Molecular evolution and ecological stress at global, regional and local scales: The Israeli perspective

Abstract

The enigma of genetic diversity and genome organization and evolution in nature has been investigated in plants and animals at the Institute of Evolution, University of Haifa, Israel, during the period 1974–1997. The major problem investigated was how much of the genetic diversity at single and multilocus structures is adaptive, processed by natural selection, and contributes to differences in fitness? Genetic diversity was found in different degrees among and within the numerous species tested at both the protein and DNA levels. Its organization in nature, at all scales, global, regional, and local, is nonrandom, heavily structured, frequently displays parallel trends in unrelated taxa, is positively correlated with abiotic and biotic ecological diversity and environmental stress, and is negatively correlated with population size. These results are inconsistent with the predictions of the neutral theory of molecular evolution and appear to be primarily driven by natural selection. Critical laboratory experiments using marine organisms show that inorganic and organic pollutants cause fast differential mortality, indicating that allozyme genotypes are selected by the environment. Theoretically, spatial and temporal ecological variation are of prime importance in maintaining genetic diversity in natural populations, particularly in dynamically cycling environments that can generate complex supercycles, T-cycles and chaotic-like behavior. This mode of multilocus dynamics exceeds the potential for maintaining genetic polymorphism under ordinary selection models. It may represent a novel evolutionary mechanism increasing genetic polymorphism over long time periods. Likewise, the genetic interaction between multiple species can drive the evolution of genetic diversity in nature. Modern molecular ecological-genetics and computational techniques of biomolecular sequence comparisons through ecological-genomics could highlight the origin, maintenance, abundance, structure and function of genetic polymorphisms and comparative genome evolution in dynamically changing environments. Critical studies are needed to identify, measure, and estimate the kind, degree and stage of operation of the major evolutionary forces, natural selection, migration, mutation, recombination, and genetic drift. J. Exp. Zool. 282:95–119, 1998. © 1998 Wiley-Liss, Inc.