Hörnfeldt B, Hipkiss T, Fridolfsson A K, Eklund U, Ellegren H
Department of Ecology & Environmental Science, Umeå University, SE-901 87 Umeå, Sweden.
Mol Ecol. 2000 Feb;9(2):187-92. doi: 10.1046/j.1365-294x.2000.00847.x.
A nest box population of Tengmalm's owls (Aegolius funereus) in northern Sweden was studied to investigate the effects of extra food on the sex ratio between hatching and fledging in this sexually size-dimorphic species. The brood size and brood sex ratio of supplementary-fed and control broods were compared. Newly hatched nestlings were blood sampled and sexed by polymerase chain reaction (PCR) amplification of the sex-linked CHD1Z and CHD1W genes. The brood sex ratio at hatching was strongly male biased (65%); this was also the case in broods where all eggs hatched (72%). There was no relationship between hatch order and sex ratio, and hatching sex ratio did not vary significantly with laying date. Brood size decreased between hatching and fledging, but did not differ between fed and control broods at either stage. Brood sex ratio did not differ between hatching and fledging, and fledging sex ratio did not differ between fed and control broods. It was concluded that, at least during the year in which the study was carried out, feeding had no effect on brood reduction, and that male and female nestlings did not show any differential mortality. The mechanisms behind the male-biased sex ratio at hatching, and any possible adaptive reasons for it, are not known.
对瑞典北部一个长耳鸮（Aegolius funereus）巢箱种群进行了研究，以调查额外食物对这种两性体型存在差异的物种在孵化和出飞之间的性别比例的影响。比较了补充喂食巢和对照巢的窝雏数和窝雏性别比例。对新孵化的雏鸟进行采血，并通过对性连锁CHD1Z和CHD1W基因进行聚合酶链反应（PCR）扩增来确定性别。孵化时的窝雏性别比例严重偏向雄性（65%）；所有卵都孵化的窝雏也是这种情况（72%）。孵化顺序与性别比例之间没有关系，孵化性别比例也不会随产卵日期有显著变化。窝雏数在孵化和出飞之间减少，但在这两个阶段，喂食组和对照组的窝雏数没有差异。孵化和出飞时窝雏性别比例没有差异，出飞时的性别比例在喂食组和对照组之间也没有差异。得出的结论是，至少在进行研究的这一年里，喂食对窝雏减少没有影响，雄性和雌性雏鸟没有表现出任何差异死亡率。孵化时雄性偏向的性别比例背后的机制以及任何可能的适应性原因尚不清楚。
