Genetic offset and vulnerability modelling under climate change scenarios: common misinterpretations and violations of evolutionary principles.

Abstract

Genetic offset models have become a popular component of the landscape genetics toolbox, with over 600 peer-reviewed publications applying these models. Genetic offset models are most frequently performed following the identification of putatively adaptive alleles from genotype-environment association analyses in natural populations of non-model organisms. These models allow the researcher to make predictions about the vulnerability of species populations to climate change, by estimating the extent of genetic change needed (i.e., genetic offset) to maintain 'optimal' allele frequencies and population fitness under future climate change scenarios. However, several review articles have recently drawn attention to fundamental limitations of genetic offset models that compromise their reliability for interpretation. In this commentary, we consolidate and build on previews reviews by describing several key assumptions and violations of basic evolutionary principles that are often overlooked when undertaking these analyses. We use a combination of evolutionary theory and conceptual descriptions to show that current applications fail to account for critical evolutionary processes that shape the selection-fitness landscape and risk producing misleading estimates of population vulnerability. While genetic offset models could have a place in the future, our current interpretations and applications remain problematic and are likely to lead to poor conservation outcomes.