Biology subjects

Carleial, R.

Publications and source records attributed to Carleial, R..

6 recordsLinked to original sources

bioRxiv2026

Genomic signals of local adaptation in UK black alder populations (Alnus glutinosa)

Black alder (Alnus glutinosa) is a native tree species in the British Isles, which it colonised after the last glaciation from continental refugia. It is now a widespread pioneer species, thriving on wetlands and riverbanks. We present whole genome sequence data for 324 alder seedlings grown from seed collected from 44 populations across the UK. Among these we found two triploids and one sample with trisomy at chromosome five. Removing these, we found little population genetic structure apart from diverging northern populations with lower diversity. Using Latent-Factor Mixed Models (LFMM) analyses we identified 1,364 loci whose allele frequencies were significantly associated with environmental variables. Of these loci, 93% were associated with the number of snow days. In contrast, the greatest total genomic signal (variance in SNP effect sizes of 7.38 million SNP loci) was observed for mean temperature of the wettest quarter and annual number of frost days. Estimates of maladaptation using 1.49 million SNPs, predicted that northern populations are worst adapted to present and future worst-case climates. Our results suggest that similarity of source-site temperature variables should be prioritised when choosing seed sources for new planting, and northern populations could benefit from assisted gene flow from the south.

plant biology↗

bioRxiv2026

Genetic mapping of Dutch elm disease resistance

Dutch elm disease (DED) has killed millions of field elms (Ulmus minor) in Britain and Europe since the 1970s, causing incalculable damage to landscapes and their associated biodiversity. While the species U. minor is highly susceptible to DED, some east Asian and Himalayan species of elm are resistant. These Asiatic species differ in their growth and form to U. minor and cannot fully substitute for it in the landscape. Several breeding programmes have attempted to generate trees that combine DED-resistance with the growth and form of U. minor via hybridisation and back-crossing. These have been partly successful, but further breeding is needed to fully realise these ambitions. Most recently in Britain, a complex resistant hybrid Wingham (FL493) was crossed with a surviving U. minor tree in Tonge Mill, Kent. Sixty progeny from this cross were tested for field resistance to DED and show segregation for this trait. Here, we analyse the genome of these progeny in order to: (1) construct a linkage map of the elm genome, and (2) identify regions of their genome derived from east Asian and Himalayan species that could be associated with DED-resistance. Such knowledge could accelerate future breeding programmes and enhance our understanding of the mechanistic basis of resistance.

genomics↗

bioRxiv2026

Genomic diversity of British native oaks: species differentiation, hybridisation and triploidy

The morphological continuum between Britains two native oak species helped Darwin formulate his "one long argument" in The Origin of Species. Here we comprehensively analyse the genome-wide differentiation of 418 individuals from 60 British oak populations. Using 7 million biallelic SNPs, we find evidence for two species with islands of variation containing 8,230 SNPs of which 2,005 are within gene annotations. We find extensive hybridisation and back-crossing between the species, and this is biased in favour of introgression from Quercus robur into Q. petraea. Chloroplasts are shared between the species, mainly of haplotypes derived from Iberian glacial refugia. Genomic allocation of species and hybrids allows analysis of niche differentiation, showing that a larger Q. robur component is disproportionately found in warmer and more thermally variable environments with alkaline soils, while a larger Q. petraea component is found in more topographically complex terrain with high rainfall. This leads us to emphasise the balance between the opposing forces of hybridisation and niche differentiation in explaining the continuum between the two species. Using long-term field data, we show that stem growth over three decades was higher in Q. robur than in Q. petraea or hybrids, but this difference could be explained by environmental factors. In contrast, the five triploid trees in our sample grew significantly faster than diploids even after accounting for environmental effects, suggesting that triploids could be a valuable economic resource.

evolutionary biology↗

bioRxiv2026

Genomic basis for resistance to acute oak decline and mildew infection in English oak

English oak (Q. robur) in Britain is at risk from a young age due to powdery mildew and at maturity due to acute oak decline (AOD). The contribution of oak genetic diversity to these conditions is a critical question that until recently would have required extensive clonal or family trials of juvenile and mature oak trees. Here we overcome this practical burden with genomic approaches inspired by medicine. We sequence 1868 oak trees from 78 sites and identify 1491 trees exclusively of the species Q. robur, which we analyse. Using single nucleotide polymorphism (SNP) based estimates of heritability ([Formula]), we estimate 20.9% of variation in AOD presence is genetically determined. For mildew symptoms, [Formula] is 27.8%. Using genome-wide association studies, no SNP markers show a significant association with AOD, but 183 are significantly associated with mildew. Genomic prediction models for AOD and its symptoms, using thousands of loci, give low to moderate accuracies, ranging from 0.187 to 0.617. These results suggest a highly polygenic heritable component of susceptibility to AOD, which perhaps reflects the number of biotic and abiotic factors known to contribute to it. In contrast, powdery mildew, caused by a single fungus, has an oligogenic heritable component controlled by fewer loci of large effect. These results could be used to inform breeding programs to develop trees more resistant to AOD and mildew.

evolutionary biology↗

bioRxiv2025

Genetic basis of traits and local adaptation in UK silver birch

Knowledge of the genomic basis of phenotypes in forest trees lags that of other economically important organisms. We sequenced the genomes of 2054 silver birch trees from 20-year-old field trials at three locations in Britain. Each trial site contains trees from the same 29 source populations, and one trial site (Drummond) is outside the climate envelope of the source sites. We discovered many single nucleotide polymorphisms (SNP), and a structural polymorphism, associated with several growth traits. Using models trained with genome-wide SNPs we estimate the genomic breeding values of 148 plus trees. We discover 117 SNPs significantly associated with source-site environmental variables, but genetic offset estimates using these SNPs provide poor predictions of tree growth rates (Drummond excluded). They are outperformed in this task by offset estimates using thousands of non-significant SNPs. Such estimates for Drummond in current climates are higher than for source sites under a future worst case climate scenario.

genomics↗

bioRxiv2022

A first draft genome of Holm oak (Quercus ilex L.), the most representative species of the Mediterranean forest and the Spanish agrosilvopastoral ecosystem dehesa

The holm oak (Quercus ilex L.) is the most representative species of the Mediterranean Basin and the agrosilvopastoral Spanish "dehesa" ecosystem. Being part of our life, culture, and subsistence since ancient times, it has great environmental and economic importance. More recently, there has been a renewed interest in using the Q. ilex acorn as a functional food due to its nutritional and nutraceutical properties. However, the holm oak and its related ecosystems are threatened by different factors, with oak decline syndrome and climate change being the most worrying on the short and medium term. Breeding programs informed by selection of elite genotypes seems to be the only plausible biotechnological solution to rescue populations under threat. To achieve this and other downstream analyses, we need a high-quality Q. ilex reference genome. Here, we introduce the first draft genome assembly of Q. ilex using long-read sequencing (PacBio). The assembled nuclear haploid genome has 530 contigs totaling 842.2 Mbp (N50 = 3.3 Mbp), of which 448.7 Mb (53%) are repetitive sequences. We annotated 39,443 protein-coding genes and Benchmarking Universal Single-Copy Orthologs analysis detected 412 out of 425 expected complete and single-copy genes (94.80%) within the Q. ilex genome. The chloroplast genome size was 142.3 Kbp with 149 protein-coding genes successfully annotated. This first draft should allow for the validation of - omics data as well as the identification and functional annotation of genes related to phenotypes of interest such as those associated to resilience against oak decline syndrome and climate change, higher acorn productivity and nutraceutical value.

genomics↗