Search

By 2020, the genetic diversity of cultivated plants and farmed and domesticated animals and of wild relatives, including other socioeconomically as well as culturally valuable species, is maintained,and strategies have been developed and implemented for minimizing genetic erosion and safeguarding their genetic diversity. more...

Species diversification can increase resilience of British forests if diversifying species are adapted to site, genetically variable, and do not harm existing forests. Immediate increase in resilience is best achieved using native or well-established exotic species, rather than ‘alternative’ species. ‘Alternative’ species currently lack adequate information on site requirements and appropriate seed sources, and there has been little assessment of their potential for damaging existing forests through pest/pathogen transfer and invasive behaviour. Future use of ‘alternative’ species for diversification should be contingent on rigorous biological risk assessment, results from forestry scale trials, and the establishment of sustainable British seed sources. more...

The Arctic is undergoing dramatic environmental change with rapidly rising surface temperatures, accelerating sea ice decline and changing snow regimes, all of which influence tundra plant phenology. Despite these changes, no globally consistent direction of trends in spring phenology has been reported across the Arctic. While spring has advanced at some sites, spring has delayed or not changed at other sites, highlighting substantial unexplained variation. Here, we test the relative importance of local temperatures, local snow melt date and regional spring drop in sea ice extent as controls of variation in spring phenology across different sites and species. Trends in long‐term time series of spring leaf‐out and flowering (average span: 18 years) were highly variable for the 14 tundra species monitored at our four study sites on the Arctic coasts of Alaska, Canada and Greenland, ranging from advances of 10.06 days per decade to delays of 1.67 days per decade. Spring temperatures and the day of spring drop in sea ice extent advanced at all sites (average 1°C per decade and 21 days per decade, respectively), but only those sites with advances in snow melt (average 5 days advance per decade) also had advancing phenology. Variation in spring plant phenology was best explained by snow melt date (mean effect: 0.45 days advance in phenology per day advance snow melt) and, to a lesser extent, by mean spring temperature (mean effect: 2.39 days advance in phenology per °C). In contrast to previous studies examining sea ice and phenology at different spatial scales, regional spring drop in sea ice extent did not predict spring phenology for any species or site in our analysis. Our findings highlight that tundra vegetation responses to global change are more complex than a direct response to warming and emphasize the importance of snow melt as a local driver of tundra spring phenology. more...

To manage emerging forest diseases and prevent their occurrence in the future, it is essential to determine the origin(s) of the pathogens involved and identify the management practices that have ultimately caused disease problems. One such practice is the widespread planting of exotic tree species within the range of related native taxa. This can lead to emerging forest disease both by facilitating introduction of exotic pathogens and by providing susceptible hosts on which epidemics of native pathogens can develop. We used microsatellite markers to determine the origins of the pathogen Dothistroma septosporum responsible for the current outbreak of Dothistroma needle blight (DNB) on native Caledonian Scots pine (Pinus sylvestris) populations in Scotland and evaluated the role played by widespread planting of two exotic pine species in the development of the disease outbreak. We distinguished three races of D. septosporum in Scotland, one of low genetic diversity associated with introduced lodgepole pine (Pinus contorta), one of high diversity probably derived from the DNB epidemic on introduced Corsican pine (Pinus nigra subsp. laricio) in England and a third of intermediate diversity apparently endemic on Caledonian Scots pine. These races differed for both growth rate and exudate production in culture. Planting of exotic pine stands in the UK appears to have facilitated the introduction of two exotic races of D. septosporum into Scotland which now pose a threat to native Caledonian pines both directly and through potential hybridization and introgression with the endemic race. Our results indicate that both removal of exotic species from the vicinity of Caledonian pine populations and restriction of movement of planting material are required to minimize the impact of the current DNB outbreak. They also demonstrate that planting exotic species that are related to native species reduces rather than enhances the resilience of forests to pathogens. more...

Within the plant kingdom, many genera contain sister lineages with contrasting outcrossing and inbreeding mating systems that are known to hybridize. The evolutionary fate of these sister lineages is likely to be influenced by the extent to which they exchange genes. We measured gene flow between outcrossing Geum rivale and selfing Geum urbanum, sister species that hybridize in contemporary populations. We generated and used a draft genome of G. urbanum to develop dd‐RAD data scorable in both species. Coalescent analysis of RAD data from allopatric populations indicated that the species diverged 2–3 Mya, and that historical gene flow between them was extremely low (1 migrant every 25 generations). Comparison of genetic divergence between species in sympatry and allopatry, together with an analysis of allele frequencies in potential parental and hybrid populations, provided no evidence of contemporary introgression in sympatric populations. Cluster‐ and species‐specific marker analyses revealed that, apart from four early‐generation hybrids, individuals in sympatric populations fell into two genetically distinct groups that corresponded exactly to their morphological species classification with maximum individual admixture estimates of only 1–3%. However, we did observe joint segregation of four putatively introgressed SNPs across two scaffolds in the G. urbanum population that was associated with significant morphological variation, interpreted as tentative evidence for rare, recent interspecific gene flow. Overall, our results indicate that despite the presence of hybrids in contemporary populations, genetic exchange between G. rivale and G. urbanum has been extremely limited throughout their evolutionary history., https://doi.org/10.1111/mec.14444 more...

Landscape heterogeneity in floral communities has the potential to modify pollinator behaviour. Pollinator foraging varies with the diversity, abundance and spatial configuration of floral resources. However, the implications of this variation for pollen transfer and ultimately, the reproductive success of insect pollinated plants remains unclear, especially for species which are rare or isolated in the landscape. We used a landscape-scale experiment, coupled with microsatellite genotyping, to explore how the floral richness of habitats affected pollinator behaviour and pollination effectiveness. Small arrays of the partially self-compatible plant Californian poppy (Eschscholzia californica) were introduced across a landscape gradient to simulate rare, spatially-isolated populations. The effects on pollinator activity, outcrossing and plant reproduction were measured. In florally rich habitats, we found reduced pollen movement between plants, leading to fewer long-distance pollination events, lower plant outcrossing and a higher incidence of pollen limitation. This pattern indicates a potential reduction in per capita pollinator visitation, as suggested by the lower activity densities and richness of pollinators observed within florally rich habitats. In addition, seed production reduced by a factor of 1.8 in plants within florally rich habitats and progeny germination reduced by a factor of 1.2. We show this to be a consequence of self-fertilisation within the partially self-compatible plant, E.californica. These findings indicate that locally rare plants are at a competitive disadvantage within florally rich habitats because neighbouring plant species disrupt conspecific mating by co-opting pollinators. Ultimately, this Allee effect may play an important role in determining the long-term persistence of rarer plants in the landscape, both in terms of seed production and viability. Community context therefore requires consideration when designing and implementing conservation management for plants which are comparatively rare in the landscape. more...

BACKGROUND: Ramularia collo-cygni (Rcc) is responsible for Ramularia leaf spot (RLS), a foliar disease of barley contributing to serious economic losses. Protection against the disease has been almost exclusively based on fungicide applications, including Succinate Dehydrogenase Inhibitors (SDHIs). In 2015 the first field isolates of Rcc with reduced sensitivity to SDHIs were recorded in some European countries. In this study we established baseline sensitivity of Rcc to SDHIs in the UK and characterised mutations correlating with resistance to SDHIs in UV-generated mutants. RESULTS: Five SDHI resistant isolates were generated by UV mutagenesis. In four of these mutants a single amino acid change in a target succinate dehydrogenase (Sdh) protein was associated with decrease in sensitivity to SDHIs. Three of these mutations were stably inherited in the absence of SDHI fungicide and resistant isolates did not demonstrate a fitness penalty. There were no detectable declines in sensitivity in field populations in years 2010-2012 in the UK.CONCLUSIONS: SDHIs remain effective in controlling Rcc in the UK. However given that the first isolates of Rcc with reduced sensitivity appeared in other European countries in 2015, robust anti-resistance strategies need to be implemented to maintain effective disease control. more...

In recent years, British seed sourcing practice has tended to focus on the principle that “local-is-best” for native woodland creation. However, in the face of continuing and accelerating environmental change, the suitability of this approach has been called into question. In this article, we investigate the relevance and suitability of a series of seed sourcing strategies: maintaining the status quo by continuing to source local origin seed, sourcing seed from currently warmer locations, and the addition or replacement of species. Our main findings are that there are opportunities to increase the sophistication of existing guidance and that improvements would be timely. In any case, an important consideration is the capacity for newly established populations of trees to survive immediately and amidst increasingly variable environmental conditions. The current paucity of 2 knowledge of forest genetic resources in British populations of native tree species suggests that deviations from sourcing currently adapted planting stock are not uniformly applicable throughout the country and that any change to policy ought to be applied judiciously and only under a restricted set of circumstances. more...