The Japanese honeybee is divided into three regional populations — Tohoku University clarifies whether anthropogenic migration inhibits local adaptation

Japanese honeybees were thought to be a genetically uniform population wherever they were found, however, a research group led by Graduate Student Takeshi Wakamiya (at the time of research, and currently Special Researcher of the Department of Biological Sciences at the Graduate School of Science at Tokyo Metropolitan University) and Professor Masakado Kawata (at the time of research, and currently President-Appointed Extraordinary Professor of Tohoku University) of the Graduate School of Life Sciences at Tohoku University have found that Japanese honeybees are divided into three genetically distinct regional populations throughout Japan: northern, central, and southern. It was also clear that they have adapted to the specific factors of each region. The artificial movement of bee colonies between regions could inhibit their adaptive status. These results were published in the journal Ecology and Evolution.

The research group performed high-resolution whole-genome analysis to reveal the population genetic structure of 105 Japanese honeybees from different regions of Japan. The results revealed that honeybee populations within the Japanese archipelago can be broadly divided into three regions: northern (Tohoku−Kanto−Chubu districts), central (Chugoku district), and southern (Kyushu district).

Based on the genetic composition of each individual, it was possible to determine which ones were likely artificially displaced and which were not. For example, individuals found in Fukushima were found to be southern in genetic composition. Subsequently, the researchers identified candidate genes related to local adaptation that have undergone natural selection (theory of evolution) in each of the three regions. Additionally, they detected candidate genes related to environmental adaptation that changed in frequency according to climatic variables along a north—south geographic gradient, such as temperature, snowfall, precipitation, and sunlight. They found that genes that are locally adapted to each region did not match genes that are adapted to the environments that varied along the latitude.

This suggests that Japanese honeybees are adapted to the unique environment of each region, making it difficult for them to move north in response to rising temperatures and other factors caused by global warming, which could increase the risk of population decline. The movement of individuals between different regions also suggests that the migrated individuals may not be able to adapt to the region to which they move. The evolutionary findings obtained in this study provide the basis for clarifying the detailed relationship between the genotypes of Japanese honeybees and their regional traits (characteristics of organisms).

Journal Information
Publication: Ecology and Evolution
Title: Genetic differentiation and local adaptation of the Japanese honeybee, Apis cerana japonica
DOI: 10.1002/ece3.10573