Abstract
In this paper we present an analysis of the hierarchical population structure of the mycophagous beetle Phalacrus substriatus. The analysis showed that P. substriatus is substructured at both hierarchical levels studied, among islands and among local populations within islands. The level of differentiation among local populations was about three times as high as among different islands (FPL = 0.043 and FLT = 0.013, respectively). This stands in marked contrast to the patterns expected, based on the dispersal of P. substriatus, as the average dispersal distance of individual beetles is less than a metre per generation. Several explanations are discussed which can explain the observed patterns. We also estimated the effective population size for both hierarchical levels. The results show that the Ne/N ratios are well below unity, both for local populations and for islands. The average Ne/N ratio for local populations was only 0.210 (geometric mean, 0.172), whereas for islands the observed Ne/N ratios ranged from 0.75 to 0.98. Population subdivision is expected to increase the global (island) effective population size under equilibrium situations. However, random extinctions and recolonizations can lead to significant reductions in the global effective population size. Because population turnover is a commonly occurring phenomenon in P. substriatus, we argue that this is, at least partly, responsible for the low Ne/N ratios observed in this species. The low effective population sizes, both for local populations and for islands, will result in rapid erosion of a large proportion of the genetic variation present. The present study thus highlights the need to take random processes, such as extinction-recolonization dynamics, into account when studying effects of spatial subdivision.
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Chesser, R K, Rhodes, O E, Sugg, D W, and Schnabel, A. 1993. Effective sizes for subdivided populations. Genetics, 135, 1221–1232.
Costa, J T, and Ross, K G. 1993. Seasonal decline in intracolony genetic relatedness in eastern tent caterpillars: implications for social evolution. Behav Ecol Sociobiol, 32, 47–54.
Costa, J T, and Ross, K G. 1994. Hierachical genetic structure and gene flow in macrogeographic populations of the Eastern tent caterpillar (Malacosoma americanum). Evolution, 48, 1158–1167.
Crow, J F, and Kimura, M. 1970. An Introduction to Population Genetics Theory. Harper & Row, New York.
Ericson, L. 1981. Aspects of the shore vegetation of the Gulf of Bothnia. Wahlenbergia, 7, 45–60.
Frankham, R. 1995. Effective population size/adult population size ratios in wildlife: a review. Genet Res, 66, 95–107.
Goudet, J. 1993. The genetics of geographically structured populations. Ph.D. Thesis, University of Wales, Bangor.
Goudet, J. 1995. FSTAT v1.2. A computer program to calculate F-statistics. J Hered, 86, 485–486.
Ingvarsson, P K, Olsson, K, and Ericson, L. 1997. Extinction-recolonization dynamics in the mycophagous beetle Phalacrus substriatus. Evolution, 51, 187–195.
Johannesen, J, and Loeschcke, V. 1996. A hierarchical analysis of genetic structure and variability in patchily distributed coexisting Chiastochta species (Diptera: Anthomyiidae). Heredity, 76, 437–448.
Kirby, G C. 1975. Heterozygote frequencies in small subpopulations. Theor Pop Biol, 8, 31–48.
Kontkanen, P. 1936. On the biology of Phalacrus substriatus. Ann Entomol Fenn, 2, 64–67.
Lacy, R C. 1987. Loss of genetic diversity from managed populations: interacting effects of drift, mutation, immigration, selection and population subdivision. Conserv Biol, 1, 143–158.
McCauley, D E. 1991. Genetic consequences of local population extinction and recolonization. Trends Ecol Evol, 6, 5–8.
McCauley, D E, and Eanes, W F. 1987. Hierarchical population structure analysis of the milkweed beetle, Tetraopes tetraophthalmus (Forster). Heredity, 58, 193–201.
Nei, M, and Tajima, F. 1981. Genetic drift and estimation of effective population size. Genetics, 98, 625–640.
Nichols, R A, and Hewitt, G M. 1994. The genetic consequences of long distance dispersal during colonization. Heredity, 72, 312–317.
Nunney, L. 1995. Measuring the ratio of effective population size to adult numbers using genetic and ecological data. Evolution, 49, 389–392.
Palmén, E. 1944. Die anemohydrochore Ausbreitung der Insekten als Zoogeographischer Faktor. Ann Zool Bot Fenn, (Vanamo), 10, 1–259.
Roderick, G K. 1996. Geographie structure of insect populations: gene flow, phylogeography, and their uses. Ann Rev Ent, 41, 325–352.
Sas Institute Inc. 1990. SAS/STAT User's Guide. Cary. NC.
Slatkin, M. 1977. Gene flow and genetic drift in a species subject to frequent local extinctions. Theor Pop Biol, 12, 253–262.
Slatkin, M. 1985. Gene flow in natural populations. Ann Rev Ecol Syst, 16, 393–430.
Slatkin, M. 1987. Gene flow and the geographic structure of natural populations. Science, 236, 787–792.
Slatkin, M, and Voelm, L. 1991. F ST in a hierarchical island model. Genetics, 127, 627–629.
Steiner, W E J. 1984. A review of the biology of Phalacrid beetles (Coleoptera). In: Wheeler, Q. and Blackwell, M. (eds) Fungus-Insect Relationships Perspectives in Ecology and Evolution, pp. 424–445. Columbia University Press, New York.
Unruh, T R. 1990. Genetic structure among 18 West Coast Pear psylla populations: implications for the evolution of resistance. Am Entomol, 36, 37–43.
Wade, M J, and McCauley, D E. 1988. Extinction and recolonization: their effects on the genetic differentiation of local populations. Evolution, 42, 995–1005.
Waples, R S. 1989. A generalized approach for estimating effective population size from temporal changes in allele frequency. Genetics, 121, 379–391.
Weir, B S. 1990. Genetic Data Analysis. Sinauer Associates, Sunderland. MA.
Weir, B S, and Cockerham, C C. 1984. Estimating F-statistics for the analysis of population structure. Evolution, 38, 1358–1370.
Whitlock, M C. 1992. Temporal fluctuations in demographic parameters and the genetic variance among populations. Evolution, 46, 608–615.
Whitlock, M C, and Barton, N H. 1997. The effective size of a subdivided population. Genetics, in press.
Whitlock, M C, and McCauley, D E. 1990. Some population genetic consequences of colony formation and extinction: genetic correlations within founding groups. Evolution, 44, 1717–1724.
Wright, S. 1943. Isolation by distance. Genetics, 28, 114–138.
Wright, S. 1951. The genetical structure of populations. Ann Eugen, 15, 323–354.
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Ingvarsson, P., Olsson, K. Hierarchical genetic structure and effective population sizes in Phalacrus substriatus. Heredity 79, 153–161 (1997). https://doi.org/10.1038/hdy.1997.138
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DOI: https://doi.org/10.1038/hdy.1997.138