Institute of Evolutionary Biology and Environmental Studies, Department of Animal Behaviour, University of Zurich, Winterthurerstr, 190, 8057 Zurich, Switzerland.
Front Zool. 2010 Jun 23;7:19. doi: 10.1186/1742-9994-7-19.
Territoriality functions to monopolize access to resources including mates, but is costly in terms of energy and time investment. Some species reduce these costs by being less aggressive towards their neighbours than towards unfamiliar strangers, the so called dear enemy phenomenon. However, in other species individuals are more, not less aggressive towards their neighbours. It has been hypothesised that this is due to the fact that neighbours can impose a greater threat than strangers, but this has not been tested previously.
We tested aggression in wild group-living male striped mice in a neutral test arena and demonstrate that breeders are more aggressive than non-breeding philopatrics, and that more aggression occurs during the breeding than during the non-breeding season. Male breeders were significantly more aggressive towards their neighbours than towards strangers, leading to the prediction that neighbours are the most important competitors for paternity. Using a molecular parentage analysis we show that 28% of offspring are sired by neighbouring males and only 7% by strangers.
We conclude that in male striped mice the main function of male aggression is defending paternity against their territorial neighbours.
领地行为有助于垄断包括配偶在内的资源获取，但这会在能源和时间投入方面带来代价。一些物种通过对邻居的攻击性比对陌生陌生人的攻击性要小，从而降低这些成本，这就是所谓的“亲爱的敌人现象”。然而，在其他物种中，个体对邻居的攻击性更强，而不是更弱。有人假设，这是因为邻居可能比陌生人构成更大的威胁，但这尚未得到验证。
我们在一个中立的测试场地中测试了野生群居雄性条纹鼠的攻击性，结果表明，繁殖者比非繁殖的居群者更具攻击性，而且在繁殖季节比非繁殖季节攻击性更强。雄性繁殖者对邻居的攻击性明显高于对陌生人的攻击性，这表明邻居是父权竞争的最重要竞争者。通过分子亲子分析，我们发现有 28%的后代是由邻居雄性所生育，而只有 7%是由陌生人所生育。
我们得出结论，在雄性条纹鼠中，雄性攻击性的主要功能是保护其领地邻居的父权。
