Hybrid Fitness in a Locally Adapted Parasite
Hybrid Fitness in a Locally Adapted Parasite
复制标题
DOI：
10.1086/592866
复制
发表时间：
2008-12-01
影响因子：
2.9
通讯作者：
Lively, Curtis M.
中科院分区：
文献类型：
--
作者：
Dybdahl, Mark F.;Jokela, Jukka;Lively, Curtis M.
维持有性繁殖和遗传多样性的寄生虫(红皇后)假说假定宿主-寄生虫的相互作用是紧密的遗传专一性的结果。因此，只要基因效应是非加性的，不同寄生虫种群之间的杂交将有望扰乱适应性基因组合，导致接触亲本共生宿主的传染性降低。相反，杂交不会降低异地宿主的传染性，除非不同的寄生虫种群拥有当它们结合时本质上不相容的等位基因。在三个不同的实验中，我们比较了当地适应的寄生虫(吸虫)种群和F1杂交寄生虫在接触与这两种寄生虫种群中的一种共面的宿主(蜗牛)种群时的传染性。我们在两个实验中测试了内在的遗传不亲和性，包括一个与两个寄生虫种群都是异源的寄主种群。正如预测的那样，当目标寄主种群与寄生种群同域时，杂交种的侵染率显著低于亲本平均水平，而异地寄主上的杂交种寄生虫则不是，从而排除了内在的遗传不亲和性。这一结果与共同进化理论和红皇后假说所设想的寄生虫分化背后的非加性基因效应和紧密特定的宿主驱动的选择是一致的。
The parasite (Red Queen) hypothesis for the maintenance of sexual reproduction and genetic diversity assumes that host-parasite interactions result from tight genetic specificity. Hence, hybridization between divergent parasite populations would be expected to disrupt adaptive gene combinations, leading to reduced infectivity on exposure to parental sympatric hosts, as long as gene effects are nonadditive. In contrast, hybridization would not cause reduced infectivity on allopatric hosts unless the divergent parasite populations possess alleles that are intrinsically incompatible when they are combined. In three different experiments, we compared the infectivity of locally adapted parasite (trematode) populations with that of F 1 hybrid parasites when exposed to host (snail) populations that were sympatric to one of the two parasite populations. We tested for intrinsic genetic incompatibilities in two experiments by including one host population that was allopatric to both parasite populations. As predicted, when the target host populations were sympatric to the parasite populations, the hybrids were significantly less infective than the parental average, while hybrid parasites on allopatric hosts were not, thereby ruling out intrinsic genetic incompatibilities. The results are consistent with nonadditive gene effects and tightly specific host-driven selection underlying parasite divergence, as envisioned by coevolutionary theory and the Red Queen hypothesis.