Fig. 3
From: Genes underlying the evolution of tetrapod testes size
Significant relationships between molecular adaptation and testes mass across tetrapods for five of the twelve studied target genes. The relationship between testes mass and RdN (a) is significantly positive for Alkbh5 (the proportion of the parameter crossing zero, px = 0.046) and negative for Pld6 (px = 0.002). The relationship between Rphen and RdN (c) is significant for all five genes (px = 0.043 for Alkbh5; px = 0.036 for Dmrtb1; px = 0.006 for Nlrp3; px = 0.033 for Pld6; px = 0.048 for Sp4). In both models, RdS is included as a covariate, which is always larger than RdN (b) in line with expectations, e.g. [28]. Whilst RdS is not significantly associated with testes mass for any gene (not shown), it is significantly associated with Rphen for three genes (d): positively in both Alkbh5 (px < 0.001) and Pld6 (px = 0.001) and negatively for Nlrp3 (px = 0.001)