Data from: Clinal variation in colony breeding structure and level of inbreeding in the subterranean termites Reticulitermes flavipes and R. grassei

Social insects exhibit remarkable variation in their colony breeding structures, both within and among species. Ecological factors are believed to be important in shaping reproductive traits of social insect colonies, yet there is little information linking specific environmental variables with differences in breeding structure. Subterranean termites (Rhinotermitidae) show exceptional variation in colony breeding structure, differing in the number of reproductives and degree of inbreeding; colonies can be simple families headed by a single pair of monogamous reproductives (king and queen) or they can be extended families headed by multiple inbreeding neotenic reproductives (wingless individuals). Using microsatellite markers, we characterized colony breeding structure and levels of inbreeding in populations over large parts of the range of the subterranean termites Reticulitermes flavipes in the USA and R. grassei in Europe. Combining these new data with previous results on populations of both species, we found that latitude had a strong effect on the proportion of extended-family colonies in R. flavipes and on levels of inbreeding in both species. We examined the effect of several environmental variables that vary latitudinally; while the degree of inbreeding was greatest in cool, moist habitats in both species, seasonality affected the species differently. Inbreeding in R. flavipes was most strongly associated with climatic variables (mean annual temperature and seasonality), whereas nonclimatic variables, including the availability of wood substrate and soil composition, were important predictors of inbreeding in R. grassei. These results are the first showing that termite breeding structure is shaped by local environmental factors and that species can vary in their responses to these factors.社会性昆虫在同一物种内及不同物种间均展现出种群繁殖结构的显著多样性。尽管学界普遍认为生态因子是塑造社会性昆虫种群繁殖性状的关键因素，但目前仍鲜有研究能将特定环境变量与繁殖结构的差异建立明确关联。地下白蚁（鼻白蚁科Rhinotermitidae）的种群繁殖结构呈现出极高的多样性，差异体现在繁殖个体数量与近交程度两方面：其种群既可由一对单配制繁殖个体（蚁王与蚁后）统领的单一家族构成，也可由多只近交幼态繁殖个体（无翅个体）统领的扩展家族组成。本研究利用微卫星标记（microsatellite markers），对分布于美国的黄胸散白蚁（Reticulitermes flavipes）以及欧洲的格氏散白蚁（R. grassei）的大范围种群的繁殖结构与近交水平进行了表征。结合本次实验的新数据与两个物种此前的种群研究结果，我们发现纬度对黄胸散白蚁扩展家族种群的占比，以及两个物种的近交水平均具有显著影响。我们进一步分析了多个随纬度梯度变化的环境因子的影响：尽管两个物种的近交程度均在凉爽湿润的生境中达到最高，但季节节律对两个物种的影响存在差异。黄胸散白蚁的近交程度与气候因子（年平均温度及季节节律）关联最为紧密，而格氏散白蚁的近交水平则以非气候因子（如木质基质可获得性与土壤组成）作为重要预测因子。本研究结果首次证实，白蚁的繁殖结构由当地环境因子塑造，且不同物种对这些环境因子的响应存在差异。