Appropriate and interesting applications of genetics to conservation:. Conservation genetics as a distinct discipline became prominent in the early s Schonewald-Cox et al. Nunney and Campbell reviewed viability analysis approaches that combine demographic and genetic perspectives. Caughley continued the debate with arguments for downplaying genetic factors, while Hedrick et al.
Haig and Hedrick reviewed molecular approaches to conservation. A psychologist magician? Frankham and Hedrick reviewed the general area of conservation genetics, and Amos and Balmford and Vernesi et al. A volume edited by Avise and Hamrick also contains a reasonably broad spectrum of views on the subject see the review of the book by Holsinger, A book on extinction Landweber and Dobson, contains other useful material.
Hedrick and Miller provide a useful overview of the genetic knowledge and tools needed. As with any goal-oriented endeavor, any approach to conservation genetics requires weighing costs against potential benefits. Genetics is simply one of many tools in the conservation arsenal -- it may be an appropriate tool in some contexts and not in others.
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Genetics vs. Others have argued more strongly that genetics is relatively unimportant because demographic and habitat factors are always the first cause of declines, and that genetic "problems" are a consequence not a cause. Several studies have shown that cheetahs exhibit very limited genetic variability. Cheetahs show little genetic variation among individuals and populations. Whether the low variation is crucial in a conservation context has been controversial.
Genetics as a demographic tool. If we accept the proposition that demography is more important than genetics in determining the fate of populations, we may nevertheless find that genetic tools are our best route to demographic understanding Milligan et al. Patterns of genetic variation contain a record of demographic forces and patterns such as fluctuating population size, sex ratio variation and migration.
Genealogical and coalescent approaches Hudson, , in particular, can help separate out the purely genetic processes such as mutation from the demographic processes such as population size variation that are likely to be of most interest to conservationists. Harvey and Steers provide examples of how sequence data can promote inferences about population history. One of the problems with most demographic analyses is that they represent a very short-term view -- a few years to a few generations. A sensitivity analysis from demographic data is necessarily based on present or very recent conditions.
Genetic data can provide a record of rare or long term trends that, in the extreme, make the current conditions irrelevant. Genetic data can also provide conservation-relevant information on mating system -- for example, the degree of reliance of a plant species on its pollinator high dependence for obligate outcrossers or the degree of polygyny in animal populations which in turn affects effective population size, N e. Genetic data are increasingly important in assessing the degree of connectedness between populations -- gene flow is critically important to the maintenance of genetic diversity and to the probability of persistence in metapopulations.
Mutational meltdown. Lynch et al. The idea here is that at very small population sizes, harmful mutations may be expressed more widely and have much stronger effects on fitness, leading to a downward spiral and ultimate extinction. The empirical evidence to date, however, is negative Gilligan et al. Gilligan et al. Inbreeding depression and genetic load. Inbreeding depression is a reduction in fitness experienced by individuals that have high homozygosity driven by the greater expression of moderately or highly deleterious recessive alleles Hedrick and Kalinowski, How important is inbreeding depression in natural populations?
In theory, individuals that are highly inbred such as those in very small, endangered populations that were recently large might be subject to inbreeding depression because higher homozygosity unmasks deleterious mutations. In practice, it is unclear exactly how and when inbreeding depression occurs in natural or captive populations Hedrick and Miller, ; Ralls and Meadows, ; Lacy et al. For example, small populations that have survived bottlenecks, or that have always had small N e , may largely purge the deleterious recessive alleles.
Inbreeding depression is therefore most likely in species with historically large population sizes -- in that case, masked deleterious alleles will severely impact any individuals that do inbreed following local or rapid bottlenecks. Skip to content Skip to search. Smith and Robert K. Language English View all editions Prev Next edition 2 of 4. Other Authors Smith, Thomas B. Thomas Bates Wayne, Robert K. Subjects Biologie de la conservation.
Moleculaire genetica. Genetica molecular e de microorganismos.
Conservation biology. Molecular genetics. Biodiversity conservation. Contents Machine derived contents note: 1.
An Overview of the Issues, Georgina M. Mace et al.
Approaches 2. Palumbi and C. Scott Baker 3. Karl 4. Riesberg 5. Tucker and Barbara L. Lundrigran 6. Leberg 7.
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Ricklefs 8. Girman Cann et al. Edwards and Wayne K. Potts Bruford et al.
Conservation genetics of endangered horse breeds
Morin and David S. Woodruff Analysis These techniques can provide information on long-term conservation of genetic diversity and expound demographic and ecological matters such as taxonomy. Another technique is using historic DNA for genetic analysis. Historic DNA is important because it allows geneticists to understand how species reacted to changes to conditions in the past. This is a key to understanding the reactions of similar species in the future. Techniques using historic DNA include looking at preserved remains found in museums and caves.
The problem with museums is that, historical perspectives are important because understanding how species reacted to changes in conditions in the past is a key to understanding reactions of similar species in the future. Another technique that relies on specific genetics of an individual is noninvasive monitoring, which uses extracted DNA from organic material that an individual leaves behind, such as a feather. Other more general techniques can be used to correct genetic factors that lead to extinction and risk of extinction. For example, when minimizing inbreeding and increasing genetic variation multiple steps can be taken.
Increasing heterozygosity through immigration, increasing the generational interval through cryopreservation or breeding from older animals, and increasing the effective population size through equalization of family size all helps minimize inbreeding and its effects. Inbreeding depression, loss of genetic diversity, and genetic adaptation to captivity are disadvantageous in the wild, and many of these issues can be dealt with through the aforementioned techniques aimed at increasing heterozygosity.
In addition creating a captive environment that closely resembles the wild and fragmenting the populations so there is less response to selection also help reduce adaptation to captivity.
- Polymorphism of Mhc genes: implications for conservation genetics of vertebrates;
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Solutions to minimize the factors that lead to extinction and risk of extinction often overlap because the factors themselves overlap. For example, deleterious mutations are added to populations through mutation, however the deleterious mutations conservation biologists are concerned with are ones that are brought about by inbreeding, because those are the ones that can be taken care of by reducing inbreeding.
Here the techniques to reduce inbreeding also help decrease the accumulation of deleterious mutations. These techniques have wide ranging applications. One application of these specific molecular techniques is in defining species and sub-species of salmonids. In Cutthroat Trout mtDNA and alloenzyme analysis, hybridization between native and non-native species was shown to be one of the major factors contributing to the decline in their populations.
This led to efforts to remove some hybridized populations so native populations could breed more readily. Cases like these impact everything from the economy of local fishermen to larger companies, such as timber. Specific molecular techniques led to a closer analysis of taxonomic relationships, which is one factor that can lead to extinctions if unclear.
New technology in conservation genetics has many implications for the future of conservation biology. At the molecular level, new technologies are advancing. Some of these techniques include the analysis of minisatellites and MHC. These effects then have consequences that reach even further.
Conservation of species has implications for humans in the economic, social, and political realms. From Wikipedia, the free encyclopedia.