Image acquisition
In this study, 11 native individuals and 20 hybrid individuals were used
(Supplementary Figures 1 and 2). The Hiroshima City Asa Zoological Park,
where these individuals are kept, has been researching and trying to
breed Japanese giant salamanders since 1971 and is one of the leading
facilities in Japan for research and conservation on this species.
Native individuals were already kept at the Japanese giant salamander
conservation and breeding facility. Hybrids were captured in the wild in
Hiroshima Prefecture in May 2022 and were kept in the same facility.
11 native individuals were photographed on August 20, 2022, at 11:00 AM.
Each individual was recorded for approximately 30 seconds using an
iPhone 11 with a 12-megapixel camera. We photographed the Japanese giant
salamanders in the water from above (Supplementary Figure 3). The videos
were converted to ten still JPEG images (1920 × 1080) per second using
the Free Video to JPG Converter.
20 hybrid individuals were photographed on November 19, 2022, at 2:00 PM
using an iPhone SE equipped with a 12-megapixel camera. The method of
image collection was the same as for the native individuals.