Fig. 5: Tests of two evolutionary hypotheses for evolutionary dynamics of fetal–maternal communication, disambiguation9 and escalation10.
From: Cell type and cell signalling innovations underlying mammalian pregnancy
a, Design for disambiguation test. F, fetal; M, maternal. b, Observed versus expected numbers of co-expressed, fetal-only and maternal-only ligands, by ligand family. Points with solid colour have both P < 0.05 and Benjamini–Hochberg false discovery rate q < 0.05. c, Disambiguation status of select ligands. Blue, maternal-only; red, fetal-only; faint, co-expressed. d, Transition matrix of expression of secreted signalling ligands in fetal and maternal cell types of the six-species phylogeny, coded as two binary states for fetal and maternal expression, respectively. Percentages are normalized by row. e, Volcano plot showing co-evolutionary coupling of ligand and receptor expression magnitude. Two-sided P values testing whether the slope of phylogenetically independent contrasts between ligand and receptor differs significantly from zero are plotted on the vertical axis, and ordinary least squares regression slopes of zTPM expression values of ligand and receptor are plotted on the horizontal axis. Pairs with strong evolutionary coupling fall into the shaded orange (negative correlation) and green (positive correlation) regions, and those with stronger statistical support are plotted in red. The blue dashed line marks a P value cutoff of 0.05, whereas the green dashed line marks a Bonferroni-adjusted P value cutoff of 0.05/npairs tested. f, Inferred evolutionary changes to ligand and corresponding receptor expression in humans with respect to the human–macaque common ancestor (Catarrhini). Silhouettes from PhyloPic under a Creative Commons licence: human, NASA (PDM 1.0); tenrec, Yan Wong (CC0 1.0); macaque, Jane Whitehouse (CC0 1.0); mouse, Michael Keesey (PDM 1.0).
