Comparison of range-wide chloroplast microsatellite and needle trait variation patterns in Pinus mugo Turra (dwarf mountain pine)

Abstract

In this study, range-wide genetic variation was analysed in 553 Pinus mugo Turra (dwarf mountain pine) individuals from 21 locations using 11 chloroplast microsatellites. Our main goal was to assess the spatial distribution of neutral genetic variation. We also used data from a previous study on the morphological variation of needles from 18 stands of P. mugo. In total, 22 needle characteristics were reanalysed and compared to microsatellite data to describe the distribution of morphological variation in the context of neutral genetic variation. We hypothesised that the chloroplast microsatellite and needle trait variation patterns would not entirely overlap. The results indicate the recent divergence of P. mugo populations derived from a formerly larger distribution. We identified 4 genetic and 3 morphological clusters whose spatial distribution overlapped only to some extent. The distribution of genetic variation showed a south-north pattern with signs of admixture in the Alps and Carpathians. Two south-westernmost stands from Italy were evidently isolated from the others. In contrast, morphological variation tended to display a west-east pattern. A separate group based on needle traits was formed mostly by eastern stands and was not observed by microsatellite analysis. In addition, a few needle characteristics significantly correlated with longitude and climate variables. These findings suggest that eastern populations of P. mugo may be of different origin and/or that some needle characteristics may be adaptively important in these locations. The potential roles of past demographic events, phenotypic plasticity and local adaptation in shaping the patterns of genetic and morphological variation in P. mugo are discussed.

Molecular and paleo‐climatic data uncover the impact of an ancient bottleneck on the demographic history and contemporary genetic structure of endangered Pinus uliginosa

“…Our mean F ST values were 2–3 times larger for both types of markers in P. uliginosa , even excluding the highly differentiated population from Ukraine. Similarly, a high level of differentiation was found in P. mugo among populations inhabiting different mountain ranges, including the Sudetes, Alps, and Carpathians (Heuertz et al, 2010; Dzialuk et al, 2017; Żukowska et al, 2017), which can reflect the past fragmentation and long reproductive isolation between the stands (Dzialuk et al, 2017).…”

“…Specifically, we used nSSR loci: psyl2, psyl25, psyl36, psyl42, psyl44, psyl57 (Sebastiani et al, 2012), ptTX3025, ptTX4001 , and ptTX4011 (Zhou et al, 2002); and cpSSR loci: PCP1289, PCP26106, PCP30277, PCP36567, PCP41131, PCP45071, PCP87314, PCP102652 (Provan et al, 1998), Pt15169, Pt26081, Pt30204 , and Pt71936 (Vendramin et al, 1996). Genotyping methodology and raw nSSR and cpSSR data of P. mugo and P. sylvestris were derived from earlier studies (Wójkiewicz et al, 2016; Wójkiewicz & Wachowiak, 2016; Żukowska et al, 2017; Żukowska & Wachowiak, 2017). To avoid bias in assessing the population structure due to the presence of false homozygotes (Chapuis & Estoup, 2007), the frequency of null alleles in the dataset was assessed using Micro‐Checker v. 2.2.3 (Van Oosterhout et al, 2004).…”

Candidate Genes for the High-Altitude Adaptations of Two Mountain Pine Taxa

“…Only the Abruzzian site M16 emerged as an individual cluster in Bayesian clustering under K = 7. Earlier studies showed that trees from that population exhibit many phenotypic [ 18 , 21 ] and genetic [ 43 , 44 ] characteristics of Pyrenean pines. The present investigation on nuclear markers, however, cannot conclusively confirm the introgression hypothesis, as the population as a whole did not differ from others of its species, neither being more distant nor showing exceptional pairwise Fst estimates.…”