Contributions of molecular and cranial specializations for sensory adaptation in the subterranean blind mole rats (Nannospalax xanthodon)

The blind mole rats which have adapted excellently to subterranean life, exhibit remarkable navigation abilities despite structural regression in their visual systems and decline in auditory functions. This study investigates the sensory capabilities enabling blind mole rat possible adaptation to dark environments through gene expression analyses, evolutionary sequence comparisons, and cranial morphometric examinations. Comparative analyses reveal a significant reduction in the expression of genes related to vision (Pax6, Impg) and hearing (Coch, Necap1) in subterranean blind mole rat Nannospalax xanthodon compared to surface dwelling Rattus rattus. In contrast, genes associated with sound perception (Foxp2, Bmp7, Kcnq4, Tmc1) show a significant increase in expression. These findings indicate that sensory losses are aligned with the classical model observed in species that compensate for sensory deficits through echolocation. Remarkably, the gene expression profiles of N. xanthodon show similarities to those of mammals with highly developed echolocation abilities, revealing common molecular patterns between seismic and ultrasonic echolocation. Phylogenetic analyses of echolocation related genes show that blind mole rats share specific amino acid motifs with certain echolocating bat and whale species. Notably, positive selection signal observed in the Kcnq4 gene suggest that this gene may play a critical role in seismic vibration detection. Cranial morphometry studies support the notion that N. xanthodon possess not only putative morphological adaptations specific to their digging lifestyle but also specialized anatomical structures for detecting seismic vibrations. This study provides contributions to understanding the sensory adaptation of subterranean mammals and evaluates blind mole rats in this context for the first time.