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Review by
Phil W. Hedrick (Dept of Biology, Arizona State University, Tempe,
AZ 85287, USA.
E-mail: philip.hedrick@asu.edu) in Trends in Ecology and Evolution 17:11
Many species have recently gone extinct or are in imminent danger of extinction because of environmental, economic, political and other forces. Most of the immediate biological changes that could help reverse this trend are ecological in nature, rather than genetical. However, genetics has played an important role in conservation biology since its inception, partly because of the emphasis placed on it by early researchers. There are many genetic applications that appear useful in identifying endangered organisms, and in estimating significant evolutionary and ecological parameters, and thereby assist in the long-term persistence of those species.
The authors suggest, and follow in the text, that laboratory research, theory (including computer simulations) and meta-analysis are the best approaches for understanding conservation genetics, a generally reasonable conclusion but one that I believe should be qualified. First, experiments using Drosophila (or other insect models) are of rather limited use in conservation genetics; I say this, given a former life dedicated to ‘pushing’ flies. Such laboratory experiments can often serve a useful heuristic purpose to illustrate evolutionary genetic principles or management options. However, it seems unlikely that laboratory experiments on insects with a history of very large population size will provide new insight into conservation of endangered species, most of which are vertebrates of small population size, have a history of declining numbers, might have important social and mating structures, and so on. Furthermore, if laboratory experiments give counterintuitive results, are those results relevant to endangered species or only to the model organism that is being used? Second, the value of theoretical research must also be viewed judiciously;
I say this having added significantly to the amount of theoretical literature.
Theoretical predictions should be viewed as only very general guidelines
to suggest differences among the impacts of various evolutionary factors
or management strategies. For example, the contention about the effective
population size that is necessary to retain evolutionary potential illustrates
the differing opinions about the application of both theoretical predictions
and appropriate input data [1,2]. For endangered species that might have
only one chance, the best approach is to err on the side on being conservative,
because things might turn out to be even worse than our most pessimistic
theoretical predictions. Finally, mete-analysis is an approach that needs
to be carefully evaluated and applied. In particular, ‘selective
reporting (e.g. the preferential publication of results that are statistically
significant, or consistent with theory or expectation) presents a challenge
to meta-analysis and seriously undermines the quest for generalizations’ [3],
a view that is relevant to many issues in conservation genetics. The authors make a strong statement suggesting that endangered species are unsuitable for experimentation, because of both practical and ethical considerations. In recent years, I have been involved with several endangered species in which experimentation has been possible (4,51, and which have given insights to the conservation of these species that would have otherwise been impossible. Furthermore, because the fates of many endangered species are so crucial, individuals are physically monitored [6], revealing genetic (and ecological) information that is not generally available from inferences made from laboratory experiments and/or theory. Conservation genetics is a new and applied discipline and is in need
of an introductory treatment; Introduction to Conservation Genetics fills
that gap. Many students are attracted to conservation genetics because
of their deep interest in conservation and the potential relevance of
modern genetic analysis. There are several instances in which conservation
genetics has been useful in the making of decisions concerning endangered species [7], but one should ask how it is different from evolutionary
genetics applied to endangered species. My feeling is that the management
of captive populations [8] is where conservation genetics makes a special
contribution. On this topic, the authors give a clear and thorough introduction
and one that is not available elsewhere at this level. References 2. Lynch, .M. and Lande, R. (1998) The critical effective size for a genetically secure population. Anim. Conserv. 1, 70-72 3. Palmer, A.R. (2000) Quasireplication and the contract of error: lessons from sex ratios, heritabilities and fluctuating asymmetry. Ann. Rev. Ecol. Syat. 31,441-480. 4. Arkush, K.D. et al. Resistance to three pathogens in the endangered winter-run Chincook salmon: effects of inbreeding and MHC genotypes. Can. J. Fish Aquat. Sci. (in press) 5. Sheffer, R. J. et al. (1999) Testing for inbreeding and outbreeding depression in the endangered Gila topminnow. Anim. Conserv. 2,121-129. 6. Land, D.E. and Lacy R.C. (2000) Introgression level achieved through Florida panther genetic restoration. Endangered Species Update 17.99-103. 7. Hedrick P.W. et al. (1997) Genetic evaluation of the three captive Mexican wolf lineages. Zoo Biology 16,47 69. 8. Ballou, J.D. et al, eds (1995) Population Management for Survival and Recovery, Columbia University Press
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