2025-04-25 九州大学
左:アズキゾウムシの親。 右:環境変化にさらされると雄卵(息子)を大きく産んだ。(スケール:0.5 mm)
<関連情報>
- https://www.kyushu-u.ac.jp/ja/researches/view/1257
- https://www.kyushu-u.ac.jp/f/61578/25_0425_03.pdf
- https://www.nature.com/articles/s41598-025-96680-6
ウォルバキア感染により、環境変化に適応した雄の卵サイズの増大が促進される Wolbachia infection facilitates adaptive increase in male egg size in response to environmental changes
Eloïse Leroy,Siyi Gao,Maya Gonzalez,Marie-Pierre Ellies-Oury & Midori Tuda
Scientific Reports Published:16 April 2025
DOI:https://doi.org/10.1038/s41598-025-96680-6
Abstract
Under challenging conditions such as maladapted biotic and abiotic conditions, females can plastically adjust their egg size (gamete or zygote size) to counteract fitness declines early in life. Recent evidence suggests that endosymbionts may enhance this egg-size plasticity. Possible endosymbionts’ modification of impact of multiple stressors is not well explored. Therefore, this study aims to test (1) whether Wolbachia infection influences the plasticity of parental investment in egg size under suboptimal environmental conditions and (2) whether the plasticity depends on the sex of eggs. We used three lines of the azuki bean beetle (Callosobruchus chinensis): a line coinfected with the wBruCon and wBruOri Wolbachia strains, a cured line infected solely with the wBruCon, and an uninfected (cured) line. These lines were subjected to either a control environment or a simulated climate change environment (elevated temperature and carbon dioxide levels, eT&CO2) to examine Wolbachia infection effects on parental investment in their offspring (egg size) and its subsequent impact on offspring fitness, including survival, development, and adult lifespan under starvation. After two days of eT&CO2 exposure, coinfected parents increased male egg size only. Larger eggs developed faster in both sexes and exhibited higher survival. However, offspring adult lifespan was not influenced by egg size but by environment, sex, Wolbachia infection, and development time: eT&CO2 reduced male lifespan but not female lifespan, the singly-infected line females lived longer than coinfected and uninfected line females, and shorter development time linked to longer lifespan. The negative correlation between development time and lifespan was higher under eT&CO2 but not sex-specific. This study is the first to demonstrate sex-specific egg size plasticity associated with Wolbachia infection in species with sex determination systems other than haplodiploid.
