Gebhardt-Henrich S G
Zoologisches Institut, Basel, Switzerland.
Growth Dev Aging. 1992 Spring;56(1):23-33.
Simulations of nestling growth in Great Tits (Parus major) were used to show the consequences genetic variation in the parameters of growth curves could have on the amount of genetic variation in final body weight. This was done for the case of good environmental conditions (i.e. adequate food supply), and for poor environmental conditions (food limitation). A three-parameter process-error growth model based on the Richards curve (Brisbin et al., 1986) was used. The three parameters were the asymptote, the shape, and the time to complete approximately 95% of growth. In simulations, where only the asymptotic value was heritable, genetic variation in final weight was larger under good conditions than under poor conditions. Food limitations decreased the amount of genetic variation and the heritability estimate of final size. Similarly, sib competition, (based on body size differences of nestlings within broods) combined with food limitations lowered heritabilities. Sib competition under good conditions had no effect on heritabilities. In contrast, when the time to complete approximately 95% of growth was heritable, heritabilities for final size were not lower under poor conditions either without or in the presence of sib competition. This model suggests that different amounts of genetic variation in final size under good and poor conditions could be linked to the amount of genetic variation present in the growth curve parameters. The results agreed with an empirical study on body weight in a passerine bird, the Great Tit, where only the asymptote displayed heritable variation and more genetic variance was expressed under good conditions.
对大山雀（Parus major）雏鸟生长的模拟被用于展示生长曲线参数的遗传变异对最终体重遗传变异量可能产生的影响。这是在良好环境条件（即充足的食物供应）和恶劣环境条件（食物受限）两种情况下进行的。使用了基于理查兹曲线的三参数过程误差生长模型（Brisbin等人，1986年）。这三个参数分别是渐近线、形状以及完成约95%生长所需的时间。在模拟中，当只有渐近值是可遗传的时，良好条件下最终体重的遗传变异比恶劣条件下更大。食物限制减少了遗传变异量以及最终体型的遗传力估计值。同样，同胞竞争（基于一窝雏鸟内的体型差异）与食物限制相结合会降低遗传力。良好条件下的同胞竞争对遗传力没有影响。相比之下，当完成约95%生长所需的时间是可遗传的时，无论有无同胞竞争，恶劣条件下最终体型的遗传力都不会更低。该模型表明，良好和恶劣条件下最终体型遗传变异量的差异可能与生长曲线参数中存在的遗传变异量有关。结果与对一种雀形目鸟类大山雀体重的实证研究一致，在该研究中只有渐近线表现出可遗传变异，并且在良好条件下表达出更多的遗传方差。
