by David Galbraith
Andrew A. Chek, Kent A. Prior, David A. Galbraith, Stephen C. Lougheed. 2007. Herpetological Conservation 2:113-130 (Chapter 7)
Conservation genetics is principally concerned with 2 endeavours. The 1st approach uses genetic data to inform... more
Conservation genetics is principally concerned with 2 endeavours. The 1st approach uses genetic data to inform questions centred on relationships among individuals, populations, species or higher-level taxa. Such questions may relate to connectivity among populations (gene flow) and the effects of past or present fragmentation events, forensic applications (animal or plant derivative identification) or the evolutionary affinities among taxa (phylogeny). The 2nd approach emphasizes quantification of genetic diversity at various hierarchical levels, to understand immediate (inbreeding) or future (ability to adapt to changing environments) consequences of reduced genetic variation. Relatively few populations of Canada’s 43 species of reptiles have been investigated using genetic techniques, which is unfortunate, because theory suggests these peripheral populations can harbour unique genetic variants, or be substantially genetically diverged from core populations. Examples from Canada and elsewhere can be used to illustrate some of the main sorts of inquiry within the 2 areas outlined above. Genetic markers have been useful in clarifying the bounds and affinities of reptile taxa and the related task of assessing the value of the taxon. Genetic markers can offer indirect measures of gene flow/migration between populations, although these estimates are ideally anchored by ecological assessments (mark-recapture, radiotelemetry studies). Gene flow/migration is important in determining the proportion of genetic variation unique to a given population. Perhaps more practically, the extent to which populations are genetically connected determines the scale and geographic bounds of management units and the likelihood that a given population can recolonize an area where a neighbouring population has been extirpated. Small population size is correlated with the loss of genetic variation (for example, through founder effect or genetic drift), which may impair the future adaptive capacity of a population or species as a whole. Small population size also results in inbreeding, which can lead to the accumulation of deleterious alleles that reduce fitness and make the population decline further. Other applications of genetic markers include their use in determining the sex of individuals, important when the species is monomorphic, where the species is difficult to handle, or where only a sample of the individual is available. Genetic markers are also of use for investigations of mating systems. Which and how many males and females breed in a population may have important consequences for wild management, captive breeding, or reintroduction measures. Finally, genetic markers may be applied for forensic purposes: establishing the provenance or identity of an individual or part thereof. The relatively small proportion of Canadian reptiles genetically investigated is not a reflection of inadequate laboratory capacity or expertise. Our experience suggests there is a willing supply of both geneticists and students eager to carry out such work; financial resources are more often the limiting factor. Where resources are available, we suggest 3 areas of study that could contribute to Canadian reptile conservation: taxonomic studies, particularly where species are marked by geographic variation in morphology, or where the distribution of species is discontinuous or spans very different environments; studies of the conservation value of peripheral populations; and using genetic information and GIS tools to assess the effect of habitat disturbance on population connectivity over relatively short time scales.
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