Summary
Due to human activities, populations of many species have become small and isolated. In this situation they become subject to genetic drift and inbreeding, resulting in loss of genetic variation, an increase in homozygosity, and possibly a decrease in viability (inbreeding depression). This process, here referred to as genetic erosion, may significantly increase the extinction probability of populations or even species, and is therefore currently an important issue in conservation biology. The research presented here aimed to determine the occurrence, extent, and significance of genetic erosion in natural populations of Scabiosa columbaria and Salvia pratensis, two species that are considered endangered in The Netherlands.
We observed decreased levels of both allozyme variation and phenotypic variation in the smaller populations of both species, indicating the occurrence of substantial genetic drift. Experiments that compared outcrossed progeny to selfed progeny showed a severe reduction in fitness for many fitness components, while on the other hand crosses between different populations revealed substantial heterosis. This proved that in both species there is potentially sufficient genetic load to cause inbreeding depression when populations become small. In contrast to expectation, no correlation between population size and the level of inbreeding depression due to selfing was observed, suggesting that purging of genetic load had not (yet) occurred in the small populations. This most probably indicates that the small populations had become small only recently. To evaluate the possible future consequences of the observed amount of genetic load, data on inbreeding depression were integrated with demographic data and the environmental variance in transition models. These computer simulations showed that most populations, both small and large, have a high probability of becoming extinct in the near future, and also that inbreeding depression did significantly increase this extinction probability of populations, except of those populations that, due to the high environmental stochasticity, already had a very high extinction chance in the absence of inbreeding depression. Implications of the results for possible management measures and future research are discussed.
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References
Barrett, S. C. H. and Charlesworth, D. (1991) Effects of a change in the level of inbreeding on the genetic load. Nature 352: 522–524.
Barrett, S. C. H. and Kohn, J. R. (1991) Genetic and evolutionary consequences of small population size in plants: implications for conservation. In: Falk, D. A. and Holsinger, K. E. (eds), Genetics and conservation of rare plants. Oxford University Press, Oxford, pp. 3–30.
Bijlsma, R., Ouborg, N. J. and van Treuren, R. (1991) Genetic and phenotypic variation in relation to population size in two plant species: Salvia pratensis and Scabiosa columbaria. In: Seitz, A. and Loeschcke, V. (eds), Species conservation: a population-biological approach. Birkhäuser Verlag, Basel, pp. 89–101.
Caswell, H. (1989) Matrix population models. Sinauer, Sunderland, MA.
Charlesworth, D. and Charlesworth, B. (1987) Inbreeding depression and its evolutionary consequences. Annu. Rev. Ecol. Syst. 18: 237–268.
Dudash, M. R. (1990) Relative fitness of selfed and outcrossed progeny in a self-compatible, protandrous species, Sabatia angularis L. (Gentianaceae): a. comparison in three environments. Evolution 44: 1129–1139.
Falconer, D. S. (1981) Introduction to quantitative genetics. 2nd edition, Longman, London.
Falk, D. A. and Holsinger, K. E. (1991) Genetics and conservation of rare plants. Oxford University Press, Oxford.
Frankel, O. H. and Soulé, M. E. (1981) Conservation and evolution. Cambridge University Press, Cambridge.
Gilpin, M. E. and Soulé, M. E. (1986) Minimum viable populations: the process of species extinctions. In: Soulé, M. E. (ed.), Conservation biology: the science of scarcity and diversity. Sinauer, Sunderland, MA, pp. 13–34.
Koelewijn, H. P. (1993) On the genetics and ecology of sexual reproduction in Plantago coronopus. Ph.D. Thesis, University of Utrecht.
Lande, R. and Barrowclough, G. F. (1987) Effective population size, genetic variation, and their use in population management. In: Soulé, M. E. (ed.), Viable populations for conservation. Cambridge University Press, Cambridge, pp. 87–124.
Lande, R. and Orzack, S. H. (1988) Extinction dynamics of age-structured populations in a fluctuating environment. Proc. Natl. Acad. Sci. USA 85: 7418–7421.
Menges, E. S. (1991a) The application of minimum viable population theory to plants. In: Falk, D. A. and Holsinger, K. E. (eds), Genetics and conservation of rare plants. Oxford University Press, New York, pp. 45–61.
Menges, E. S. (1991b) Stochastic modelling of extinction in plant populations. In: Fiedler, P. L. and Jain, S. (eds), Conservation biology: the theory and practice of nature conservation, preservation and management. Chapman and Hall, London, pp. 253–275.
Mitton, J. B. and Grant, M. C. (1984) Associations among protein heterozygosity, growth rate, and developmental homeostasis. Annu. Rev. Ecol. Syst. 15: 479–499.
Nei, M. (1987) Molecular evolutionary genetics. Columbia University Press, New York.
Ouborg, N. J. (1993) On the relative contribution of genetic erosion to the chance of population extinction. Ph.D. Thesis, University of Utrecht.
Ouborg, N. J., van Treuren, R. and van Damme, J. M. M. (1991) The significance of genetic erosion in the process of extinction. II. Morphological variation and fitness components in populations of varying size of Salvia pratensis L. and Scabiosa columbaria L. Oecologia 86: 359–367.
Ralls, K., Ballou, J. D. and Templeton, A. R. (1988) Estimates of lethal equivalents and the cost of inbreeding in mammals. Cons. Biol. 2: 185–193.
Schenkeveld, A. J. and Verkaar, H. J. (1984) On the ecology of short-lived forbs in chalk grasslands. Ph.D. Thesis, State University of Utrecht.
Schonewald-Cox, C. S., Chambers, S. M., MacBryde, B. and Thomas, L. (1983) Genetics and conservation: a reference for managing wild animal and plant populations. Benjamin-Cummings, London.
Shaffer, M. L. (1981) Minimum population sizes for species conservation. Bioscience 31: 131–134.
Shaffer, M. L. (1987) Minimum viable populations: coping with uncertainty. In: Soulé, M. E. (ed.), Viable populations for conservation. Cambridge University Press, Cambridge, pp. 69–86.
Soulé, M. E. (1987) Viable populations for conservation. Cambridge University Press, Cambridge.
Templeton, A. R. (1986) Coadaptation and outcrossing depression. In: Soulé, M. E. (ed.), Conservation biology: the science of scarcity and diversity. Sinauer, Sunderland, MA, pp. 105–116.
van Treuren, R. (1993) The significance of genetic erosion for the extinction of locally endangered plant populations. Ph.D. Thesis, University of Groningen.
van Treuren, R., Bijlsma, R., van Delden, W. and Ouborg, N. J. (1991) The significance of genetic erosion in the process of extinction. 1. Genetic differentiation in Salvia pratensis and Scabiosa columbaria in relation to population size. Heredity 66: 181–189.
van Treuren, R., Bijlsma, R., Ouborg, N. J. and van Delden, W. (1993a) The effect of population size and plant density on outcrossing rates in locally endangered Salvia pratensis. Evolution 74 (4), in press.
van Treuren, R., Bijlsma, R., Ouborg, N. J. and van Delden, W. (1993b) The significance of genetic erosion in the process of extinction. III. Inbreeding depression and heterosis effects due to selfing and outcrossing in Scabiosa columbaria. Evolution ,74 (5), in press.
van Treuren, R., Bijlsma, R. J., Ouborg, N. J. and Kwak, M. M. (1994) Relationship between plant density, outcrossing rates and seed set in natural and experimental populations of Scabiosa columbaria. J. Evol. Biol. ,7 (3): 287–302.
Weeda, E. J., Van der Meijden, R. and Bakker, P. A. (1990) Floron-Rode Lijst 1990: rode lijst van de in Nederland verdwenen en bedreigde planten (Pteridophyta en Spermatophytd) over de periode 1.I.1980–1.I.1990. Gorteria 16: 2–26.
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Bijlsma, R., Ouborg, N.J., van Treuren, R. (1994). On genetic erosion and population extinction in plants: A case study in Scabiosa columbaria and Salvia pratensis . In: Loeschcke, V., Jain, S.K., Tomiuk, J. (eds) Conservation Genetics. EXS, vol 68. Birkhäuser, Basel. https://doi.org/10.1007/978-3-0348-8510-2_21
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DOI: https://doi.org/10.1007/978-3-0348-8510-2_21
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