Wouter van der Bijl

@vdbijl.bsky.social

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Evolutionary biologist @ UBC.

Large-effect CNVs underlie sex-linked variation in colour pattern. a, GWAS peaks on autosomes with significant loci with sex-linked inheritance, near texim and in prex1. b, The relative coverage (1× = genome-wide sample average) across the region for 297 males (this study) and 3 females, calculated in moving windows of 1 kb, 100 bp apart. c, Phenotypic effects of the top variant (diamond in a) on ornaments O6 (orange pattern) and B5 and B7 (black pattern). The proportion of variation in the phenotype that is explained by the top SNP is displayed as Nagelkerke’s R2 from a logistic regression. d, Median estimated allele counts for the top SNP, based on read depth, for homozygous reference and heterozygous individuals. No heterozygous alternate individuals were found. e, PheWAS heat maps displaying z scores for the effect of the top variant on orange and black colour across the body, controlling for autosomal and sex-linked relatedness.
A Manhattan plot showing the association of genomic variants with ornament O2. Points represent genomic variants, with their genomic location on the x axis and the two-sided P value of the association on the y axis (from mixed effects GWAS). P values are displayed as uncorrected for multiple testing, with the dotted line denoting the 5% FDR level.
Orange ornaments are strongly heritable, and their incidence and size responded to selection. a, Pictograms of seven orange ornaments. b, Heritabilities of the incidence and size (when present) of each ornament. Dots and lines reflect point estimates and 95% credible intervals, and the gradient bars show the cumulative posterior density. c,d, The effect of selection on the incidence and size of orange ornaments. Bars and points represent means, with error bars showing 95% bootstrapped confidence intervals. x axes show consecutive generations. Sample size (number of fish); P generation: 300; downselected F 1, F2 and F3: 453, 570 and 441; upselected F 1, F2 and F3: 508, 513 and 444.
The localized heritability of colour is high, but the architecture is heterogeneous. a,b, The narrow-sense heritability of the presence of orange (a) and black (b) colour on the guppy body. For each heat map cell, a Bayesian animal model was used to estimate the contribution of additive genetic and environmental factors. Heritabilities are expressed as a proportion of the between-individual phenotypic variance. The autosomal, X-linked and Y-linked heritability add up to the total heritability. Body positions where the incidence of colour is less than 1% are coloured grey.
| Quantification of pattern variation. a, An overview of the phenotyping pipeline. From each photo, the fish is extracted, the body is aligned to a common reference shape using landmarks, and the position of orange and black colour is extracted.
More guppy males with unique patterns. Photos by Wouter van der Bijl & Jacelyn Shu.
Photo of guppy males from lab population, each showing a unique combination of black and orange ornaments. Photo by Wouter van der Bijl.
Me with a painting of Wallace