Evidence of divergent selection for drought and cold tolerance at landscape and local scales in Abies alba Mill. in the French Mediterranean Alps

Abstract

Understanding local adaptation in forest trees is currently a key research and societal priority. Geographically and ecologically marginal populations provide ideal case studies, because environmental stress along with reduced gene flow can facilitate the establishment of locally adapted populations. We sampled European silver fir (Abies alba Mill.) trees in the French Mediterranean Alps, along the margin of its distribution range, from pairs of high- and low-elevation plots on four different mountains situated along a 170-km east-west transect. The analysis of 267 SNP loci from 175 candidate genes suggested a neutral pattern of east-west isolation by distance among mountain sites. F(ST) outlier tests revealed 16 SNPs that showed patterns of divergent selection. Plot climate was characterized using both in situ measurements and gridded data that revealed marked differences between and within mountains with different trends depending on the season. Association between allelic frequencies and bioclimatic variables revealed eight genes that contained candidate SNPs, of which two were also detected using F(ST) outlier methods. All SNPs were associated with winter drought, and one of them showed strong evidence of selection with respect to elevation. Q(ST)-F(ST) tests for fitness-related traits measured in a common garden suggested adaptive divergence for the date of bud flush and for growth rate. Overall, our results suggest a complex adaptive picture for A. alba in the southern French Alps where, during the east-to-west Holocene recolonization, locally advantageous genetic variants established at both the landscape and local scales.

Water availability drives signatures of local adaptation in whitebark pine (Pinus albicaulis Engelm.) across fine spatial scales of the Lake Tahoe Basin, USA

“…; Roschanksi et al . ) providing further support that fine spatial scales are relevant to adaptation (Richardson et al . ).…”

“…; Roschanksi et al . ). Thus, studies which investigate adaptation at scales amenable to management may be of relatively greater importance (especially for endangered and threatened species) to reforestation applications such as those carried out through seed sourcing ( sensu McLane & Aitken ) and replanting efforts.…”

Landscape Population Genomics of Forsythia (Forsythia suspensa) Reveal That Ecological Habitats Determine the Adaptive Evolution of Species

“…For A. bidentata , the highest number of EAL is associated with its ecological habitats of “cold intolerance” and “avoiding waterlogging.” For C. coggygria , the highest number of EAL is associated with its ecological habitat of “avoiding waterlogging.” To further confirm the universality of our hypothesis, we reviewed the recent landscape population genomics studies in other regions. For example, the high number of EAL in Picea mariana is related to its ecological habitat of “cold resistance” (Prunier et al, 2011); additionally, EAL is related to “drought resistance” in Alnus glutinosa (De Kort et al, 2014), to “temperature and precipitation sensitivity” in Cephalotaxus oliveri (Wang et al, 2016), and to “drought and cold tolerance” in Abies alba (Roschanski et al, 2016). Based on the above-mentioned evidence, the hypothesis that the ecological habitats determine adaptive evolution of species possibly demonstrate a certain degree of universality.…”

Population genetics analysis in a relic population of silver fir (Abies alba Mill.) in southern Italy: A comparison with microsatellites and reference data

“…Seeds from southern Italy (Calabria) showed pronounced variability and higher vitality and vigour than the ones from central and north-eastern Europe (Larsen 1981, 1986a, 1986bin Bergmann et al 1990. A recent study in marginal populations of A. alba from French Mediterranean Alps showed the occurrence of several locally advantageous genetic variants involved in drought and cold tolerance (Roschanski et al 2016), highlighting how reduced gene flow due to isolation can facilitate the establishment of local adaptation. Similarly, significant differences in growth trends and climate responses in silver firs across the Carpathian Arc were found to coincide with the different postglacial history of north-south populations (Bosela et al 2016).…”