Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine of Vienna, Vienna, Austria.
PLoS One. 2012;7(2):e32806. doi: 10.1371/journal.pone.0032806. Epub 2012 Feb 29.
An individual's investment in mating or keeping a pair bond intact may be influenced not only by the attractiveness of its current mate, but also by that of other potential mates. In this study, we investigated the effect of relative attractiveness on pair-bond behaviour in bearded reedlings, Panurus biarmicus. We showed that mate attractiveness, in terms of beard length in males and tail length in females, influenced courtship behaviour when the pair was kept isolated. In the presence of a conspecific, contact initiations within a pair increased. This increment was mainly related to the sex of the unpaired conspecific, however, and less to differences in attractiveness between the current partner and the unpaired conspecific. Female contact initiations towards potential extra mates were independent of male attractiveness, whereas male contact behaviour was significantly influenced by female attractiveness. However, females displayed more contact initiations to their current mate when they were less attractive than the unpaired females. Males decreased their overtures towards other females with increasing attractiveness of their current mates. Overall, our results suggested that, when there was a risk of losing their mate, bearded reedlings adjust their pair-bond investment mainly in response to the presence or absence of a competitor, and fine-tune investment to a lesser extent in response to the attractiveness of that potential competitor.
个体在交配或维持伴侣关系方面的投入不仅受到当前伴侣吸引力的影响，还受到其他潜在伴侣吸引力的影响。在这项研究中，我们调查了相对吸引力对须苇鹀（Panurus biarmicus）的伴侣行为的影响。我们发现，以雄鸟的胡须长度和雌鸟的尾长来衡量，伴侣的吸引力影响了将配对隔离时的求偶行为。当有同种个体存在时，对配对内的接触会增加。然而，这种增加主要与未配对同种个体的性别有关，而与当前伴侣和未配对同种个体之间的吸引力差异关系较小。雌鸟对潜在额外伴侣的接触发起与雄鸟的吸引力无关，而雄鸟的接触行为则受到雌鸟吸引力的显著影响。然而，当雌性比未配对的雌性吸引力差时，它们对当前伴侣的接触发起会更多。雄性会随着当前伴侣吸引力的增加而减少对其他雌性的主动求爱。总的来说，我们的研究结果表明，当面临失去伴侣的风险时，须苇鹀主要通过有无竞争对手来调整其伴侣关系的投资，而在一定程度上通过调整对潜在竞争对手的吸引力来微调投资。
