Two opposite phenomena have been found in territorial animals, the "dear enemy'' and the ''nasty neighbour'', which refer to individuals that show less aggression toward neighbours than toward strangers and vice versa. However, the need to maintain territory should differ for males and females because sexual reproduction is the result of the different adaptive strategies of the sexes. In this study, we explore territorial behaviour in the context of dear-enemy and nasty neighbour effects in the Mexican volcano mouse (Neotomodon alstoni). Patterns of spatial relationships between individuals and the degrees of agonistic behaviour among neighbours were analysed for a period of one year. Results exhibit a greater spatial proximity between male pairs during the non-reproductive period than during the reproductive period, and greater spatial proximity between pairs of females during the reproductive period than during the non-reproductive period. The analysis of agonistic behaviour showed that there is less tolerance for distant neighbours than for nearest neighbours. However, there is a greater frequency of aggression between male pairs than between females, while females appear to exhibit non-aggressive avoidance among individuals. The results support the theory that Mexican volcano mouse exhibits the "dear enemy phenomenon".

中文翻译：

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墨西哥火山鼠 Neotomodon alstoni 中的亲爱敌人效应：性别对邻居间对抗行为的影响

与非生殖期相比，生殖期雌性成对之间的空间接近度更大。对激动行为的分析表明，远邻的容忍度低于最近的邻居。然而，男性对之间的攻击频率高于女性之间，而女性似乎在个体之间表现出非攻击性的回避。结果支持了墨西哥火山鼠表现出“亲爱的敌人现象”的理论。男性对之间的攻击频率高于女性之间，而女性似乎在个体之间表现出非攻击性的回避。结果支持了墨西哥火山鼠表现出“亲爱的敌人现象”的理论。男性对之间的攻击频率高于女性之间，而女性似乎在个体之间表现出非攻击性的回避。结果支持了墨西哥火山老鼠表现出“亲爱的敌人现象”的理论。