Olsen K, Reynolds K T, Hoffmann A A
Centre for Environmental Stress and Adaptation Research, La Trobe University, Bundoora, Victoria 3083, Australia.
Heredity (Edinb). 2001 Jun;86(Pt 6):731-7. doi: 10.1046/j.1365-2540.2001.00892.x.
Wolbachia endosymbionts are known to affect the fitness of their hosts, but most of this information is from laboratory studies. In Drosophila melanogaster, Wolbachia frequencies vary clinically in frequency in Australia and may confound climatic adaptation. Here we use field cages in a reciprocal exchange design to test for Wolbachia effects in D. melanogaster in winter at temperate and tropical sites. Infected flies of both populations had a lower fecundity in tropical north Queensland, whilst in temperate southern Victoria Wolbachia effects depended on the nuclear population background. Here infected flies from Victoria were more fecund. Wolbachia also influenced larval/pupal viability in the tropics but this was dependent on population background. In comparisons of the populations, there was no evidence for local adaptation for total fecundity, viability or survival over winter. However, in Victoria, a local population had a higher late-life fecundity than a tropical population from Queensland that had higher early-life fecundity. At a tropical site, local Queensland flies had a higher early fecundity than Victorian flies. In contrast to many laboratory studies, mortality rates in the field cages increased only slightly over time. Both the Wolbachia effects and population differences have not been previously detected in laboratory studies with D. melanogaster and highlight the utility of Drosophila field studies in fitness experiments.
已知沃尔巴克氏体共生菌会影响其宿主的适合度，但大部分此类信息都来自实验室研究。在澳大利亚，黑腹果蝇体内的沃尔巴克氏体频率在临床上存在差异，这可能会混淆气候适应性。在此，我们采用双向交换设计的野外笼子，以测试在温带和热带地区冬季时沃尔巴克氏体对黑腹果蝇的影响。在昆士兰北部热带地区，两个种群的受感染果蝇繁殖力都较低，而在维多利亚州南部温带地区，沃尔巴克氏体的影响则取决于核种群背景。在此，来自维多利亚州的受感染果蝇繁殖力更强。沃尔巴克氏体还影响了热带地区幼虫/蛹的存活力，但这取决于种群背景。在对这些种群的比较中，没有证据表明在总繁殖力、存活力或越冬存活率方面存在局部适应性。然而，在维多利亚州，一个本地种群的晚年繁殖力高于来自昆士兰的热带种群，后者具有较高的早期繁殖力。在一个热带地点，昆士兰本地果蝇的早期繁殖力高于维多利亚州果蝇。与许多实验室研究不同的是，野外笼子中的死亡率随时间仅略有增加。沃尔巴克氏体的影响和种群差异在之前的黑腹果蝇实验室研究中均未被发现，这凸显了果蝇野外研究在适合度实验中的实用性。
