Monitoring adaptive genetic responses to environmental change

Abstract

Widespread environmental changes including climate change, selective harvesting and landscape alterations now greatly affect selection regimes for most organisms. How animals and plants can adapt to these altered environments via contemporary evolution is thus of strong interest. We discuss how to use genetic monitoring to study adaptive responses via repeated analysis of the same populations over time, distinguishing between phenotypic and molecular genetics approaches. After describing monitoring designs, we develop explicit criteria for demonstrating adaptive responses, which include testing for selection and establishing clear links between genetic and environmental change. We then review a few exemplary studies that explore adaptive responses to climate change in Drosophila, selective responses to hunting and fishing, and contemporary evolution in Daphnia using resurrected resting eggs. We further review a broader set of 44 studies to assess how well they meet the proposed criteria, and conclude that only 23% fulfill all criteria. Approximately half (43%) of these studies failed to rule out the alternative hypothesis of replacement by a different, better-adapted population. Likewise, 34% of the studies based on phenotypic variation did not test for selection as opposed to drift. These shortcomings can be addressed via improved experimental designs and statistical testing. We foresee monitoring of adaptive responses as a future valuable tool in conservation biology, for identifying populations unable to evolve at sufficiently high rates and for identifying possible donor populations for genetic rescue. Technological advances will further augment the realization of this potential, especially next-generation sequencing technologies that allow for monitoring at the level of whole genomes.

Understanding and monitoring the consequences of human impacts on intraspecific variation

“…The answer here will be species‐specific, taking into account information on life histories and generation times, and also environment‐specific, taking into account information on the timescale and “color” (autocorrelation) of environmental variation (e.g., de Barba et al., 2010; Dowling et al., 2014; Gotanda & Hendry, 2014; Hansen et al., 2012; Schwartz et al., 2007). At the very least, a few generations are necessary to reliably infer trends; however, many studies have found that considerably longer time frames are needed for reliable inference.…”

Population Genomics of Marine Fishes: Next-Generation Prospects and Challenges

“…However, despite large quantities of phenotypic data, unequivocal evidence for recent genetic changes as a response to fishing pressure or temperature changes is still largely missing (Kuparinen and Merilä, 2007;Merilä and Hendry, 2014). Here, genomic data would greatly improve our ability to detect genetic change associated with specific environmental drivers and thereby to exclude alternative explanations, such as phenotypic plasticity and population replacement (Gienapp et al, 2008;Hansen et al, 2012;Therkildsen et al, 2013a; also see following section on spatio-temporal population genomics).…”

Evolutionary rescue in vertebrates: evidence, applications and uncertainty

“…For instance, the animal model [80] is now commonly used in the wild to estimate additive genetic variation, a critical component of the evolutionary potential of a trait. To our knowledge, no examples of the application of the animal model to ER yet exist; however, several authors have highlighted its potential [81][82][83]. High throughput genomic techniques with large sets of microsatellites loci and/or high-density SNP data provide helpful tools to achieve this objective [80].…”