Department of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G 2W1.
1063 Oxtongue Lake Road, Dwight, ON, Canada P0A 1H0.
Proc Biol Sci. 2023 Apr 26;290(1997):20221863. doi: 10.1098/rspb.2022.1863. Epub 2023 Apr 19.
While delaying natal dispersal can provide short-term benefits for juveniles, lifetime fitness consequences are rarely assessed. Furthermore, competition for limited positions on a natal territory could impose an indirect fitness cost on the winner if the outcome has negative effects on its siblings. We use radio-tracking and 58 years of nesting data in Ontario, Canada to examine the lifetime fitness consequences of sibling expulsion in the Canada jay (). Six weeks after fledging, intra-brood dominance struggles result in one 'dominant juvenile' (DJ) remaining on the natal territory after expelling its subordinate siblings, the 'ejectees' (EJs). Despite an older age-at-first-reproduction, DJs produced more recruits over their lifetime and had higher first-year survival than EJs, leading to substantially higher direct fitness. Even though DJs incurred an indirect fitness cost by expelling their siblings and there was no evidence that their presence on the natal territory increased their parents' reproductive output the following year, they still had substantially higher inclusive fitness than EJs. Our results demonstrate how early-life sibling conflict can have lifetime consequences and that such fitness differences in Canada jays are driven by the enhanced first-year survival of DJs pursuant to the early-summer expulsion of their sibling competitors.
虽然延迟自然扩散可以为幼鸟提供短期利益，但很少评估其对终生适应度的影响。此外，如果获胜者的结果对其兄弟姐妹产生负面影响，那么在其出生地争夺有限的位置可能会给获胜者带来间接的适应度成本。我们使用加拿大安大略省的无线电跟踪和 58 年的筑巢数据，研究了在加拿大松鸦（）中驱逐兄弟姐妹对终生适应度的影响。在离巢后六周，由于内部的兄弟间的支配斗争，一只“优势幼鸟”（DJ）在驱逐其从属的兄弟姐妹“被驱逐者”（EJ）后留在出生地。尽管 DJ 的首次繁殖年龄较大，但它们在一生中繁殖的雏鸟更多，并且第一年的存活率高于 EJ，从而导致其直接适应度大大提高。尽管 DJ 通过驱逐其兄弟姐妹而遭受了间接适应度成本，并且没有证据表明它们在出生地的存在会增加其父母次年的繁殖输出，但它们的综合适应度仍然大大高于 EJ。我们的研究结果表明，早期的兄弟姐妹冲突如何对终生适应度产生影响，以及加拿大松鸦中的这种适应度差异是由 DJ 提前在夏初驱逐其竞争的兄弟姐妹从而提高第一年的存活率来驱动的。
