The Effects of Inbreeding on Isolated Populations: Are Minimum Viable Population Sizes Predictable?

  • Robert C. Lacy


Management of nature reserves, of multiple-use lands, and of captive breeding programs requires knowledge of the minimum population sizes below which the combined effects of random genetic changes and demographic variation would likely result in extinction. One prerequisite to estimating such minimum viable population sizes is the determination of the effects of inbreeding on fitness. Two hypotheses make distinct predictions about the relative tolerance of populations to inbreeding: If inbreeding depression results primarily from the expression of deleterious recessive alleles, then selection would have removed most such genes from populations with long histories of inbreeding, and those populations would be resistant to further inbreeding impacts. If inbreeding depression occurs because of a general selective advantage of heterozygosity throughout the genome, then previously inbred populations would have reduced fitness presently and would fare no better under future inbreeding than would large and heterogeneous populations. We tested the hypothesis that small, isolated populations of Peromyscus mice would show less depression in fitness when inbred than would large, central populations. Remnant, insular populations had one-quarter to one-third the genie diversity of large, central populations. Although the populations varied greatly in the rate of loss of fitness (measured as infant viability) when experimentally inbred, the severity of inbreeding depression did not correlate with initial genie diversity of the stocks or, therefore, with the size and degree of insularity of the wild populations. Neither simple theory of inbreeding depression could account for the varied responses of the populations. It remains an important task for conservation biologists to discover phylogenetic, ecological, or genetic predictors of genetically minimum viable population sizes.


Inbreeding Depression Genetic Load Isolate Population Insular Population National Seashore 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Literature Cited

  1. Ballou, J. 1983. Calculating inbreeding coefficients from pedigrees. In Genetics and conservation: A reference for managing wild animal and plant populations, ed. C.M. Schonewald-Cox, S.M. Chambers, B. MacBryde, and W.L. Thomas, 509–20. Menlo Park, Calif.: Benjamin/Cummings.Google Scholar
  2. Brewer, B.A. 1988. An investigation of protein electrophoresis as a predictor of inbreeding depression in captive populations of Peromyscus. In Dissertation Abstracts International 49: 5131. Cornell University, Ithaca, New York.Google Scholar
  3. Brewer, B.A., Lacy, R.C., Foster, M.L., Alaks, G. 1990. Inbreeding depression in insular and central populations of Peromyscus mice. J. Heredity 81: 257–66.Google Scholar
  4. Bulger, J., Hamilton, W.J. III. 1988. Inbreeding and reproductive success in a natural chacma baboon, Papio cynocephalus ursinus, population. Anim. Behav. 36: 574–78.CrossRefGoogle Scholar
  5. Connor, J.L., Bellucci, M.J. 1979. Natural selection resisting inbreeding depression in captive wild housemice (Mus musculus). Evolution 33: 929–40.CrossRefGoogle Scholar
  6. Conway, W.G. 1986. The practical difficulties and financial implications of endangered species breeding programs. Int. Zoo Yearbook 24 /25: 210–19.CrossRefGoogle Scholar
  7. Darwin, C. 1868. The variation of animals and plants under domestication. London: John Murray.Google Scholar
  8. Falconer, D.S. 1981. Introduction to quantitative genetics. New York: Longman.Google Scholar
  9. Garten, C.T., Jr. 1976. Relationships between aggressive behavior and genie heterozygosity in the oldfield mouse, Peromyscus polionotus. Evolution 30: 59–72.CrossRefGoogle Scholar
  10. Gilpin, M.E., Soulé, M.E. 1986. Minimum viable populations: Processes of species extinction. In Conservation biology: The science of scarcity and diversity, ed. M.E. Soule, 19–34. Sunderland, Mass.: Sinauer.Google Scholar
  11. Groves, C.R., Clark, T.W. 1986. Determining minimum population size for recovery of the black-footed ferret. Great Basin Nat. Memoirs 8: 150–159.Google Scholar
  12. Hamrick, J.L. 1983. The distribution of genetic variation within and among natural populations of plants. In Genetics and conservation: A reference for managing wild animal and plant populations, ed. C.M. Schonewald-Cox, S.M. Chambers, B. MacBryde, and L. Thomas, 335–48. Menlo Park, Calif.: Benjamin/Cummings.Google Scholar
  13. Humphrey, S.R., Barbour, D.B. 1981. Status and habitat of three subspecies of Peromyscus polionotus in Florida. J. Mamm. 62: 840–44.CrossRefGoogle Scholar
  14. Lacy, R.C. 1987. Loss of genetic diversity from managed populations: Interacting effects of drift, mutation, immigration, selection, and population subdivision. Cons. Biol. 1: 143–58.CrossRefGoogle Scholar
  15. Lacy, R.C., Clark, T.W. 1989. Genetic variability in black-footed ferret populations: Past, present, and future. In Conservation biology and the black- footed ferret, ed. U.S. Seal, E.T. Thome, M.A. Bogan, and S.H. Anderson, 83–103. New Haven: Yale University Press.Google Scholar
  16. Lerner, I.M. 1954. Genetic homeostasis. New York: J. Wiley and Sons.Google Scholar
  17. Lynch, C.B. 1977. Inbreeding effects upon animals derived from a wild population of Mus musculus. Evolution 31: 526–37.CrossRefGoogle Scholar
  18. Meyers, J. M. 1983. Status, microhabitat, and management recommendations for Peromyscus polionotus on Gulf Coast beaches Report. Atlanta: U.S. Fish and Wildlife Service.Google Scholar
  19. Mitton, J.B., Grant, M.C. 1984. Associations among protein heterozygosity, growth rate, and developmental homeostasis. Ann. Rev. Ecol. Syst. 15: 479–99.CrossRefGoogle Scholar
  20. Morton, N.E., Crow, J.F., Muller, H.J. 1956. An estimate of the mutational damage in man from data on consanguineous marriages. Proc. Nat. Acad. Sci. U.S.A. 42: 855–63.CrossRefGoogle Scholar
  21. O’Brien, S.J., Evermann, J.F. 1988. Interactive influence of infectious disease and genetic diversity in natural populations. Trends Ecol. Evol. 3: 254–59.CrossRefGoogle Scholar
  22. O’Brien, S.J., Roelke, M.E., Marker, L., Newman, A., Winkler, C.A., Meitzer, D., Colly, L., Evermann,J.F., Bush, M., Wildt, D.E. 1985. Genetic basis for species vulnerability in the cheetah. Science 227: 1428–34.Google Scholar
  23. O’Brien, S.J., Wildt, D.E., Goldman, D., Merril, C.R., Bush, M. 1983. The cheetah is depauperate in genetic variation. Science 221: 459–62.CrossRefGoogle Scholar
  24. Ralls, K., Ballou, J.D., Templeton, A. 1988. Estimates of lethal equivalents and the cost of inbreeding in mammals. Cons. Biol. 2: 185–93.CrossRefGoogle Scholar
  25. Rao, P.S.S., Inbaraj, S.G. 1980. Inbreeding effects on fetal growth and development. J. Med. Genet. 17: 27–33.CrossRefGoogle Scholar
  26. Reed, J.M., Doerr, P.D., Walters, J.R. 1988. Minimum viable population size of the red-cockaded woodpecker. J. Wildl. Manage. 52: 385–91.CrossRefGoogle Scholar
  27. Rowley, I., Russell, E., Brooker, M. 1986. Inbreeding: Benefits may outweigh costs. Anim. Behav. 34: 939–41.CrossRefGoogle Scholar
  28. Selander, R.K. 1983. Evolutionary consequences of inbreeding. In Genetics and conservation: A reference for managing wild animal and plant populations, ed. C.M. Schonewald-Cox, S.M. Chambers, B. MacBryde, and L. Thomas, 201–15. Menlo Park, Calif.: Benjamin/Cummings.Google Scholar
  29. Selander, R.K., Smith, M.H., Yang, S.Y., Johnson, W.E., Gentry, J.B. 1971. Biochemical polymorphism and systematics in the Genus Peromyscus. I. Variation in the old-field mouse (Peromyscus polionotus). Studies in Genetics. VI. Univ. Texas Publ. 7103: 49–90.Google Scholar
  30. Shaffer, M.L. 1981. Minimum population sizes for species conservation. Bio- Science 31: 131–34.Google Scholar
  31. Shaffer, M.L. 1983. Determining minimum viable population sizes for the grizzly bear. Int. Conf. Bear Res. Manage. 5: 133–39.Google Scholar
  32. Strong, L.C. 1978. Inbred mice in science. In Origins of inbred mice, ed. H.C. Morse, 45–67. New York: Academic Press.Google Scholar
  33. Templeton, A.R., Read, B. 1983. The elimination of inbreeding depression in a captive herd of Speke’s gazelle. In Genetics and conservation: A reference for managing wild animal and plant populations, ed. C.M. Schonewald-Cox, S.M. Chambers, B. MacBryde, and L. Thomas, 241–61. Menlo Park, Calif.: Benjamin/Cummings.Google Scholar
  34. U.S. Fish and Wildlife Service. 1987. Recovery plan for the Choctawhatchee, Perdido Key and Alabama Beach Mouse. Atlanta: U.S. Fish and Wildlife Service.Google Scholar
  35. van Noordwijk, A.J., Scharloo, W. 1981. Inbreeding in an island population of the great tit. Evolution 35: 674–88.CrossRefGoogle Scholar
  36. Wallace, B. 1970. Genetic load: Its biological and conceptual aspects. Englewood Cliffs, N.J.: Prentice-Hall.Google Scholar
  37. Wright, S. 1969. Evolution and the genetics of populations. Vol. 2. The theory of gene frequencies. Chicago: University of Chicago Press.Google Scholar
  38. Wright, S. 1977. Evolution and the genetics of populations. Vol. 3. Experimental results and evolutionary deductions. Chicago: University of Chicago Press.Google Scholar

Copyright information

© Routledge, Chapman & Hall, Inc. and Diane C. Fiedler 1992

Authors and Affiliations

  • Robert C. Lacy

There are no affiliations available

Personalised recommendations