3.4 Positive selection in the macrotis group lineage
A total of 141 candidate PSGs and 1,274 positively selected sites were identified with signals of positive selection along each species branch of the macrotis group based on the branch-site model in PAML 4 (Figure 4, Table 2). Here, 7 hearing-related genes (CRYM ,FOXM1 , PYCARD , SLC52A2 , WRB , MAP6 , and SPRY2 ) (Table 3) showed significant evidence of positive selection in species of the macrotis group. And the positively selected sites tested in specieslow were species-specific and distinct from other species (Figure 4, Figure 5a - Figure 5f). This result may represent different adaptive responses of auditory development for specieslow. In particular, we found one hearing-related gene, SPRY2 , was positively selected inR. osgoodi , which emits normal echolocation frequency in themacrotis group. We found same amino acid mutation sites in four positively selected sites in SPRY2 for R. osgoodi andR. pusillus , which were different from other species (Figure 5g). The daily activities for bats mainly rely on acoustics, but five visually related PSGs (ARRDC3 , LZTFL1 , RAB8A ,EGFBPL1 , and TRNT1 ) were tested in specieslow (Table 4). No visual-related PSG was tested in speciesnormal.