2025-04-24 マックス・プランク研究所
© Fragkiskos Darmis
マックス・プランク進化生物学研究所の研究チームは、野生のハツカネズミ(Mus musculus)のオスが採用する2つの異なる繁殖戦略を明らかにしました。一部のオスは縄張りを守り、メスを引き寄せる「防衛型」、他のオスは広範囲を移動し、交尾の機会を探す「遊撃型」として行動します。これらの戦略は遺伝的に固定されたものではなく、個体の体格、年齢、社会的環境に応じて柔軟に変化します。例えば、大型のオスは縄張りを維持しやすいものの、競争が激化すると遊撃型に転じることがあります。また、遊撃型のオスは精巣が大きく、短期間の交尾での成功率を高める生理的適応が見られました。この研究は、動物の繁殖行動が環境や個体の状態に応じて動的に変化することを示し、行動生態学や進化生物学の理解を深めるものです。
<関連情報>
- https://www.mpg.de/24600345/0424-limn-wild-house-mice-reveal-secret-love-lives-fighters-vs-153345-x
- https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.70039
ハツカネズミの雄の繁殖戦術: 一貫した個体差、内在的要因、密度効果 Male reproductive tactics in house mice: Consistent individual differences, intrinsic factors and density effects
Fragkiskos Darmis, Alexandros Vezyrakis, Anja Guenther
Journal of Animal Ecology Published: 12 April 2025
DOI:https://doi.org/10.1111/1365-2656.70039
Abstract
- Alternative reproductive tactics (ARTs) describe non-reversible or flexible alternative strategies that secure fertilization. For example, some male defend territories with females while others attempt sneaky matings. Often, ARTs are considered to be status-dependent and are explained by differences in mass or competitive ability. However, most studies on ARTs only approximate their fitness effect, ignore males that never reproduced and consider status (e.g. weight) as the sole mediator of ARTs.
- We used 244 male mice, Mus musculus domesticus, from semi-natural populations, to describe ARTs in Mus Musculus for the first time. We followed males throughout their life and categorized them as territorials or roamers over multiple monthly intervals, after validating our method of assigning tactics with detailed spatial data.
- We explored if tactic choice is repeatable, whether multiple social and/or intrinsic factors predict tactic choice and transitions between tactics, and tested for fitness and physiological differences between ARTs.
- Tactic choice was repeatable, but males switched flexibly between tactics. Tactic choice was associated with mass, age, the operational sex ratio and population size. Territorials had a higher probability of reproduction, but a lower gonadosomatic index.
- Our results reveal a personality component of ARTs, confirm equal mean fitness among tactics and suggest tactic choice as a multifaceted decision under various selective pressures.
