Genetic offset and vulnerability modelling: misinterpretations of results and violations of evolutionary principles

Abstract

Genetic offset models have become a popular component of the landscape genetics toolbox, with over 150 peer-reviewed publications applying these models to plant and animal systems. 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 likely 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, a number of critical assumptions and knowledge gaps are often overlooked when undertaking these analyses, undermining their reliability and usefulness for making genetically informed management decisions. In this commentary, we describe seven assumptions in detail and discuss a range of common violations that can lead to misleading outcomes. While genetic offset models may have a place for predicting the vulnerability of natural populations of non-model organisms in the future, we argue that current applications are likely to be problematic and risk both wasting resources and misleading conservation management.