Leary Robb F, Allendorf Fred W, Knudsen Kathy L
Department of Zoology, University of Montana, Missoula, MT, 59812.
Evolution. 1985 Nov;39(6):1318-1326. doi: 10.1111/j.1558-5646.1985.tb05697.x.
Interspecific hybrids have been proposed to have reduced developmental stability in comparison to their parental species because the parental genomes have not undergone selection for the maintenance of developmental stability when they occur together. We present data from four interspecific hybrids of salmonid fishes that support this view. Natural hybrids of bull trout (Salvelinus confluentus) with brook trout (Salvelinus fontinalis) and laboratory hybrids of rainbow trout (Salmo gairdneri) with Yellowstone (Salmo clarki bouvieri), westslope (S. c. lewisi), and coastal (S. c. clarki) cutthroat trout all have higher levels of fluctuating asymmetry than either of their parental species raised in the same environment. Thus, the hybrids have reduced developmental stability. The hybrids do not have meristic counts intermediate to the counts of the parental species. The hybrids usually have counts as high as the species with the higher count for those characters that differ between the parental species and often have higher counts for those characters that do not differ between the parental species. We suggest that the tendency for interspecific hybrids to have high meristic counts may be related to differences between the species in the length and timing of the developmental periods during which the counts of the characters are determined.
与亲本物种相比，种间杂种被认为发育稳定性降低，因为当亲本基因组同时出现时，它们没有经历维持发育稳定性的选择。我们提供了来自四种鲑科鱼类种间杂种的数据来支持这一观点。公牛鳟（Salvelinus confluentus）与溪鳟（Salvelinus fontinalis）的自然杂种以及虹鳟（Salmo gairdneri）与黄石（Salmo clarki bouvieri）、西坡（S. c. lewisi）和沿海（S. c. clarki）割喉鳟的实验室杂种，在相同环境下饲养时，其波动不对称水平均高于任何一个亲本物种。因此，杂种的发育稳定性降低。杂种的可数性状计数并非介于亲本物种计数之间。对于亲本物种之间不同的那些性状，杂种的计数通常与计数较高的物种一样高，而对于亲本物种之间没有差异的那些性状，杂种的计数往往更高。我们认为，种间杂种可数性状计数高的趋势可能与物种在确定性状计数的发育时期的长度和时间方面的差异有关。
