Conservation Genetics

, Volume 2, Issue 4, pp 363–378 | Cite as

Captive breeding and the genetic fitness of natural populations

  • Michael Lynch
  • Martin O'Hely

Abstract

Many populations of endangered species are subject to recurrent introductions of individuals from an alternative setting where selection is either relaxed or in a direction opposite to that in the natural habitat. Such population structures, which are common to captive breeding and hatchery programs, can lead to a scenario in which alleles that are deleterious (and ordinarily keptat low levels) in the wild can rise to high frequencies and, in some cases, go to fixation. We outline how these genetic responses to supplementation candevelop to a large enough extent to impose a substantial risk of extinction for natural populations on time scales of relevance to conservation biology.The genetic supplementation load can be especially severe when a captive population that is largely closed to import makes a large contribution to the breeding pool of individuals in the wild, as these conditions insure thatthe productivity of the two-population system is dominated by captive breeders. However, a substantial supplementation load can even develop when the captive breeders are always derived from the wild, and in general, a severe restriction of gene flow into the natural population is required to reduce this load to an insignificant level. Domestication selection (adaptation to the captive environment) poses a particularly serious problem because it promotes fixations of alleles that are deleterious in nature, thereby resulting in a permanent load that cannot be purged once the supplementation program is truncated. Thus, our results suggest that the apparent short-term demographic advantages of a supplementation program can be quite deceiving. Unless the selective pressures of the captive environmentare closely managed to resemble those in the wild, long-term supplementation programs are expected to result in genetic transformations that can eventually lead to natural populations that are no longer capable of sustaining themselves.

captive breeding domestication selection extinction risk genetic load hatchery supplementation 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Adkison MD (1994) Application of Mathematical Modeling to Problems in Salmon Biology and Management. Ph. D. Dissertation, University of Washington, Seattle.Google Scholar
  2. Allendorf FW (1993) Delay of adaptation to captive breeding by equalizing family size. Conserv. Biol., 7, 416-419.Google Scholar
  3. Arnold SJ (1995) Monitoring quantitative genetic variation and evolution in captive populations. In: P opulation Management for Survival and Recovery (eds. Ballou JD,Gilpin M,Foose TJ), pp. 295-317. Columbia University Press, New York.Google Scholar
  4. Ballou JD,Gilpin M,Foose TJ, eds. (1995) Population Management for Survival and Recovery. Columbia University Press, New York.Google Scholar
  5. Bürger R,Hofbauer J (1994) Mutation load and mutation-selectionbalance in quantitative genetic traits. Journal of Mathematical Biology, 32, 193-218.Google Scholar
  6. Byrne A,Bjornn TC,McIntyre JD (1992) Modeling the response of native steelhead to hatchery supplementation programs in an Idaho river. North American Journal of Fisheries Management, 12, 62-78.Google Scholar
  7. Caballero A (1994) Developments in the prediction of effective population size. Heredity, 73, 657-679.Google Scholar
  8. Campton DE (1995) Genetic effects of hatchery fish on wild populations of Pacific salmon and steelhead: What do we really know? American Fisheries Society Symposium, 15, 337-353.Google Scholar
  9. Chesser RK,Rhodes EO,Sugg DW,Schnabel A (1993) Effective sizes for subdivided populations. Genetics, 135, 1221-1232.Google Scholar
  10. Crow JF (1993) Mutation, mean fitness, and genetic load. Oxford Surv. Evol. Biol., 9, 3-42.Google Scholar
  11. Crow JF,Kimura M (1970) An Introduction to Population Genetics Theory. Harper & Row, New York.Google Scholar
  12. Cuenco ML (1994) A model of an internally supplemented population. Transactions of the American Fisheries Society, 123, 277-288.Google Scholar
  13. Eyland EA (1971) Moran's island migration model. Genetics, 69, 399-403.Google Scholar
  14. Fleming IR,Gross MR (1993) Breeding success of hatchery and wild coho salmon (Oncorhynchus kisutch) in competition. Ecological Applications, 3, 230-245.Google Scholar
  15. Ford M (in press) The effects of selection during supportive breeding. Conserv. Biol. Google Scholar
  16. Frankham R,Loebel DA (1992) Modeling problems in conservation genetics using captive Drosophila populations: rapid genetic adaptation to captivity. Zoo Biology, 11, 333-342.Google Scholar
  17. Haldane JBS (1937) The effect of variation on fitness. American Naturalist, 71, 337-349.Google Scholar
  18. Holt RD,Gomulkiewicz R (1997) How does immigration influence local adaptation? A reexamination of a familiar paradigm. American Naturalist, 149, 563-572.Google Scholar
  19. Kapuscinski ARD,Lannan JE (1984) Application of a conceptual fitness model for managing Pacific salmon fisheries. Aquaculture, 43, 135-146.Google Scholar
  20. Kawecki TJ (1994) Accumulation of deleterious mutations and the evolutionary cost of being a generalist. American Naturalist, 144, 833-838.Google Scholar
  21. Kawecki TJ,Barton NH,Fry JD (1997) Mutational collapse of fitness in marginal habitats and the evolution of ecological specialization. J. Evol. Biol., 10, 407-429.Google Scholar
  22. Kimura M,Maruyama T,Crow JF (1963) Themutation load in small populations. Genetics, 48, 1303-1312.Google Scholar
  23. Kimura M,Ohta T (1969) The average number of generations until fixation of a mutant gene in a finite population. Genetics, 61, 763-771.Google Scholar
  24. Kirkpatrick M,Barton NH (1997) Evolution of a species' range. American Naturalist, 150, 1-23.Google Scholar
  25. Kohane MJ,Parsons PA (1988) Domestication: evolutionary change under stress. Evolutionary Biology, 23, 31-48.Google Scholar
  26. Lacy RC (1989) Analysis of founder representation in pedigrees: founder equivalents and founder genome equivalents. Zoo Biology, 8, 111-123.Google Scholar
  27. Larkin PA (1980) A perspective on population genetics and salmon management. Can. J. Fish. Aquatic Sci., 38, 1469-1475.Google Scholar
  28. Lande R,Barrowclough GF (1987) Effective population size, genetic variation, and their use in population management. In: Viable Populations for Conservation (ed. Soule ME), pp. 87-123. Cambridge University Press, UK.Google Scholar
  29. Lynch M,Blanchard J,Houle D,Kibota T,Schultz S,Vassilieva L,Willis J (1999) Spontaneous deleterious mutation. Evolution, 53, 645-663.Google Scholar
  30. Lynch M,Conery J,Bürger R (1995) Mutation accumulation and the extinction of small populations. American Naturalist, 146, 489-518.Google Scholar
  31. Olney PJS,Mace GM,Feistner ATC (1994) Creative Conservation Interactive Management of Wild and Captive Animals. Chapman and Hall, London, UK.Google Scholar
  32. Reisenbichler RR,McIntyre JD (1977) Genetic differences in growth and survival of juvenile hatchery and wild steelhead trout, Salmo gairdneri. J. Fish. Res. Bd. Canada 34, 123-128.Google Scholar
  33. Reisenbichler RR,Rubin SP (1999) Genetic changes from artificial propagation of Pacific salmon affect the productivity and viability of supplemented populations. ICES Journal of Marine Science, 56, 459-466.Google Scholar
  34. Ruzzante DE,Doyle RW (1993) Evolution of social behavior in a resource-rich structured environment: selection experiments with medaka (Oryzias latipes). Evolution, 47, 456-470.Google Scholar
  35. Ryman N,Laikre L (1991) Effects of supportive breeding on the genetically effective population size. Conservation Biology, 5, 325-329.Google Scholar
  36. Utter FM,Hindar K,Ryman N (1993) Genetic effects of aquaculture on natural salmonid populations. In: Salmon Aquaculture (eds. Heen K,Monahan RR,Utter F), pp. 144-165. Fishing News Books, Oxford, UK.Google Scholar
  37. Waples RS (1991) Genetic interactions between hatchery and wild salmonids: lessons from the Pacific northwest. Canadian Journal of Fisheries and Aquatic Sciences, 48, 124-133.Google Scholar
  38. Waples RS,Do C (1994) Genetic risk associated with supplementation of Pacific salmonids: captive broodstock programs. Canadian Journal of Fisheries and Aquatic Sciences, 51, 310-329.Google Scholar
  39. Whitlock MC,Barton NH (1997) The effective size of a subdivided population. Genetics, 146, 427-441.Google Scholar
  40. Wohlfarth GW (1993) Genetic management of natural fish populations. In: Genetic Conservation of Salmonid Fishes (eds. Cloud JG,Thorgaard GH), pp. 227-230. Plenum Press, New York.Google Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Michael Lynch
    • 1
  • Martin O'Hely
    • 1
  1. 1.Department of BiologyUniversity of OregonEugeneUSA

Personalised recommendations