Lamarre Vincent, Franke Alastair, Love Oliver P, Legagneux Pierre, Bêty Joël
Département de biologie, chimie et géographie et Centre d'études nordiques, Université du Québec à Rimouski, 300 allée des Ursulines, Rimouski, QC, G5L 3A1, Canada.
Arctic Raptors Project, Box 626, Rankin Inlet, NU, X0C 0G0, Canada.
Oecologia. 2017 Mar;183(3):653-666. doi: 10.1007/s00442-016-3797-9. Epub 2017 Jan 5.
For migratory species, acquisition and allocation of energy after arrival on the breeding grounds largely determine reproductive decisions. Few studies have investigated underlying physiological mechanisms driving variation in breeding phenology so far. We linked physiological state to individual timing of breeding in pre-laying arctic-nesting female peregrine falcons (Falco peregrinus tundrius). We captured females from two populations 2-20 days before egg-laying to assess plasma concentration of β-hydroxybutyric acid (BUTY) and triglyceride (TRIG), two metabolites known to reflect short-term changes in fasting and fattening rate, respectively. We also assessed baseline corticosterone (CORTb), a hormone that mediates energy allocation, and the scaled mass index (SMI) as an indicator of somatic body reserves. Plasma BUTY was slightly higher during the pre-recruiting period compared to the period of rapid follicular growth, indicating a reduction in catabolism of lipid reserves before investment in follicle development. Conversely, TRIG levels increased in pre-recruiting females, and best-predicted individual variation in pre-laying interval and lay date. A marked increase in CORTb occurred concomitantly with the onset of rapid follicle growth. SMI was highly variable possibly reflecting variation in food availability or individuals at different stages. Results suggest that (1) lower rates of pre-laying fattening and/or lower mobilization rate of lipoproteins to ovarian follicles delayed laying, and (2) an elevation in pre-laying CORTb may result from, or be required to compensate for, the energetic costs of egg production. Results of this study illustrate how variation in the allocation of energy before laying can influence individual fitness-related reproductive decisions.
对于迁徙物种而言，到达繁殖地后的能量获取与分配在很大程度上决定了繁殖决策。到目前为止，很少有研究探究驱动繁殖物候变化的潜在生理机制。我们将生理状态与北极筑巢的游隼（矛隼苔原亚种）雌鸟产卵前的个体繁殖时间联系起来。我们在产卵前2至20天从两个种群中捕获雌鸟，以评估β-羟基丁酸（BUTY）和甘油三酯（TRIG）的血浆浓度，这两种代谢物分别反映禁食和育肥率的短期变化。我们还评估了基础皮质酮（CORTb），一种介导能量分配的激素，以及作为躯体储备指标的体质量指数（SMI）。与卵泡快速生长时期相比，招募前期的血浆BUTY略高，这表明在投资卵泡发育之前，脂质储备的分解代谢有所减少。相反，招募前期雌鸟的TRIG水平升高，并且能最好地预测产卵前间隔和产卵日期的个体差异。随着卵泡快速生长的开始，CORTb显著增加。SMI变化很大，可能反映了食物可获得性的差异或处于不同阶段的个体差异。结果表明：（1）产卵前育肥率较低和/或脂蛋白向卵巢卵泡的动员率较低会延迟产卵；（2）产卵前CORTb升高可能是由产卵的能量消耗导致的，或者是为了补偿产卵的能量消耗。本研究结果说明了产卵前能量分配的变化如何影响与个体适应性相关的繁殖决策。
