Ecology and Genetics Research Unit, Faculty of Science, University of Oulu, Post Box 8000, 90014, Oulu, Finland.
School of Biological Sciences, Monash University, Monash, VIC, 3800, Australia.
Oecologia. 2019 Oct;191(2):359-368. doi: 10.1007/s00442-019-04483-0. Epub 2019 Aug 31.
Successful territory defence is a prerequisite for reproduction across many taxa, and often highly sensitive to the actions of territorial neighbours. Nevertheless, to date, assessments of the significance of the behaviour of heterospecific neighbours have been infrequent and taxonomically restricted. In this field study, I examined the importance of both heterospecific and conspecific neighbours in a biparental fish, the convict cichlid, Amatitlania siquia. This was done by assessing the colonisation rates of vacant territories, the rates of aggression by the territory holders, and the overall rates of aggression towards intruders, in treatments that controlled the proximity of both neighbour types. Convict cichlid pairs colonised vacant nesting resources (territory locations) at similar rates independent of the proximity of heterospecific (moga, Hypsophrys nicaraguensis) or conspecific neighbours. However, a model of sympatric cichlid intruder was subjected to considerably higher overall levels of aggression when mogas were nearby. In contrast, the proximity of conspecifics did not have a significant effect on the overall aggression towards the intruder. These results suggest that previously demonstrated higher survival of convict cichlid broods in close proximity of mogas may be driven by aggression towards shared enemies. No conclusive evidence was found regarding whether mogas also influence convict cichlids' investment into anti-intruder aggression: the results show a marginally non-significant trend, and a moderately large effect size, to the direction of a lower investment in mogas', but not conspecifics', proximity. More generally, heterospecific neighbours may provide protective benefits in a wider range of ecological settings than commonly considered.
成功的领地防御是许多分类群繁殖的前提条件，而且通常对领地邻居的行为高度敏感。然而，迄今为止，对同种和异种种群邻居行为的重要性的评估仍然很少，并且受到分类限制。在这项实地研究中，我检查了在一种双亲鱼，即刚果慈鲷（Amatitlania siquia）中，异种种群和同种邻居的重要性。这是通过评估空缺领地的殖民化率、领地所有者的侵略率以及对入侵者的总体侵略率来实现的，这些评估在控制两种邻居类型的接近度的处理中进行。刚果慈鲷对空缺的筑巢资源（领地位置）的殖民化速度相似，而与异种种群（莫加，Hypsophrys nicaraguensis）或同种邻居的接近度无关。然而，当莫加在附近时，共生的慈鲷入侵者模型会受到更高的总体侵略水平。相比之下，同种个体的接近度对入侵者的总体侵略没有显著影响。这些结果表明，先前证明在莫加附近的刚果慈鲷幼鱼的生存率更高，可能是由于对共同敌人的侵略所致。没有确凿的证据表明莫加是否也会影响刚果慈鲷对入侵者的侵略投入：结果显示出一种略微非显著的趋势，以及一种中等大小的效应量，表明在莫加的接近度而不是同种个体的接近度上，投入的侵略性较低。更一般地说，异种种群邻居可能在比通常认为的更广泛的生态环境中提供保护益处。
