Beekman M, Allsopp M H, Wossler T C, Oldroyd B P
Behaviour and Genetics of Social Insects Lab, School of Biological Sciences A12, University of Sydney, Sydney, Australia.
Heredity (Edinb). 2008 Jan;100(1):13-8. doi: 10.1038/sj.hdy.6801058. Epub 2007 Sep 12.
Hybrid zones are found wherever two populations distinguishable on the basis of heritable characters overlap spatially and temporally and hybridization occurs. If hybrids have lower fitness than the parental types a tension zone may emerge, in which there is a barrier to gene flow between the two parental populations. Here we discuss a hybrid zone between two honeybee subspecies, Apis mellifera capensis and A. m. scutellata and argue that this zone is an example of a tension zone. This tension zone is particularly interesting because A. m. capensis can be a lethal social parasite of A. m. scutellata. However, despite its parasitic potential, A. m. capensis appears to be unable to increase its natural range unassisted. We propose three interlinked mechanisms that could maintain the South African honeybee hybrid zone: (1) low fitness of intercrossed and genetically mixed colonies arising from inadequate regulation of worker reproduction; (2) higher reproductive success of A. m. scutellata via both high dispersal rates into the hybrid zone and increased competitiveness of males, countered by (3) the parasitic nature of A. m. capensis.
只要两个基于可遗传特征可区分的种群在空间和时间上重叠并发生杂交，就会出现杂交带。如果杂种的适应性低于亲本类型，可能会出现一个紧张带，在这个区域中两个亲本种群之间存在基因流动的障碍。在这里，我们讨论两个蜜蜂亚种海角蜜蜂（Apis mellifera capensis）和东非蜜蜂（A. m. scutellata）之间的杂交带，并认为这个区域是一个紧张带的例子。这个紧张带特别有趣，因为海角蜜蜂可能是东非蜜蜂的一种致命社会性寄生虫。然而，尽管海角蜜蜂具有寄生潜力，但它似乎无法在没有帮助的情况下扩大其自然分布范围。我们提出了三种相互关联的机制，这些机制可能维持南非蜜蜂杂交带：（1）由于工蜂繁殖调控不足，杂交和基因混合群体的适应性较低；（2）东非蜜蜂通过高扩散率进入杂交带和雄性竞争力的提高而具有较高的繁殖成功率，与之相对的是（3）海角蜜蜂的寄生特性。
