Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland.
BMC Ecol. 2012 Aug 18;12:17. doi: 10.1186/1472-6785-12-17.
Evidence is accumulating that telomere length is a good predictor of life expectancy, especially early in life, thus calling for determining the factors that affect telomere length at this stage. Here, we investigated the relative influence of early growth conditions and origin (genetics and early maternal effects) on telomere length of collared flycatchers (Ficedula albicollis) at fledging. We experimentally transferred hatchlings among brood triplets to create reduced, control (i.e. unchanged final nestling number) and enlarged broods.
Although our treatment significantly affected body mass at fledging, we found no evidence that increased sibling competition affected nestling tarsus length and telomere length. However, mixed models showed that brood triplets explained a significant part of the variance in body mass (18%) and telomere length (19%), but not tarsus length (13%), emphasizing that unmanipulated early environmental factors influenced telomere length. These models also revealed low, but significant, heritability of telomere length (h(2) = 0.09). For comparison, the heritability of nestling body mass and tarsus length was 0.36 and 0.39, respectively, which was in the range of previously published estimates for those two traits in this species.
Those findings in a wild bird population demonstrate that telomere length at the end of the growth period is weakly, but significantly, determined by genetic and/or maternal factors taking place before hatching. However, we found no evidence that the brood size manipulation experiment, and by extension the early growth conditions, influenced nestling telomere length. The weak heritability of telomere length suggests a close association with fitness in natural populations.
越来越多的证据表明，端粒长度是预测预期寿命的一个很好的指标，尤其是在生命早期，因此需要确定在这个阶段影响端粒长度的因素。在这里，我们研究了早期生长条件和起源（遗传和早期母体效应）对刚离巢的领雀嘴鹎（Ficedula albicollis）端粒长度的相对影响。我们通过在三胞胎巢中转移雏鸟来人为地创建减少、控制（即最终巢雏数量不变）和增大的巢。
尽管我们的处理显著影响了离巢时的体重，但我们没有证据表明增加的同胞竞争会影响雏鸟跗跖长度和端粒长度。然而，混合模型表明，巢三胞胎解释了体重（18%）和端粒长度（19%）的显著部分变异，但不是跗跖长度（13%），这强调了未受干预的早期环境因素会影响端粒长度。这些模型还显示出端粒长度的低但显著的遗传力（h²=0.09）。相比之下，雏鸟体重和跗跖长度的遗传力分别为 0.36 和 0.39，这在该物种这两个性状的先前发表的估计值范围内。
在野生鸟类种群中的这些发现表明，生长期末的端粒长度弱但显著地由孵化前的遗传和/或母体因素决定。然而，我们没有发现巢大小操纵实验的证据，更广泛地说，早期生长条件，影响了雏鸟的端粒长度。端粒长度的低遗传力表明其与自然种群中的适应性密切相关。
