Fig. 3

Ecological factors influencing the evolution of the OLF gene repertoire in ray-finned fishes. a, b Effect size distribution of several ecological traits on the number of OLF genes, showing highest density intervals (HDI) of 80% (black) and 95% (grey). Colours delimit related factors containing exclusive sets of species. Statistical significance (95% HDI does not include 0) is marked with an asterisk (Additional file 2: Table S4-S6). c Density plot with the number of OLF genes in non-exclusive ecological groups (freshwater, n = 125; amphibious, n = 19; nocturnal, n = 62), plus a subset of fishes presenting the three aforementioned traits (FAN, n = 9). d Differences in the OLF repertoire size between nocturnal (n = 11) and diurnal (n = 8) amphibious fishes. Posterior probability (pp) of nocturnal being higher than diurnal is indicated. e Number of genes for each receptor family identified in our genome assembly of Channallabes apus (C. apus), compared to other Siluriformes (Sil.; n = 9) and teleosts (Tel.; n = 195). f Left, picture of C. apus showing the position of the olfactory epithelium (OE) and the four types of barbels: nasal, maxillary (Max), mandibular outer (MO) and mandibular inner (MI). Right, number of RNA-seq reads per million (PM) from barbels and OE mapped to annotated OLF genes in C. apus (SD shown). g PGLS model showing a significant correlation between the number of OLF genes and the covariance in the number of OB and other brain cells (Additional file 2: Table S7) in twenty-four species (x-axis is log-transformed). h Significantly higher proportion of OB cells in FAN species (n = 6) compared to the other fish species (n = 18) after phylogenetic and brain size correction