Prospects and limitations of genomic offset in conservation management

Abstract

In nature conservation, there is keen interest in predicting how populations will respond to environmental changes such as climate change. These predictions can help determine whether a population can be self‐sustaining under future alterations of its habitat or whether it may require human intervention such as protection, restoration, or assisted migration. An increasingly popular approach in this respect is the concept of genomic offset, which combines genomic and environmental data from different time points and/or locations to assess the degree of possible maladaptation to new environmental conditions. Here, we argue that the concept of genomic offset holds great potential, but an exploration of its risks and limitations is needed to use it for recommendations in conservation or assisted migration. After briefly describing the concept, we list important issues to consider (e.g., statistical frameworks, population genetic structure, migration, independent evidence) when using genomic offset or developing these methods further. We conclude that genomic offset is an area of development that still lacks some important features and should be used in combination with other approaches to inform conservation measures.

Climate adaptation and vulnerability of foundation species in a global change hotspot

“…Despite their promise for inferring climate adaptation (and its predicted loss) in non-model organisms with limited tractability to experimentation (Fitzpatrick et al, 2021), the genomic tools used here have limitations that should be acknowledged (reviewed in Capblancq et al, 2020; Hoffmann et al, 2021; Rellstab et al, 2021). For instance, predictions of genomic vulnerability do not account for the ability of populations to adapt to climate change using standing genetic variation, or gene flow from other, well-adapted populations across a species’ range (which, as noted, could especially benefit G. gemineoa ).…”

Adaptive potential of Coffea canephora from Uganda in response to climate change

“…In line with the risk of nonadaptedness (RONA, Rellstab et al, 2016), we proposed a new measure of genetic offset defined as a “genetically weighted environmental distance”, in which weights correspond to the effect of the environment on adaptive loci. The measure improved RONA by including weights that are adjusted for the confounding effect of population structure (Rellstab et al, 2021). For C. canephora , the estimated genetic offsets allowed us to compare the level of genetic changes required between the different populations for them to maintain their genotype‐environment association.…”

Shallow environmental gradients can cause range margins to form

“…For example, “assisted migration” can be implemented to achieve an estimated “trait shift” needed to avoid severe maladaptation (and hence extinction) under future environmental conditions, or to simply assist the movement of a population towards new areas where the population would suffer from a smaller (estimated) risk of maladaptation (see e.g. Rellstab et al [2021]). Notably, our results show that situations exist such that a steepening gradient in the optimum of an adaptive trait can be very shallow (almost flat) throughout the entire contemporary range (but not necessarily outside of the realised range), and yet it can have a fundamental role in the establishment of range margins.…”