Variability of bat nasal bone morphology found to determine ultrasonic localization

Japanese horseshoe bats—or nihon kikugashira—emit high-amplitude, ultrasonic waves from their nostrils. A number of ultrasound studies have previously attempted to disentangle significant regional variation in bat nasal shape without producing conclusive results.

Now, a research team led by Kyoto University has hit upon the possibility that this family of bat nasal bones may unlock the mystery of contrasting variation in echolocation. Researchers focused on Regional differences In the maximum dimension of Ultrasonic waves Excretions by rhinolophid bats for echolocation, as well as functional associations with morphological variation of the bat cranium.

Using 3D models of bat skulls – based on CT scans of museum specimens of Rhinolophus nippon and Rhinolophus cornutus – enabled the team to analyze morphometric variation. These specimens are endemic to East Asia, including Jeju Island and the Japanese Peninsula.

“Our results suggest that bat noses bone Site variations can affect speciation, leading to changes in morphology and ultrasonics — also known as the speech of rhinolophids, says first author Yugo Ikeda of the Kyoto University Museum.

Previous studies have pointed to a connection between the unique domed nasal bone and ultrasonics, which emit ultrasound from their noses, among the many traits of the Rhinolophidae family. However, smooth structures such as nasal swelling and brain matter in the bat nasal bone make variational analysis difficult to diagnose using two-dimensional images.

3D geometric morphometrics has become the standard for evaluating morphological changes in smooth structures. Using this technology enabled Ikeda’s team to show the relationship between nasal morphological variation and echolocation-related ultrasonic wave patterns between species and within species.

“The unique foraging mechanism of these bats is consistent with their evolutionary adaptation to the island environment,” Ikeda concluded.

There is paper. published In the journal Acta Chiropterologica.