Low Genetic Variation of Red-crowned Cranes on Hokkaido Island, Japan, Over the Hundred Years

The red-crowned crane (Grus japonensis) is recognized internationally as an endangered species. Migratory populations breed in eastern Russia and northeastern China, whereas the resident population inhabits the island of Hokkaido, Japan. Although the population inhabiting Hokkaido had experienced a severe bottleneck by the end of the 19th century, the population size has recovered to about 1500 and continues to increase now thanks to conservation efforts. A previous study reported that no marked genetic differences were seen in the island population, and that the genetic variation of the whole population on Hokkaido was lower than that of the continental population. However, the precise genetic structure of the island population in the past or near present remains unclear. To better understand the spatiotemporal changes in the genetic structure of the island population, we performed mitochondrial DNA (mtDNA) analyses using stuffed specimens (years 1878-2001) and tissue or blood samples (years 1970-2014). We found three haplotypes in the island population, one of which was a novel mtDNA haplotype in 1997 and 2007 samples. In addition, there was no clear difference in the haplotype frequency through the time span. These results suggest that the low genetic variation of the island population persisted for the last hundred years. It is thus nearly impossible for the island population to recover its genetic variation in isolation. Conservation plans for this species should therefore include the promotion of genetic exchanges between the continental and island populations, such as through artificial introduction to Hokkaido

Large-Scale Survey of Mitochondrial D-Loop of the Red-Crowned Crane Grus japonensis in Hokkaido, Japan by Convenient Genotyping Method

The Red-crowned Crane, Grus japonensis, is an endangered species of crane that has two separate breeding populations, one in the Amur River basin (continental population) and the other in eastern or northern Hokkaido, Japan (island population). So far, only two haplotypes (Gj1 and Gj2) have been identified in the mitochondrial D-loop in island population, whereas seven haplotypes have been found in continental population (Gj3-Gj9). We developed a rapid and inexpensive method of extensive genotyping of D-loop haplotypes in Red-crowned Cranes, based on amplification refractory mutation system (ARMS) PCR assay. Two hundred and three cranes in eastern Hokkaido were studied with this method and supplemental DNA sequencing. Only two haplotypes, Gj1 and Gj2, were confirmed in eastern Hokkaido with Gj2 as a major haplotype. Additionally, only Gj2 was identified in twelve feathers from both sexes found in northern Hokkaido. These results suggest scarce genetic diversity in island population of Red-crowned Cranes in Hokkaido, Japan

Origin of a pair of red-crowned cranes (Grus japonensis) found in Sarobetsu Wetland, northwestern Hokkaido, Japan: a possible crossbreeding between the island and the mainland population

Red-crowned cranes Grus japonensis, which are an endangered species, have two separate populations, a mainland population in the Eurasian continent and an island population in eastern Hokkaido, Japan. Island cranes showed three haplotypes (Gj1, Gj2 and Gj13), whereas ten haplotypes (Gj3–Gj12) were confirmed in captive cranes and stray cranes. We found Gj5 haplotype in feathers of two cranes as well as four new haplotypes in seven wild crane feathers collected in South Korea. We also found feathers in the nest in Sarobetsu Wetland in northwestern Hokkaido. While the haplotype of female-derived feathers was Gj2, that of male-derived feathers was Gj5. The results suggest that there has been crossbreeding between cranes in the island population and cranes in the mainland population