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04/11/12 11:37 AM
Its use for species conservation is becoming urgent and increasingly feasibl

Genomics, an essential tool to the analyses of evolution

It will facilitate the direct analysies of functional genetic variation in endangered species

Technological progress in genomic are revolutionising  the analyses on evolutionary processes and on functional genetic variation in endangered species. The current genetical methodologies have important limitations and the novel genomic approaches promise to mitigate this bottleneck.


Technological progress in genomic are revolutionising  the analyses on evolutionary processes and on functional genetic variation in endangered species. The current genetical methodologies have important limitations and the novel genomic approaches promise to mitigate this bottleneck.

The vast majority of genetic studies of threatened species to date have been based on the application of a limited number of supposedly neutral molecular markers such as microsatellites, under the fundamental assumption that genetic variation for these markers can estimate the global variation of the genome and that this in turn will be highly correlated with the functional and potentially adaptive component of variation.

However, empirical evidence suggests a limited power of microsatellite markers to estimate global variation of the genome, and the dynamics of neutral and adaptive variation may differ substantially following a population bottleneck because of the possible differential contribution of selection and mutation. A more extensive assessment of global genomic variation and a direct evaluation of functional variation have been thus recognized as imperative tasks for conservation genetics.

 

The genome is a real map.
The genome is a real map.

Great promises

 

One of the great promises of a genomic approach in ecology and evolution is the possibility of identifying the molecular basis of life history, physiological and behavioural traits that are key to the interactions between organisms and their environment, an important prerequisite to better understand their evolutionary dynamics. Genomics will add great power and resolution to the analyses of demographic and evolutionary processes, based on neutral variation.

Firstly, genomic approaches should greatly enhance the power and resolution of the analysis of geographic patterns of variation, and of the demographic and evolutionary processes that have shaped them, by providing thousands of genetic markers, including insertion-deletion, copy-number, and single nucleotide polymorphisms (SNP), widely distributed over the genome, and with potentially known genomic locations and biological functions.

In addition, the assessment of genome-wide variation would provide the basis on which to identify loci with atypical patterns that would suggest the influence of locus-specific processes, such as selection. Furthermore, a sufficient number of genetic markers would enable better relatedness estimates and the reconstructions of family and multigenerational pedigrees in wild populations, a task for which a few markers, even if highly polymorphic, have proved insufficient in most natural settings.

Analysis of genetic variation

Secondly, and most importantly, a genomic approach would broaden the analysis of genetic variation beyond the purely neutral to include the variation potentially subjected to natural selection, be it either deleterious or beneficial. On the one hand, the possibility of assessing the adaptive component of genomic variation will facilitate the detection of local adaptations, the quantification of adaptive divergences between populations and the design of conservation and management strategies that preserve them.

In addition, genomic information would allow a better assessment of genetic risks in endangered populations, including the identification of genes responsible for diseases or congenital disorders, and the design of more effective, science-based management strategies.

 

A Koala, a species in the verge of the extinction.
A Koala, a species in the verge of the extinction.

 

Therefore, the leap from conservation genetics to conservation genomics has been identified as a priority task, which is becoming increasingly feasible and unavoidable after some recent technological and analytical developments have facilitated genome sequencing in non-model species at an affordable price. Recent studies validate some of the potential contributions that the availability of genome sequences can provide to endangered species conservation efforts.

Geomic approaches are greatly facilitated by the availability of a draft of the sequence of the whole genome of the targeted species or, at least, for a closely related species. Whole genome sequencing has remained out of the reach of most non-model organisms by their excessive cost. However, this enterprise is now becoming more tractable thanks to the advent of new genome sequencing technologies.

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