Fig. 2: Patterns of sexual dimorphism in dioicous brown algae.
a, Pie charts representing the fractions of sex-biased genes among expressed genes (FBGs in red and MBGs in blue) in the four dioicous species. The colour gradients represent the intensity of expression FC, from a 2FC difference to more than 15FC. The percentages are calculated on the basis of the total number of expressed genes averaged across sexes. F, female; M, male. b, Comparison of gene expression levels, in log2(TPM + 1), between males and females within dioicous species. The colour patterns follow the ones used in a, except the grey points, which represent unbiased genes that presented an FC > 2. c, Scatterplots of the lengths of cells of immature gametophytes of dioicous species. The means (solid points) and standard deviations (whiskers) are plotted per sex per species. The asterisks indicate significant differences between mean cell lengths, tested with two-sided t-tests. *0.01 < P < 0.05; ***P < 0.001. d, Representative micrographs of male and female immature gametophytes viewed under an inverted light microscope for each dioicous species investigated. The micrographs show individual algae, representative of 100–200 individuals grown in petri dishes. e, Linear regressions of the fraction of FBGs and MBGs (in red and blue, respectively) among the mean number of expressed genes across both sexes, against the mean difference in cell length recorded between the sexes (in µm), in the four dioicous species investigated. Linear regressions were fitted through the phylogenetic generalized least squares method, implemented in the R package nlme. We report values of adjusted r2 calculated with analysis of variance. NS, not significant.
