Data from: Variation in growth of Damaraland mole-rats is explained by competition rather than by functional specialisation 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 specialisation 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.在部分真社会性昆虫（eusocial insect）社会中，对劳动分工的适应会引发工职个体间的多峰体型变异。有研究推测，裸鼹鼠（naked mole-rat）与达马拉兰鼹形鼠（Damaraland mole-rat）的非繁殖个体在体型与生长层面的差异，或许同样体现了与不同合作任务相关的功能分化。但目前仍存在两个未明确的问题：一是个体生长速率是否呈多峰分布（若生长差异与不同任务的特化行为相关，则该分布模式符合预期）；二是生长差异是否为单峰分布，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，而发育通路无离散分化，则该模式符合预测）。本研究证实，达马拉兰鼹形鼠的非繁殖个体的生长轨迹存在显著的广泛差异，且其分布呈单峰态势，这与“生长差异源于离散品级分化”的假说相悖。尽管未观测到生长存在离散差异的证据，但社会因素似乎对生长速率与年龄特异性体型具有关键调控作用：二者在大型社会群体中均会出现显著降低。