Section of Ecology, Department of Biology, University of Turku, Turku, Finland.
PLoS One. 2011;6(11):e25360. doi: 10.1371/journal.pone.0025360. Epub 2011 Nov 14.
Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk androgens and yolk total carotenoids. We found significant variation among populations in most egg components, but ca. 90% of the variation was among individuals within populations. Population however explained 40% of the variation in carotenoid levels. In contrast to our hypothesis, we found geographical trends only in carotenoids, but not in any of the other egg components. Our results thus suggest high within-population variation and leave little scope for local adaptation and genetic differentiation in deposition of different egg components. The role of these maternally-derived resources in evolutionary change should be further investigated.
在许多动植物类群中，生殖、表型和生活史特征表现出地理变异，表明选择机制存在空间变异。亲代向鸟类卵中沉积的物质，如激素、抗体和抗氧化剂，对后代的发育有至关重要的影响，并对表型和适应性产生持久的影响。然而，关于亲代向卵中沉积物质的大规模地理变异模式，我们知之甚少。我们通过从 16 个种群中收集样本，并测量卵和蛋黄的质量、白蛋白溶菌酶活性、蛋黄免疫球蛋白、蛋黄雄激素和蛋黄总类胡萝卜素，研究了雀形目鸟类-白腰文鸟（Ficedula hypoleuca）卵成分的地理变异。我们发现，大多数卵成分在种群间存在显著差异，但种群内个体间的差异约为 90%。然而，种群解释了类胡萝卜素水平变异的 40%。与我们的假设相反，我们只发现了地理趋势在类胡萝卜素中，而在其他任何卵成分中都没有发现。因此，我们的研究结果表明，种群内的变异较高，而在不同卵成分的沉积中，几乎没有适应和遗传分化的余地。这些由母体衍生而来的资源在进化变化中的作用应进一步研究。
