Bees Change Behavior to Adapt to High Altitudes

• A study reveals that adaptation to high altitudes in bees results from behavioral differences rather than morphological differences
• The genes involved in high-altitude adaptation in bees are related to feeding behavior

An Asian bee pollinates a plant from the Brassicaceae family (Crucifers). Author: Tetsuya Shimizu.

Honeybees living at high altitudes are larger, darker, and have longer body hair compared to bees from lower altitudes.

However, these differences do not appear to be due to genes related to morphology or pigmentation, but rather to genes associated with behavior and feeding, according to a study involving researchers from the Spanish National Research Council (CSIC), published in the journal 'Molecular Ecology'.

For the study, the researchers explored DNA differences between populations of Asian honeybees (Apis cerana) from high and low altitudes in the Yunnan province (China).

"We used different bioinformatics programs to scan the genomes of these bees and identified several regions that seem to be favored by natural selection in the high-altitude bees", explains Santiago Montero-Mendieta, a predoctoral researcher at the CSIC in the Doñana Biological Station.

Previous studies had linked the high-altitude adaptation of African honeybees (Apis mellifera) to two mutations affecting the order of certain genes on chromosomes 7 and 9. Some of these genes are related to feeding behavior, which could indicate that food abundance and distribution are key factors for adaptation to high-altitude habitats in bees.

However, the results of this study now indicate that Asian bees living at high altitudes do not exhibit such chromosomal rearrangements in their genomes. Therefore, it is suggested that these mechanisms are not essential for bees to adapt to high-altitude environments.

"In our study with Asian bees, we did not find differences in genes associated with morphology or pigmentation, and these genes were also not observed in African bees", adds Montero-Mendieta.

An Apis cerana worker collects pollen from a red Passiflora sp. (Passifloraceae) in Yunnan, China. Author: Nicolas Vereecken.

Improvement of Learning

"We have identified signals of selection in genes potentially related to the improvement of olfactory learning and the ability to remember the location of food sources. We believe these improvements could be crucial for bees living at high altitudes, as resource availability in these areas is generally lower", explains Montero-Mendieta.

Therefore, he asserts that while the adaptation to high-altitude habitats in Asian bees has a different genetic basis than in African bees, researchers believe that selection might be occurring for genes with similar functions in both species.

According to CSIC, the results of this research will be extremely useful for monitoring Asian bee populations and establishing conservation priorities. "The pollination services provided by bees are essential for food production worldwide", comments Matthew T. Webster, a researcher at Uppsala University (Sweden) who led the study. "But unfortunately, Asian bee populations in China have been declining since the early 20th century due to changes in agricultural practices and the introduction of non-native bees," he adds.

Therefore, the researcher considers it important to understand how populations of this species adapt to different environmental conditions, such as altitude, as this can help improve conservation efforts and their management.

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Original publication:

Montero-Mendieta, S.*, Tan, K.*, Christmas, M.J., Olsson, A., Vilà, C., Wallberg, A., Webster, M.T. (2019). The genomic basis of adaptation to high-altitude habitats in the eastern honey bee (Apis cerana). Molecular Ecology, 28: 746–760. https://doi.org/10.1111/mec.14986

* These authors have made contributions that are considered equally significant, although the extent of this equality may be subject to various interpretations.