Forecasting changes in population genetic structure of alpine plants in response to global warming

Abstract

Species range shifts in response to climate and land use change are commonly forecasted with species distribution models based on species occurrence or abundance data. Although appealing, these models ignore the genetic structure of species, and the fact that different populations might respond in different ways because of adaptation to their environment. Here, we introduced ancestry distribution models, that is, statistical models of the spatial distribution of ancestry proportions, for forecasting intra-specific changes based on genetic admixture instead of species occurrence data. Using multi-locus genotypes and extensive geographic coverage of distribution data across the European Alps, we applied this approach to 20 alpine plant species considering a global increase in temperature from 0.25 to 4 °C. We forecasted the magnitudes of displacement of contact zones between plant populations potentially adapted to warmer environments and other populations. While a global trend of movement in a north-east direction was predicted, the magnitude of displacement was species-specific. For a temperature increase of 2 °C, contact zones were predicted to move by 92 km on average (minimum of 5 km, maximum of 212 km) and by 188 km for an increase of 4 °C (minimum of 11 km, maximum of 393 km). Intra-specific turnover-measuring the extent of change in global population genetic structure-was generally found to be moderate for 2 °C of temperature warming. For 4 °C of warming, however, the models indicated substantial intra-specific turnover for ten species. These results illustrate that, in spite of unavoidable simplifications, ancestry distribution models open new perspectives to forecast population genetic changes within species and complement more traditional distribution-based approaches.

From past to future: impact of climate change on range shifts and genetic diversity patterns of circumboreal plants

“…The changes in the genetic diversity patterns of these circumboreal plants depended on the type of molecular marker and patterns of genetic diversity distribution. This fact was also supported in a few other surveys, i.e., Collevatti et al (2011), Alsos et al (2012, Jay et al (2012), and Temunovic et al (2013). In the case of circumboreal plants, the expected future loss of geographic range was not necessary accompanied by a marked reduction of genetic diversity, but it has a strong effect on allelic richness, even if genetic diversity was quite uniformly distributed.…”

“…The homogeneity of the genetic background-the lack of admixture and the domination of one gene pool in most populations throughout the ranges of these two plants-becomes more pronounced in the future. In this case, the ancestry distribution model combined with geographic distribution of populations and environmental data (Jay et al 2012) assumes gene flow as the main component in the response of plant populations to environmental modifications and favors migration toward similar environments. Therefore, this model showed that resident genes can move to suitable places in a way that conserves the realized niche of a given genetic cluster.…”

“…This Bayesian algorithm incorporates genetic and geographic data and infers an admixture coefficient based on the correlation between environmental variables and individual ancestry (Jay 2011). POPS also provides a facility to estimate changes in population genetic structure under a scenario assuming future climate changes that can provide indirect estimates of future rates of gene migration (Jay et al 2012). …”

“…In recent years, climate has been more frequently considered as a factor shaping genetic resources within species, through species distribution shifts and increasing range fragmentation. Although surveys of genetic diversity under current climate conditions have a rich history in the literature, potential future impacts on the genetic diversity of species are rarely examined (Alsos et al 2009;Thomassen et al 2010;Beatty and Provan 2011;Collevatti et al 2011;Alsos et al 2012;Jay et al 2012;Eidesen et al 2013;Temunovic et al 2013;Steane et al 2014). Northern plant species could be more severely threatened than other species by recent and future climate change Parmesan 2006).…”

“…These models indicate potential rather than realized distributions, but the difference between recent and potential future distributions can be a source of valuable information on possible range shifts (Guisan and Thuiller 2005), the risk status of current ranges, and the dispersal rates required to reach suitable new habitats (Jump et al 2009). Based on ENM approaches, Jay et al (2012) implemented ancestry distribution models to forecast changes in intraspecific genetic diversity in response to climate change, using correlations between environmental variables and individual ancestry. Ancestry distribution models can help predict the future genetic resources of species, which is important for assessing their evolutionary potential and for management.…”