Holloway Graham J, de Jong Peter W, Ottenheim Mart
Department of Pure and Applied Zoology, AMS Building, University of Reading, Whiteknights, P.O. Box 228 Reading, Berkshire, RG6 2AJ, United Kingdom.
Section of Evolutionary Biology, Department of Population Biology, University of Leiden, Schelpenkade 14a, 2313 ZT Leiden, The Netherlands.
Evolution. 1993 Aug;47(4):1229-1239. doi: 10.1111/j.1558-5646.1993.tb02149.x.
Ladybirds (Coccinellidae) defend themselves against attack by vertebrate predators by exuding a fluid from the femero-tibial joints. This fluid carries a noxious or toxic alkaloid. The amount of fluid produced during a single attack can be very high (up to 20% of fresh body weight), and the weight of the self-synthesized alkaloid can amount to several percent of the weight of the fluid. A study was carried out on these two defense characters and two other fitness characters (body weight and growth rate) to demonstrate a cost to defense in the form of genetic trade-offs between characters. The two sexes were analyzed separately, and a jackknife procedure was used to attach errors to the estimates of V and cov . All four characters were associated with high levels of V , but the cov values were mixed, some being negative and others positive. Principal-component analysis indicated the operation of factors constraining the cov values in males, and further possible reasons for the appearance of so many positive values are explored. A matrix analysis showed that the genetic variance/covariance matrices of the two sexes were significantly different from each other. Breeding values derived from sons plotted on breeding values from daughters had correlation coefficients significantly less than +1. This finding indicated that a substantial amount of sex-dependent gene expression was occurring.
瓢虫（瓢虫科）通过从股胫关节分泌一种液体来抵御脊椎动物捕食者的攻击。这种液体含有一种有毒或有害的生物碱。单次攻击中产生的液体量可能非常高（高达新鲜体重的20%），且自身合成的生物碱重量可达液体重量的百分之几。针对这两种防御特征以及另外两个适合度特征（体重和生长速率）进行了一项研究，以证明防御是以特征之间的遗传权衡形式存在成本的。对两性分别进行了分析，并使用刀切法将误差附加到V和协方差的估计值上。所有四个特征都与高水平的V相关，但协方差值各异，有些为负，有些为正。主成分分析表明存在限制雄性协方差值的因素在起作用，并探讨了出现如此多正值的进一步可能原因。矩阵分析表明两性的遗传方差/协方差矩阵彼此显著不同。儿子的育种值与女儿的育种值绘制在一起，相关系数显著小于 +1。这一发现表明发生了大量的性别依赖性基因表达。
