Data from: Variation in growth of Damaraland mole-rats is explained by competition rather than by functional specialization for different tasks

In some eusocial insect societies, adaptation to the division of labour results in multimodal size variation among workers. It has been suggested that variation in size and growth among non-breeders in naked and Damaraland mole-rats may similarly reflect functional divergence associated with different cooperative tasks. However, it is unclear whether individual growth rates are multimodally distributed (as would be expected if variation in growth is associated with specialization for different tasks) or whether variation in growth is unimodally distributed, and is related to differences in the social and physical environment (as would be predicted if there are individual differences in growth but no discrete differences in developmental pathways). Here, we show that growth trajectories of non-breeding Damaraland mole-rats vary widely, and that their distribution is unimodal, contrary to the suggestion that variation in growth is the result of differentiation into discrete castes. Though there is no evidence of discrete variation in growth, social factors appear to exert important effects on growth rates and age-specific size, which are both reduced in large social groups.在部分真社会性（eusocial）昆虫社群中，对劳动分工的适应使得工职个体间产生多峰体型变异。有研究提出，裸鼹鼠（naked mole-rat）与达马拉兰鼹鼠（Damaraland mole-rat）的非繁殖个体间的体型与生长差异，同样可能反映出与不同合作任务相关的功能分化。但目前仍存在两个尚未明确的问题：一是个体生长速率是否呈多峰分布（若生长变异与不同任务的特化相关，则该分布模式符合预期）；二是生长变异是否为单峰分布，且与社会及物理环境的差异相关（若个体间仅存在生长量的连续差异，而发育通路无明确分化，则该模式为预期结果）。本研究显示，达马拉兰鼹鼠非繁殖个体的生长轨迹（growth trajectory）存在广泛差异，但其分布呈单峰模式，这与‘生长变异源于不同离散社会品级分化’的假说相悖。尽管未发现生长存在离散变异的证据，但社会因素似乎对生长速率及年龄对应体型（age-specific size）具有重要影响：在大型社会群体中，这两项指标均会降低。