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.

Local adaptation is a major driver of biological diversity, and related species may develop analogous (parallel evolution) or alternative (divergent evolution) solutions to similar ecological challenges. We expect these adaptive solutions between closely related organisms would culminate in both phenotypic and genotypic signals. In this study, we employ a reciprocal transplant, glasshouse experiment with two Eucalyptus species ( E. grandis and E. tereticornis) with large, overlapping distributions grown under contrasting ‘local’ temperature conditions (tropic and temperate) to investigate the independent contribution of adaptation, plasticity, and their interaction at molecular, physiological and morphological levels. We find key traits differ in their response. The link between gene expression and traits markedly differed between species. Divergent evolution was the dominant pattern driving adaptation as unique gene responses (91% of all significant genes) was the greatest factor driving differentiation; but overlapping gene (homologous) responses were dependent on the determining factor (plastic, adaptive, or genotype by environment interaction). 98% of the plastic homologs were similarly regulated, while 50% of the adaptive homologs and 100% of the interaction homologs were antagonistically regulated. Therefore, parallel evolution for the adaptive effect in homologous genes was greater than expected but not in favour of divergent evolution. Further, heat shock proteins for E. grandis were almost entirely driven by adaptive responses, while plasticity drove the response in E. tereticornis. These results suggest divergent molecular evolutionary solutions dominated the adaptive mechanisms among species, even in similar ecological circumstances. Thus, trees with overlapping distributions are unlikely to equally persist in the future, suggesting that management of future forests to changing temperature conditions must be species specific.