widely cited as originally proposed, it is tautological, and as such, is not falsifiable. The problem is that age and stress are not commensurate variables. For example, what pattern of species richness would the hypothesis predict in comparing communities from a young, nonstressed environment with communities from an old, stressed one? There are practical difficulties: age of a habitat or community is clearly difficult to measure, and stress is defined by its own effects. The data and the criteria upon which the hypothesis was based are reexamined. For the time-stability hypothesis to be valid the sampling scheme must have been similar in all regions, the number of samples must have been similar in all regions, the same taxonomic groups must have been compared, and all samples must have come from the same type of habitat. Violation of any or all of these would compromise the fit between the data and the hypothesis. [Data concerning the sampling of polychaete and bivalve populations are discussed.].