Cahan Sara Helms, Julian Glennis E, Rissing Steven W, Schwander Tanja, Parker Joel D, Keller Laurent
Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
Curr Biol. 2004 Dec 29;14(24):2277-82. doi: 10.1016/j.cub.2004.12.027.
Caste differentiation and reproductive division of labor are the hallmarks of insect societies. In ants and other social Hymenoptera, development of female larvae into queens or workers generally results from environmentally induced differences in gene expression. However, several cases in which certain gene combinations may determine reproductive status have been described in bees and ants. We investigated experimentally whether genotype directly influences caste determination in two populations of Pogonomyrmex harvester ants in which genotype-caste associations have been observed. Each population contains two genetic lineages. Queens are polyandrous and mate with males of both lineages , but in mature colonies, over 95% of daughter queens have a pure-lineage genome, whereas all workers are of F1 interlineage ancestry. We found that this pattern is maintained throughout the colony life cycle, even when only a single caste is being produced. Through controlled crosses, we demonstrate that pure-lineage eggs fail to develop into workers even when interlineage brood are not present. Thus, environmental caste determination in these individuals appears to have been lost in favor of a hardwired genetic mechanism. Our results reveal that genetic control of reproductive fate can persist without loss of the eusocial caste structure.
种姓分化和生殖分工是昆虫社会的标志。在蚂蚁和其他社会性膜翅目昆虫中，雌性幼虫发育成蚁后或工蚁通常是由环境诱导的基因表达差异导致的。然而，在蜜蜂和蚂蚁中已经描述了一些特定基因组合可能决定生殖状态的情况。我们通过实验研究了基因型是否直接影响收获蚁属的两种收获蚁种群的种姓决定，在这两种收获蚁中已经观察到基因型与种姓的关联。每个种群包含两个遗传谱系。蚁后是多雄受精的，与两个谱系的雄蚁交配，但在成熟蚁群中，超过95%的雌性后代蚁后具有纯谱系基因组，而所有工蚁都是F1代谱系间杂交的后代。我们发现，即使只产生一种蚁型，这种模式在整个蚁群生命周期中都得以维持。通过控制杂交，我们证明即使没有谱系间杂交的幼虫，纯谱系的卵也无法发育成工蚁。因此，这些个体中由环境决定种姓的现象似乎已经消失，转而支持一种固定的遗传机制。我们的研究结果表明，生殖命运的遗传控制可以持续存在，而不会丧失群居性昆虫的种姓结构。
