Investment in signalling is subject to multiple trade-offs that vary with life-stage, leading to a complex relationship between survival and trait expression. We show a negative relationship between survival and song rate in response to simulated territorial intrusion in male banded wrens (Thryophilus pleurostictus), and test several explanations for this association. (1) Male age failed to explain the association: though age affected song rate in a cross-sectional analysis, longitudinal analysis showed that individuals did not increase their song rate as they got older. Reconciling these results suggests differential selection against young males that respond to intrusion with low song rates. (2) Mortality costs of high song rates did not appear to explain the negative relationship between song rate and survival because, though song rate in response to playback was condition-dependent, high song rates in a different context did not appear to impose mortality costs. (3) High levels of territorial pressure may have increased mortality, but were not associated with high song rates in response to playback. (4) Since song rates did not increase with age, but tended to increase only in the last year of life, we tentatively suggest that the negative relationship between song rate and survival could represent a terminal investment in territorial defence by males in their final breeding season, though further work is needed to confirm this conclusion.

中文翻译：

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在死亡面前歌唱：雄性鹪鹩在最后一个繁殖季节唱歌更多

对信号的投资受制于随着生命阶段而变化的多种权衡，导致生存和特征表达之间的复杂关系。我们在雄性带状鹪鹩 (Thryophilus pleurostictus) 模拟领土入侵时显示存活率和歌曲率之间存在负相关，并测试了对这种关联的几种解释。(1) 男性年龄无法解释这种关联：尽管在横断面分析中年龄会影响歌曲率，但纵向分析表明，随着年龄的增长，个体的歌曲率并没有增加。调和这些结果表明对以低歌曲率响应入侵的年轻男性的差异选择。(2) 高歌曲率的死亡率似乎并不能解释歌曲率和存活率之间的负相关关系，因为，尽管响应播放的歌曲率取决于条件，但不同环境下的高歌曲率似乎不会造成死亡成本。(3) 高水平的领土压力可能会增加死亡率，但与响应播放的高歌曲率无关。(4) 由于鸣声率不随年龄增长而增加，而仅在生命的最后一年才增加，我们初步认为，鸣声率与存活率之间的负相关可能代表雄性在最终繁殖中对领土防御的最终投资季节，尽管需要进一步的工作来证实这一结论。但与响应播放的高歌曲率无关。(4) 由于鸣声率不随年龄增长而增加，而仅在生命的最后一年才增加，我们初步认为，鸣声率与存活率之间的负相关可能代表雄性在最终繁殖中对领土防御的最终投资季节，尽管需要进一步的工作来证实这一结论。但与响应播放的高歌曲率无关。(4) 由于鸣声率不随年龄增长而增加，而仅在生命的最后一年才增加，我们初步认为，鸣声率与存活率之间的负相关可能代表雄性在最终繁殖中对领土防御的最终投资季节，尽管需要进一步的工作来证实这一结论。