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Genetics, adaptive potential and fish conservation: Are we measuring the right thing?

Anthony S Moore and Anthony Moore

Southern Cross University, LISMORE, AUSTRALIA

THEME: ASFB

There is little doubt of the importance of genetic diversity and the adaptive potential it provides to respond to varying degrees of selection in changing environments. But are we measuring it correctly? Molecular markers have been embraced as the definitive tools to provide information on current and historical demographic processes, evolutionary distinctiveness, and population subdivision. In this role they are remain very powerfull tools. However, molecular markers are being used increasingly to estimate levels of adaptive potential within populations. The reasoning stems from the implicit assumption that molecular diversity reflects the overall functional genetic diversity and therefore the adaptive potential of a population. Two recent meta-analyses of large data sets have shown a very poor relationship between estimates of additive and neutral genetic variation. These empirical studies suggest either that the overall correlation between quantitative and molecular variation is weak or that the predominant methods we use to estimate this variation are inappropriate when assessing adaptive potential. We propose the use of quantitative genetic measures in conjunction with molecular techniques to better estimate the adaptive potential of populations. The adaptive potential of a population is envisaged here as a function of the additive genetic variation of multiple traits. For the purposes of conservation assessment the aim is to compare populations within a species. To do this an index of adaptive potential can be developed: A sample of traits is measured across all populations. Correlations between multiple traits are reduced by derivation of principle components. The additive variance for each component can then be assessed and coefficients of variation calculated. Maximum likelihood methods can be used to combine multiple 'independent' estimates into a consensus estimate of standardised additive variance across all components for each population. Until evidence accumulates to the contrary, it should not be assumed that measures of molecular diversity reflect the adaptive potential of a population.