EXPRESSION OF GENETIC VARIATION IN BODY SIZE OF THE COLLARED FLYCATCHER UNDER DIFFERENT ENVIRONMENTAL CONDITIONS
EXPRESSION OF GENETIC VARIATION IN BODY SIZE OF THE COLLARED FLYCATCHER UNDER DIFFERENT ENVIRONMENTAL CONDITIONS
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DOI：
10.1111/j.1558-5646.1997.tb02440.x
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发表时间：
1997-04
期刊：
影响因子：
3.3
通讯作者：
J. Merilä
中科院分区：
文献类型：
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作者：
J. Merilä
在两个实验创造的环境中，分别代表良好和不良的饲养条件，身体大小的遗传力，估计使用交叉培养的领蝇Ficedula albicollis雏鸟。在不良饲养条件下饲养的幼仔比在良好饲养条件下饲养的全同胞仔获得更小的体型（跗骨长度）。亲子回归分析显示，在不良饲养条件下，体型的遗传力（h2）低于良好饲养条件下。因此，由于在两种环境中使用相同的亲本组来估计h2，这表明加性遗传方差分量（VA）的环境依赖性变化，或者亲本与不良后代环境之间的遗传相关性小于亲本与良好后代环境之间的遗传相关性。然而，全同胞分析未能找到基因型-环境相互作用的证据，尽管这些检验的功效可能很低。两种环境中的全同胞遗传力往往高于亲子回归的估计值，表明孵化前或孵化后早期的共同环境/母体效应可能会夸大VA的全同胞估计值。同胞竞争对VA估计值的影响可能很小，因为孵化后第2天的雏鸟大小等级通常与雏鸟的大小等级不相关。此外，在孵化期间母体的身体状况和后代的最终大小之间没有相关性，表明与营养状况有关的直接母体影响很小。对早期鸟类体型变异的定量遗传研究的回顾表明，在9个案例中，有8个案例的体型遗传力在恶劣的环境条件下低于良好的环境条件。这种关系的主要含义是在恶劣的环境条件下，对选择的进化反应会降低。另一方面，这将通过降低选择的准确性来减缓遗传变异的损失，并可能有助于解释在良好的环境条件下体型性状的中度到高度遗传性。
Heritability of body size in two experimentally created environments, representing good and poor feeding conditions, respectively, was estimated using cross‐fostered collared flycatcher Ficedula albicollis nestlings. Young raised under poor feeding conditions attained smaller body size (tarsus length) than their full‐sibs raised under good feeding conditions. Parent‐offspring regressions revealed lower heritability (h2) of body size under poor than under good feeding conditions. Hence, as the same set of parents were used in the estimation of h2 in both environments, this suggests environment‐dependent change in additive genetic component of variance (VA), or that the genetic correlation between parental and poor offspring environment was less than that between parental and good offspring environment. However, full‐sib analyses failed to find evidence for genotype‐environment interactions, although the power of these tests might have been low. Full‐sib heritabilities in both environments tended to be higher than estimates from parent‐offspring regressions, indicating that prehatching or early posthatching common environment/maternal effects might have inflated full‐sib estimates of VA. The effect of sibling competition on estimates of VA was probably small as the nestling size‐hierarchy at day 2 posthatch was not generally correlated with size‐hierarchy at fledging. Furthermore, there was no correlation between maternal body condition during the incubation and final size of offspring, indicating that direct maternal effects related to nutritional status were small. A review of earlier quantitative genetic studies of body size variation in birds revealed that in eight of nine cases, heritability of body size was lower in poor than in good environmental conditions. The main implication of this relationship will be a decreased evolutionary response to selection under poor environmental conditions. On the other hand, this will retard the loss of genetic variation by reducing the accuracy of selection and might help explain the moderate to high heritabilities of body‐size traits under good environmental conditions.