Fig 1.
Batrachochytrium salamandrivorans zoospore attachment, zoospore production and zoosporangia maturation at 15°C.
A) Boxplot of the number of zoospores attaching within three hours after introduction of a solution of standardised zoospore concentration. B) Predicted time and size of maximum daily increase in zoospore concentration–indicating the predicted timing of sporulation for each isolate, thus providing an indication of generation time. Here the y axis represents the predicted daily increase in the zoospore count. We predict the timing of sporulation (timed from t0 of experiment) using simulated data from a generalise linear model with a negative binomial distribution and the formula zoospore count ~ isolate*day (R2 = 0.8), with day treated as a factor due to the observed non-linear relationship of zoospore count. The time period with the steepest daily increase in zoospore count was identified as the predicted period of sporulation. C) Sporangia count over time per isolate.
Fig 2.
Isolate growth at various temperature regimes.
Optimal polynomials fit to growth rates (r value (count.day-1), calculated by GrowthCurver considering total (spore + sporangia) counts) vs temperature data (line colour depicts isolate identity). (see Fig K in S1 Text for individual plots of growth curves against r values (count.day-1) and R2 values, and Fig L in S1 Text for other growth measures (generation time and carrying capacity) analysed for each isolate).
Fig 3.
Batrachochytrium salamandrivorans phenotypes: plasticity in zoospore motility.
A1) photographic representation, photographed at 20x magnification, scale bars represent 20μm. A2-A3) Scatterplots of standardized growth rates (r = black crosses, calculated from growth curves fit by GrowthCurver, standardized to bring onto a proportional scale as the proportion of immotile spores, by first calculating the average r value for each isolate at each temperature, identifying the maximum average r value for each isolate and dividing the extracted r values by this maximum average r value), with proportion of zoospores that are immotile, floating zoospores (coloured points- colour denotes incubation temperature). These plots are shown for all isolates in Fig R in S1 Text.
Fig 4.
Genomic variation within the European Batrachochytrium salamandrivorans epidemic.
A) RAxML inferred phylogeny of LD filtered SNPs of all isolates aligned to the BundBos2013 assembly (GCA_021556675.1), including BdJel423 reads as an outgroup, node values denote bootstrap support. B) GO Terms and descriptions enriched in the ortholog clusters within highest 10% of dn/ds values. BP = Biological Process, CC = Cellular component, MF = molecular function. C) Tajima’s D calculations of non-overlapping 10kb windows across BundBos2013 assembly (see Supplementary Methods for details).
Fig 5.
Correlation between genomic and phenotypic variation.
A) Principal component analyses (PCA), performed using prcomp() in R, with first four principle components (PCp) explaining 66.5% of variation of phenotypic data (spore counts, sporangia counts and mean sporangia size) across all temperatures and time points. Colour of isolate label and ellipses depict cluster identity according to K-mean clustering analysis. B) Estimates with 95% confidence intervals of coefficients from linear model (model structure PCp1*PCp2*PCp3* PCp4 ~ PCg1*PCg2*PCg3, R2 = 0.827) where PCg = genomic principle component and PCp = phenotypic principal component. C) Genomic PCA output. Pairwise scatterplots of first three principal components with isolates colour indicating isolate group as shown in legend positioned in D.
Fig 6.
Predicted timings of optimal growth of Bsal across fire salamander (Salamandra salamandra) distribution, coloured per meteorological season for overall interpretability.
A) Eifel2019, B) Luik2017, C) Rob2014 pixel colour depicts timing of peak Bsal growth where peak growth occurs in green = spring, yellow = summer, brown = autumn and blue = winter. Generated using shape file from https://www.geoboundaries.org/index.html#getdata.[60].