DEEP-SEA ASTEROIDS: HIGH GENETIC VARIABILITY IN A STABLE ENVIRONMENT.

Abstract

The distribution of geinetic variability in deep-sea organisms is virtually unknown, although estimates of genetic variability in the deep-sea fauna are directly relevant to some hypotheses concerning adaptive strategies in stable and unstable environments. One hypothesis, advanced to account for the great species diversity observed in the deep-sea, argues that deep-sea populations are highly specialized and possess little genetic variability (Grassle, 1972). Another hypothesis, also predicting that deep-sea populations should have little genetic variability, has been advanced by Bretsky and Lorenz (1969, 1970) to account for the waves of extinctions registered in the paleontological record. This hypothesis proposes that organisms living in stable environments should be genetically depauperate. Since the deep-sea provides one of the most stable environments in the world, both hypotheses can be tested by examining the amount of genetic variation in deep-sea organisms. In the course of a broad survey of genetic variability in diverse marine environments we have studied the genetic variability of four species of deep-sea asteroids from the San Diego Trough at a depth of 1,244 meters. Allelic variation at 24 individual loci coding for enzymes and other soluble proteins has been studied using the techniques of starch gel electrophoresis.