Vishalakshi C, Singh B N
Genetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, India.
Genome. 2006 Jul;49(7):777-85. doi: 10.1139/g06-031.
Fluctuating asymmetry (FA, subtle random deviations from perfect bilateral symmetry) is often used as a measure of developmental instability (DI), which results from perturbations in developmental pathways caused by genetic or environmental stressors. During the present study, we estimated FA in 5 morphological traits, viz. wing length (WL), wing to thorax ratio (W:T), sternopleural bristle number (SBN), sex-comb tooth number (SCTN), and ovariole number (ON) in 18 laboratory populations of Drosophila ananassae. FA levels of measured traits differed significantly among populations except for SBN (in males and females) and W:T ratio (in females). Positional fluctuating asymmetry (PFA), a sensitive measure of DI, also varied significantly among the populations for SBN in females and SCTN in males. Interestingly, both males and females were similar for nonsexual traits. However, when FA across all traits (sexual and nonsexual) was combined into a single composite index (CFA), significant differences were found for both populations and sexes. Males showed higher CFA values than females, suggesting that males are more prone to developmental perturbations. The magnitude of FA differed significantly among traits, being lowest for nonsexual traits (SBN, WL, W:T ratio) and highest for sexual traits (SCTN and ON). The trait size of sexual traits (SCTN and ON) was positively correlated with their asymmetry. The possible reasons for variation in FA both among traits and among populations, and the usefulness of FA as an indicator of developmental stress and phenotypic quality in D. ananassae are discussed.
波动不对称性（FA，即与完美双侧对称的细微随机偏差）常被用作发育不稳定性（DI）的一种度量，发育不稳定性是由遗传或环境应激源导致的发育途径扰动所引起的。在本研究中，我们估计了18个拟果蝇实验室种群中5种形态特征的波动不对称性，即翅长（WL）、翅与胸比例（W:T）、腹侧板刚毛数（SBN）、性梳齿数（SCTN）和卵巢管数（ON）。除SBN（雄性和雌性）和W:T比例（雌性）外，各测量特征的波动不对称性水平在不同种群间存在显著差异。位置波动不对称性（PFA）是发育不稳定性的一种敏感度量，对于雌性的SBN和雄性的SCTN，其在不同种群间也存在显著差异。有趣的是，对于非性特征，雄性和雌性表现相似。然而，当将所有特征（性特征和非性特征）的波动不对称性合并为一个单一的综合指数（CFA）时，发现种群和性别之间均存在显著差异。雄性的CFA值高于雌性，这表明雄性更容易受到发育扰动。波动不对称性的程度在不同特征间存在显著差异，非性特征（SBN、WL、W:T比例）的波动不对称性最低，性特征（SCTN和ON）的波动不对称性最高。性特征（SCTN和ON）的特征大小与其不对称性呈正相关。本文讨论了波动不对称性在特征间和种群间变化的可能原因，以及波动不对称性作为拟果蝇发育应激和表型质量指标的有用性。
