Geographical and environmental gradients shape phenotypic trait variation and genetic structure in Populus trichocarpa

Abstract

SummaryPopulus trichocarpa is widespread across western North America spanning extensive variation in photoperiod, growing season and climate. We investigated trait variation in P. trichocarpa using over 2000 trees from a common garden at Vancouver, Canada, representing replicate plantings of 461 genotypes originating from 136 provenance localities.We measured 40 traits encompassing phenological events, biomass accumulation, growth rates, and leaf, isotope and gas exchange-based ecophysiology traits. With replicated plantings and 29 354 single nucleotide polymorphisms (SNPs) from 3518 genes, we estimated both broad-sense trait heritability (H 2 ) and overall population genetic structure from principal component analysis.Populus trichocarpa had high phenotypic variation and moderate/high H 2 for many traits. values reflected trait correlation strength with geoclimate variables. The population genetic structure had one significant principal component (PC1) which correlated with daylength and showed enrichment for genes relating to circadian rhythm and photoperiod. Robust relationships between traits, population structure and geoclimate in P. trichocarpa reflect patterns which suggest that range-wide geographical and environment gradients have shaped its genotypic and phenotypic variability.

Adaptive genetic variation mediates bottom-up and top-down control in an aquatic ecosystem

“…This interaction demonstrates that population-level local adaptation in two species can impact ecosystem function in an intuitive way. The rapid rate at which evolution has occurred in these two species [28,32] suggests that these interactions could arise over relatively short, ecologically relevant timescales.…”

“…To manipulate intraspecific variation from the bottom-up, we selected five genotypes of black cottonwood (P. trichocarpa), a dominant riparian tree species native to western North America that exhibits local adaptation to site conditions in leaf chemistry, growing season and primary productivity [32,35,36]. These five genotypes originated from southern localities of British Columbia (BC), Canada, and were equally related [10].…”

“…Stickleback act as important predators in their natal lakes and in aquatic mesocosms [28,29], whereas seasonal pulses of leaf litter by terrestrial riparian plants can dictate trophic interactions and nutrient cycling as a cross ecosystem subsidy in a range of aquatic systems [30,31]. Genotypes of black cottonwood and ecotypes of stickleback both exhibit phenotypic variation from local adaptation to their natal environments [32,33]. To understand the importance of the direct and interactive effects of evolution, we ask two questions: (i) does intraspecific genetic variation in species at different trophic levels (i.e.…”

Population genomics of the eastern cottonwood (Populus deltoides)

“…Genetic structure is mainly driven by interspecific hybridization, isolation by distance, and natural selection (Evans et al., 2014; Geraldes et al., 2014; Slavov et al., 2012; Stölting et al., 2015; Wang et al., 2016b; Zhou et al., 2014). Adaptation has been shown to have a complex genetic architecture (Evans et al., 2014; Holliday et al., 2016; McKown, Guy, et al., 2014; McKown, Klápště, et al., 2014; Porth et al., 2015) and to be a driver of divergent evolution between species (Wang et al., 2016b). Contradictory estimates of LD decay have been reported for P. trichocarpa , with an early study on a reduced number of genes reporting fast LD decay below a threshold of 0.2 (200 bp, Wegrzyn et al., 2010).…”

Raznolikost i strukturiranost hrvatskih kontinentalnih i alpsko-dinarskih populacija bijele johe (Alnus incana /L./ Moench subsp. incana); geografska i okolišna izolacija kao uzrok fenotipske divergencije

“…In general, tree species have high levels of morphological variability (Poljak et al 2012;McKown et al 2014;Zebec et al 2015), and phenotypic differences among populations are often a result of the environmental distances between populations. Nevertheless, our results suggest that phenotypic divergence of the studied grey alder populations is the result of a significant level of isolation both by distance and by the environment.…”