Genetic differentiation in Scottish populations of the pine beauty moth Panolis flammea (Lepidoptera: Noctuidae)

Pine beauty moth, Panolis flammea (Denis & Schiffermüller), is a recent but persistent pest of lodgepole pine plantations in Scotland, but exists naturally at low levels within remnants and plantations of Scots pine. To test whether separate host races occur in lodgepole and Scots pine stands and to examine colonization dynamics, allozyme, randomly amplified polymorphic DNA (RAPD) and mitochondrial variation were screened within a range of Scottish samples. RAPD analysis indicated limited long distance dispersal (FST = 0.099), and significant isolation by distance (P < 0.05); but that colonization between more proximate populations was often variable, from extensive to limited exchange. When compared with material from Germany, Scottish samples were found to be more diverse and significantly differentiated for all markers. For mtDNA, two highly divergent groups of haplotypes were evident, one group contained both German and Scottish samples and the other was predominantly Scottish. No genetic differentiation was evident between P. flammea populations sampled from different hosts, and no diversity bottleneck was observed in the lodgepole group. Indeed, lodgepole stands appear to have been colonized on multiple occasions from Scots pine sources and neighbouring populations on different hosts are close to panmixia.A.J. Lowe, B.J. Hicks, K. Worley, R.A. Ennos, J.D. Morman, G. Stone and A.D. Wat

Neighbouring Scots pine populations from contrasting climatic regions show substantial variability but consistent response to warming

Natural tree populations consist of individuals that exhibit intraspecific adaptive variation at a range of geographic scales, as a result of the balance between gene flow and selection. The spatial distribution and magnitude of such variation will influence the capacity of populations to adapt to forthcoming changing environmental conditions. The native Scots pine populations in Scotland represent what remains of the iconic Caledonian forest. Despite being distributed within a relatively narrow geographic area these populations occur across a steep East-West environmental gradient of increasing rainfall and temperature. We hypothesised that western populations compared to those from the east may be better adapted to warmer conditions and as a consequence, may respond differently to the increased temperature predicted during climate change. We conducted an experiment lasting 22 weeks in controlled environment chambers using a nested hierarchical design based on material from different regions (west or east), populations and families (half sibs). We examined the effects of two temperature scenarios, current temperature and warmer predicted temperature on percentage germination as well as growth and morphology of above and below-ground traits. Most of the variation occurred at the family level. Nevertheless, significant regional and population differences were detected, where eastern populations invested more in roots, exhibited fewer stomatal rows per needle and produced thinner roots. In addition, warmer temperatures had strong effects on early growth that were consistent in material from both regions and resulted in earlier germination, greater growth and biomass, but these effects were not accompanied by shifts in biomass partitioning. Although the strong effect of warming suggested temperature limitation for early growth in the study areas under current conditions our results did not support the idea that low seedling recruitment resulting from poor emergence and early growth would lead to a decline in Scottish populations of Scots pine under a warmer climate. Our results are informative regarding the adaptive potential in the populations and will contribute to the development of appropriate forest conservation strategies

Environmental factors and host genetic variation shape the fungal endophyte communities within needles of Scots pine (Pinus sylvestris)

To determine the role of environmental and host genetic factors in shaping fungal endophyte communities we used culturing and metabarcoding techniques to quantify fungal taxa within healthy Scots pine (Pinus sylvestris) needles in a 7-y old provenance-progeny trial replicated at three sites. Both methods revealed a community of ascomycete and basidiomycete taxa dominated by the needle pathogen Lophodermium seditiosum. Differences in fungal endophyte taxon composition and diversity indices were highly significant among trial sites. Within two sites, fungal endophyte communities varied significantly among provenances. Furthermore, the communities differed significantly among maternal families within provenances in 11/15 and 7/15 comparisons involving culture and metabarcoding data respectively. We conclude that both environmental and host genetic variation shape the fungal endophyte community of P. sylvestris needles

Allozyme variation and genetic structure of calluna vulgaris (heather) populations in scotland: the effect of postglacial recolonization

Recent fragmentation of populations as well as historical postglacial recolonization may have significantly affected the population genetic diversity of temperate plant species. Regional allozymic variability was measured at seven loci within and among 12 populations of Calluna vulgaris in the previously glaciated region of Scotland. These results were compared with existing data on south-western continental populations. Low genetic differentiation (FST = 0.024) and lack of consistent geographical pattern were found at the regional level among Scottish populations, implying a high rate of gene flow (Nm = 10.2), probably favoured by the nearly continuous range of C. vulgaris across Scotland and characteristics of the Scottish environment. Scottish populations possessed lower mean allozymic diversity (PLP = 40.48, A = 1.95, He = 0.133) than populations from all the continental regions investigated previously. Belgian populations were genetically more closely related to Scottish than to other continental populations. These last two findings are interpreted with regard to the evolutionary history of the species revealed by palynological data

Clinal genetic variation and phenotypic plasticity in leaf phenology, growth and stem form in common ash (Fraxinus excelsior L.)

Genetic variation and phenotypic plasticity play a role in determining the performance of a tree provenance at a planting site. This paper explores their relative importance in determining growth, phenology and tree form in a broad geographic sample of 42 British provenances of common ash (Fraxinus excelsior L.) grown at two contrasting trial sites. We found significant genetic differences for tree height, timing of leaf flushing and leaf senescence, and stem forking among the provenances. These followed a clear latitudinal and climatic cline, where the northern provenances were shorter, their leaves flushed later and senesced earlier than the southern provenances. Provenance explained a much larger proportion of the variance for spring phenology (63 per cent) than for autumn phenology (15 per cent). The effect of the planting site was contrasting between spring and autumn: spring phenology showed very little plasticity, while autumn phenology presented higher levels of phenotypic plasticity. This could indicate that for ash spring phenology is under stronger selective pressure. We found a correlation between tree height, leaf phenology and forking, with early flushing provenances tending to be taller and more forked, which could reflect repeated frost damage. The findings underline the complexity of predicting performance in novel environments and demonstrate that small gains in tree growth may be counteracted by detrimental effects on stem form, a key contributor to timber value, due to susceptibility to the contemporary environment