Recent transitions in genetic diversity and structure in the endangered semi‐natural grassland butterfly, Melitaea protomedia, in Japan

Abstract

Abstract The monitoring of genetic characters and definition of effective conservation units are important for conservation of endangered semi‐natural grassland species. Using molecular markers, we elucidated the recent transitions in genetic diversity for the endangered grassland butterfly Melitaea protomedia (Lepidoptera; Nymphalidae) in Japan. First, we examined changes in genetic diversity and structure from the 1980s to the 2010s from archival and contemporary DNA samples using eight microsatellite markers. Second, we estimated the genetic structure based on 1374 bp of mitochondrial COI gene from contemporary samples. We also defined the conservation units of M. protomedia based on the above analysis. The genetic diversity of M. protomedia has significantly declined from the 1980s to the 2010s. Although genetic differentiation was very strong among populations in c. 2010, there was only weak genetic structure in c. 1990. In addition, the number of haplotypes based on mitochondrial DNA is now very low due to recent declines. These findings suggest that effective conservation units for critically endangered species should be determined based on historic (i.e. prior to population declines) as well as contemporary genetic diversity and differentiation, because genetic structure may have changed over time. Genetic analysis of archival DNA is useful to obtain historic genetic information.