Selection versus random drift: long–term polymorphism persistence in small populations (evidence and modelling)

Our data on a subterranean mammal, Spalax ehrenbergi , and other evidence, indicate that appreciable polymorphism can be preserved in small isolated populations consisting of several dozens of, or a hundred, individuals. Current theoretical models predict fast gene fixation in small panmictic populations without selection, mutation, or gene inflow. Using simple multilocus models, we demonstrate here that moderate stabilizing selection (with stable or fluctuating optimum) for traits controlled by additive genes could oppose random fixation in such isolates during thousands of generations. We also show that in selection–free models polymorphism persists only for a few hundred generations even under high mutation rates. Our multi-chromosome models challenge the hitchhiking hypothesis of polymorphism maintenance for many neutral loci due to close linkage with few selected loci.

[1]  G. Hartl,et al.  Maintenance of high levels of allelic variation in spite of a severe bottleneck in population size: the brown bear (Ursus arctos) in the Western Carpathians , 1994, Biodiversity & Conservation.

[2]  E. Nevo,et al.  CYCLICAL ENVIRONMENTAL CHANGES AS A FACTOR MAINTAINING GENETIC POLYMORPHISM. 2. DIPLOID SELECTION FOR AN ADDITIVE TRAIT , 1996, Evolution; international journal of organic evolution.

[3]  M. Rader,et al.  A computer model , 1996, IEEE Conference Record - Abstracts. 1996 IEEE International Conference on Plasma Science.

[4]  Gillespie,et al.  Development of Neutral and Nearly Neutral Theories , 1996, Theoretical population biology.

[5]  E. Nevo.  Mammalian evolution underground. The ecological-genetic-phenetic interfaces , 1995 .

[6]  A. Hastings,et al.  Dynamics of polygenic variability under stabilizing selection, recombination, and drift. , 1995, Genetical research.

[7]  Glyn W. Humphreys,et al.  Non-spatial extinction following lesions of the parietal lobe in humans , 1994, Nature.

[8]  Peter Arcese,et al.  Selection against inbred song sparrows during a natural population bottleneck , 1994, Nature.

[9]  E. Nevo,et al.  Chromosomal speciation and adaptive radiation of mole rats in Asia Minor correlated with increased ecological stress. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[10]  E. Nevo,et al.  Genetic polymorphisms in subterranean mammals (Spalax ehrenbergi superspecies) in the Near East revisited: patterns and theory , 1994, Heredity.

[11]  A. Hastings,et al.  Maintenance of multilocus variability under strong stabilizing selection , 1994, Journal of mathematical biology.

[12]  L. Nunney,et al.  Assessing minimum viable population size: Demography meets population genetics. , 1993, Trends in ecology & evolution.

[13]  E. H. Bryant,et al.  The effect of serial founder-flush cycles on quantitative genetic variation in the housefly , 1993, Heredity.

[14]  D. Coates.  Genetic consequences of a bottleneck and spatial genetic structure in the triggerplant Stylidium coroniforme (Stylidiaceae) , 1992, Heredity.

[15]  E. Nevo.  Evolutionary theory and processes of active speciation and adaptive radiation in subterranean mole rats, Spalax ehrenbergi superspecies, in Israel , 1991 .

[16]  N. Barton,et al.  Dynamics of polygenic characters under selection. , 1990 .

[17]  H. Carson.  Increased genetic variance after a population bottleneck. , 1990, Trends in ecology & evolution.

[18]  R. Bürger.  Linkage and the maintenance of heritable variation by mutation-selection balance. , 1989, Genetics.

[19]  R. Lande.  Genetics and demography in biological conservation. , 1988, Science.

[20]  W. G. Hill,et al.  Quantitative genetic variability maintained by mutation-stabilizing selection balance in finite populations. , 1988, Genetical research.

[21]  E. Nevo.  Genetic Diversity in Nature , 1988 .

[22]  R. Lande,et al.  Evolution of genetic variability in a spatially heterogeneous environment: effects of genotype-environment interaction. , 1987, Genetical research.

[23]  Aharon Horowitz,et al.  The late Pleistocene climate of Israël / Le climat au Pléistocene récent en Israël , 1986 .

[24]  P. Hedrick.  GENETIC POLYMORPHISM IN HETEROGENEOUS ENVIRONMENTS: A DECADE LATER , 1986 .

[25]  A. Bell,et al.  An experimental study of genetic drift for two quantitative traits in Tribolium , 1984 .

[26]  R. Ben-Shlomo,et al.  The Evolutionary Significance of Genetic Diversity: Ecological, Demographic and Life History Correlates , 1984 .

[27]  W. G. Hill,et al.  Population and quantitative genetics of many linked loci in finite populations , 1983, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[28]  W. G. Hill,et al.  Effects of linkage on response to directional selection from new mutations. , 1983, Genetical research.

[29]  Philip W. Hedrick,et al.  Genetic Hitchhiking: A New Factor in Evolution? , 1982 .

[30]  O. H. Frankel,et al.  Conservation and Evolution , 1983 .

[31]  John Maynard Smith,et al.  Polymorphism in a varied environment: how robust are the models? , 1980, Genetical research.

[32]  E. Nevo.  Adaptive Convergence and Divergence of Subterranean Mammals , 1979 .

[33]  R. Kaplan,et al.  Th. Dobzhansky, F. J. Ayala, G. L. Stebbins, and J. W. Valentine. Evolution. 572 S., 123 Zeichnungen. Schemata und Kurven. San Francisco 1977. H. W. Freeman & Co. Ltd. £ 18.60 , 1979 .

[34]  J H Gillespie,et al.  A general model to account for enzyme variation in natural populations. V. The SAS--CFF model. , 1978, Theoretical population biology.

[35]  E Nevo,et al.  Genetic variation in natural populations: patterns and theory. , 1978, Theoretical population biology.

[36]  P. Hedrick,et al.  Genetic Polymorphism in Heterogeneous Environments , 1976 .

[37]  J H Gillespie,et al.  A general model to account for enzyme variation in natural populations. , 1974, Genetics.

[38]  E. Nevo,et al.  GENETIC VARIATION, SELECTION AND SPECIATION IN THOMOMYS TALPOIDES POCKET GOPHERS , 1974, Evolution; international journal of organic evolution.

[39]  M. Kimura,et al.  An introduction to population genetics theory , 1971 .

[40]  R. Lewontin,et al.  Is the gene the unit of selection? , 1970, Genetics.

[41]  C. Wills,et al.  A computer model allowing maintenance of large amounts of genetic variability in mendelian populations. I. Assumptions and results for large populations. , 1970, Genetics.

[42]  J. Sved.  The stability of linked systems of loci with a small population size. , 1968, Genetics.

[43]  Sewall Wright,et al.  Factor interaction and linkage in evolution , 1965, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[44]  R. Lewontin,et al.  THE INTERACTION OF SELECTION AND LINKAGE. II. OPTIMUM MODELS. , 1964, Genetics.

[45]  R. Lewontin.  The Interaction of Selection and Linkage. I. General Considerations; Heterotic Models. , 1964, Genetics.

[46]  K. Kojima.  STABLE EQUILIBRIA FOR THE OPTIMUM MODEL. , 1959, Proceedings of the National Academy of Sciences of the United States of America.

[47]  S. Wright.  Evolution in mendelian populations , 1931 .