Leamy L J, Meagher S, Taylor S, Carroll L, Potts W K
Department of Biology, University of North Carolina at Charlotte, 28223, USA.
Evolution. 2001 Nov 11;55(11):2333-41. doi: 10.1111/j.0014-3820.2001.tb00746.x.
Fluctuating asymmetry (FA), a ubiquitous type of asymmetry of bilateral characters, often has been used as a measure of developmental instability in populations. FA is expected to increase in populations subjected to genetic stressors such as inbreeding or environmental stressors such as toxins or parasites, although results have not always been consistent. We tested whether FA in four skeletal size characters and mandible shape was greater in a population of wild-derived mice reared in the laboratory and subjected to one generation of inbreeding (F = 0.25) versus that in an outbred group (F = 0.00). FA did not significantly differ between the inbred and outbred groups, despite the fact that these two groups differed dramatically in fitness under seminatural population conditions. As far as we know, this is the first study to evaluate the relationship between FA and inbreeding in wild house mice, and our general conclusion is opposite that of earlier work on laboratory inbred strains of mice and their hybrids. Size for two of the characters was significantly less in inbreds than in outbreds, however, and there was a significant difference between inbreds and outbreds in the signed differences of right and left sides in one character (humerus length). Some of the mice in both groups also were heterozygous or homozygous carriers of the t-complex. Because mice carrying this chromosome 17 variant are known to have reduced fitness, we also tested whether they had greater FA than mice carrying non-t-haplotypes. The overall level of a composite FA index calculated from all four characters was in fact significantly higher in the t-bearing mice. These combined results suggest that FA is not a generally sensitive proxy measure for fitness, but can be associated with fitness reductions for certain genetic stressors.
波动不对称性（FA）是双侧性状中普遍存在的一种不对称类型，常被用作衡量种群发育稳定性的指标。预计在受到遗传应激源（如近亲繁殖）或环境应激源（如毒素或寄生虫）影响的种群中，FA会增加，尽管结果并不总是一致。我们测试了在实验室饲养并经历一代近亲繁殖（F = 0.25）的野生来源小鼠群体中，四个骨骼大小性状和下颌形状的FA是否比远交群体（F = 0.00）更大。尽管这两组在半自然种群条件下的适应性差异巨大，但近亲繁殖组和远交组之间的FA没有显著差异。据我们所知，这是第一项评估野生家鼠中FA与近亲繁殖关系的研究，我们的总体结论与早期关于实验室近交系小鼠及其杂种的研究相反。然而，其中两个性状的大小在近亲繁殖小鼠中明显小于远交小鼠，并且在一个性状（肱骨长度）的左右两侧的符号差异上，近亲繁殖小鼠和远交小鼠之间存在显著差异。两组中的一些小鼠也是t-复合体的杂合子或纯合子携带者。由于已知携带这种17号染色体变体的小鼠适应性降低，我们还测试了它们的FA是否比携带非t单倍型的小鼠更大。事实上，从所有四个性状计算出的综合FA指数的总体水平在携带t的小鼠中显著更高。这些综合结果表明，FA并非普遍适用于衡量适应性的敏感指标，但对于某些遗传应激源，FA可能与适应性降低有关。
