bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.03.18.585477

Low effective population size but high heterozygosity revealed by SNP analyses in adult and juvenile Thuja plicata in UK Woodlands

Guillardin, L.·MacKay, J.·Kerr, G.·Glover, E.
View original source ↗Export metadata ↓

Abstract

Thuja plicata is a conifer tree that is appreciated for its cultural, ecological and wood quality features in its natural range in western North America. It is also used in Europe and the UK for timber production. Some T. Plicata plantations in the UK are converted to Continuous Cover Forestry (CCF) management which uses natural regeneration and concerns have been raised about the genetic diversity in both the adult trees and the offspring. We studied species diversity, stand structure, and genetic diversity in four UK woodlands planted with T. plicata which contained both adults and naturally regenerated individuals. We discovered 61,104 Single Nucleotide Polymorphisms (SNPs) using Genotyping-by-Sequencing (GBS) and retained 504 SNPs for analysis. We selected 67 SNPs for PCR-based genotyping of 163 adults and 176 juveniles. We found a large number of monomorphic sites (40.3%) most of which were restricted to adults in a single woodland, indicative of a high genetic differentiation among woodlands. The effective population size (Ne) was very low across all sites (Ne < 100), varied between adults and juveniles, and was lowest in the most diverse woodland in terms of species and structure. In contrast, heterozygosity was high overall (Ho = 0.38), except in the divergent woodland (Ho = 0.26), and did not vary between adults and juveniles. Our findings and genotyping methods provide insights into the ability of CCF-managed woodlands, including instances of low genetic diversity in T. plicata, to face environmental shifts and disease threats.

Explore related subjects

genomicsPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Guillardin, L., MacKay, J., Kerr, G., Glover, E.. 2024-03-19. Low effective population size but high heterozygosity revealed by SNP analyses in adult and juvenile Thuja plicata in UK Woodlands. https://doi.org/10.1101/2024.03.18.585477

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Genomic correlates of metastatic competence and progression in human melanoma

Genomic events and their timing that grant a primary tumour the competence to disseminate remain poorly defined. We performed sequencing of 247 stage I/II primary cutaneous melanomas (CMs) and 60 matched metastases without intervening therapy from a prospectively followed registry cohort with a median followup of 92 months, integrating copy-number, mutational, protein and spatial-transcriptomic analyses. Relapse was not distinguished by oncogenic point mutations, which were largely shared between primaries and metastases, but by somatic copy-number alterations (SCNAs) and global chromosomal instability. We defined OncoCycle, a six-gene copy-number signature (amplification of CDK4, MCL1 and CD276; biallelic loss of CDKN2A, CDKN2B and TP53BP1) that predicted relapse independently of established clinicopathological features in melanoma, and a pan-cancer analysis. In matched pairs, metastatic progression was driven by continued copy-number evolution and reduction in intra-tumoural heterogeneity, rather than by acquired point mutations, and OncoCycle alterations from primary tumours were preserved in metastasis seeding clones. Clonal reconstruction revealed both monoclonal and polyclonal metastasis seeding, and spatial transcriptomics resolved copy-number-defined metastatic subclones occupying and programming distinct immune and stromal niches. Thus, metastatic competence was primed early by focal SCNAs on a background of chromosomal instability, elaborated by continued copy-number evolution during dissemination and spatio-temporal interactions with the tumour-microenvironment.

genomics↗
bioRxiv2026

PfPHAST: Plasmodium falciparum Public Health Amplicon Sequencing Tool, a Streamlined Panel for Malaria Genomic Surveillance

Genomic tools can support malaria control policy through surveillance of Plasmodium falciparum populations, tracking antimalarial drug resistance, pfhrp2/3 deletions that compromise rapid diagnostic tests, and selection at the circumsporozoite protein (PfCSP) vaccine target, as well as through molecular correction of therapeutic efficacy studies (TES). Multiplex Amplicons for Drug, Diagnostic, Diversity, and Differentiation Haplotypes using Targeted Resequencing (MAD4HatTeR), a comprehensive amplicon sequencing panel covering up to 276 targets, supports these applications but is tailored to research rather than routine programmatic use. We developed P. falciparum Public Health Amplicon Sequencing Tool (PfPHAST), a 56-target derivative of MAD4HatTeR spanning drug resistance loci, pfhrp2/3 deletion, PfCSP genotyping, non-falciparum species identification, and 20 high-heterozygosity microhaplotype loci for TES classification. We compared PfPHAST and MAD4HatTeR using laboratory strain controls, including two-strain dilution series and a five-strain mixture, across parasite densities of 100 to 10,000 parasites/L. At matched per-target depth, PfPHAST achieved a higher quality-control pass rate than MAD4HatTeR (94.4% versus 90.0%) and distributed reads more evenly across targets. The panels showed comparable recall and precision for drug resistance codons and microhaplotypes, reaching near-complete recall above 40% within-sample allele frequency (WSAF) at all densities, with reduced sensitivity for minor alleles below 10% WSAF at low parasite density in both panels. Observed and expected WSAF correlated strongly for both panels, and both resolved a five-strain polyclonal mixture, including a 5% minor strain. By concentrating sequencing capacity on targets of greatest programmatic relevance, PfPHAST offers a scalable, lower-cost alternative to comprehensive research panels without sacrificing performance on shared targets, complementing MAD4HatTeR for routine molecular malaria surveillance.

genomics↗
bioRxiv2026

Structural variation in repeat elements is widespread in normal human tissues and in tumorigenesis

Somatic mosaicism contributes to genomic variation, yet postzygotic structural variants remain under-characterized. We performed long- and short-read WGS from multiple individuals (n=47 normal tissues; n=168 samples) and identified mosaic structural variants in all individuals and germ layers, impacting a median 285.2 kb/genome. Nearly half of breakpoints were independently validated, with tissue distributions reflecting both early and late developmental origins. Most mosaic variants were repeat-mediated and 8.3% overlapped functional elements, an enrichment compared to germline variants. To extend these analyses in samples where long-read sequencing is infeasible, we measured repeat alterations from short-read sequencing, recapitulating mosaic tissue-specific differences. We characterized tumor- and tissue- specific variation in repeats across 15 cancer types and found tumor-related repeat variation to be similar in scale to that of normal mosaic variation. Tracking repeat changes in cell-free DNA provided a noninvasive approach for tumor monitoring. Our analyses revealed widespread repeat-driven structural variation in health and disease.

genomics↗