Conventional Gel Electrophoresis-Resolvable Insertion/Deletion Markers for Individual Identification and Analysis of Population Genetics in Red-Crowned Cranes in Eastern Hokkaido, Japan.

Abstract

Simple SummaryThe red-crowned crane is an endangered bird species in the Far East Eurasian continent and Hokkaido, Japan. Individual identification has been achieved with banding and installed transmitters in only a few cranes, though individual identification is essential for various assessments of cranes on their behavioral characteristics, for example. An insertion/deletion (InDel) mutation is a mutation ranging from 1 to 50 bp and is very useful for genetic studies. If primer sets across InDels (>20 bp) can be designed, an InDel polymorphism can be determined with conventional agarose gel electrophoresis, as reported in some plant species. We found a sufficient number of InDel primer sets to be used for individual identification and analysis of population genetics of red-crowned cranes in Hokkaido. The method has additional advantages, such as convenience and low cost, without sequencing and an expensive apparatus.Red-crowned crane Grus japonensis is an endangered species in two separate populations: the mainland population in the Eurasian continent and the island population in eastern Hokkaido, Japan. We found 11 insertion/deletion (InDel) markers in the genome of the red-crowned crane and designed primer sets across these InDels that can be analyzed with conventional agarose gel electrophoresis. Sixty-six samples of whole blood and skeletal muscle obtained from red-crowned cranes, including 12 families in eastern Hokkaido from 1994 to 2021, showed different patterns in gel images of 11 InDel PCR reactions except for two pairs. The combined non-exclusion probability of the 11 markers indicates that individuals can be determined with a probability of 99.9%. In 39 non-relative chicks, the expected heterozygosity (He) was 0.316, suggesting low genetic diversity. This might not be caused by high levels of inbreeding since the average FIS was not significantly different from zero (0.095, p = 0.075). The results suggest that the 11 InDel primer sets can be used for fairly accurate individual identification as well as genetic population analyses in red-crowned cranes in the island population.