Data from: Using playback of territorial calls to investigate mechanisms of kin discrimination in red squirrels

Kin recognition can facilitate kin selection and may have played a role in the evolution of sociality. Red squirrels (Tamiasciurus hudsonicus) defend territories using vocalizations known as rattles. They use rattles to discriminate kin, though the mechanism underlying this ability is unknown. Our objective was to distinguish between the mechanisms of prior association, where animals learn the phenotypes of kin they associate with early in life, and phenotype matching/recognition alleles, where animals use a template to match phenotypes, thereby allowing them to recognize kin without an association early in life. We used audio playbacks to measure the responses of squirrels to rattles from familiar kin, unfamiliar kin, and non-kin. Initial analyses revealed that red squirrels did not discriminate between familiar and unfamiliar kin, but also did not discriminate between kin and non-kin, despite previous evidence indicating this capability. Post-hoc analyses showed that a squirrel’s propensity to rattle in response to playback depended on an interaction between relatedness and how the playback stimuli had been recorded. Red squirrels discriminated between rattles from close kin (r = 0.5) and rattles from non-kin (r < 0.5) when the rattles were recorded from provoked squirrels. Squirrels did not exhibit kin discrimination in response to rattles that had been recorded from unprovoked squirrels. Once we accounted for how the stimuli had been recorded, we found no difference in the responses to familiar and unfamiliar kin. Our study suggests that kin discrimination by red squirrels may be context-dependent.亲缘识别（kin recognition）可助力亲缘选择（kin selection），并可能在社会性（sociality）的演化进程中发挥了重要作用。美洲红松鼠（*Tamiasciurus hudsonicus*）通过名为摇鸣（rattles）的鸣叫声保卫领地，且借助该鸣叫声实现亲缘识别，但这一能力背后的具体机制仍不明确。本研究旨在区分两种潜在机制：其一为预先关联机制，即动物在生命早期习得与之共处的亲缘个体的表型特征；其二为表型匹配/识别等位基因（phenotype matching/recognition alleles）机制，即动物通过构建匹配模板比对表型，从而无需在早期建立关联即可识别亲缘个体。本研究采用音频回放实验，测定红松鼠对熟悉亲缘、陌生亲缘以及非亲缘个体所发出摇鸣的反应。初步分析结果显示，尽管已有研究表明红松鼠具备亲缘识别能力，但它们既未区分熟悉亲缘与陌生亲缘，也未区分亲缘个体与非亲缘个体。事后检验分析显示，红松鼠在回放实验中发出摇鸣的倾向，取决于亲缘关系远近与回放刺激录制方式之间的交互效应。当摇鸣录自由受激红松鼠发出时，红松鼠能够区分亲缘系数r=0.5的近缘个体与r<0.5的非亲缘个体所发出的摇鸣；而当摇鸣录自未受激红松鼠时，红松鼠则未表现出亲缘识别行为。在控制刺激录制方式这一变量后，我们未发现红松鼠对熟悉亲缘与陌生亲缘的反应存在显著差异。本研究表明，美洲红松鼠的亲缘识别行为可能具有情境依赖性。