Primate Behavioral Ecology Lab, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Mexico.
Posgrado en Neuroetología, Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Mexico.
Am J Phys Anthropol. 2021 Mar;174(3):396-406. doi: 10.1002/ajpa.24222. Epub 2021 Jan 11.
Reproduction entails several challenges to primate females, among which energetic costs are remarkable at certain stages of the reproductive cycle. Still, females may use behavioral and physiological strategies to cope with those challenges. We had previously reported covariation between female energetic condition through the reproductive cycle and time-budget adjustments in mantled howler monkeys (Alouatta palliata). Accordingly, we suggested that behavioral flexibility allowed coping with the energetic challenges of reproduction. Subsequent evidence from the same population, however, suggested otherwise, so we performed a follow-up study on the variation in female reproductive energetics based on a larger sample of females.
We studied 48 free-ranging adult females at Los Tuxtlas (Mexico). We assessed energy balance via urinary C-peptide concentrations (2717 urine samples), behavioral energy intake and expenditure (5728 sampling hours), and physiological energy expenditure via fecal triiodothyronine metabolites (fTH3; 3138 fecal samples).
We found that energy balance varied among reproductive states: (a) cycling was a period of low C-peptide concentrations; (b) the highest C-peptide concentrations occurred during gestation; and (c) the beginning of lactation marked a notable decrease in C-peptide concentrations, which then improved at mid-lactation to again decline at lactation offset. These peaks and valleys in energy balance did not seem to be associated with variation in energy acquisition but were rather mirrored by activity levels and fTH3 during lactation.
Energy balance was not preserved through the reproductive cycle, supporting previous contentions that the reproductive performance of female mantled howler monkeys may be energetically constrained. The contrast between these and results that we have previously reported, highlights the importance of conducting follow-up studies to continually improve our understanding of the reproductive energetics of primate females.
生殖对灵长类雌性动物来说存在诸多挑战，其中在生殖周期的某些阶段，能量消耗非常显著。然而，雌性动物可能会采用行为和生理策略来应对这些挑战。我们之前曾报道过，在绒猴（Alouatta palliata）中，雌性动物在生殖周期中的能量状况与时间预算调整之间存在相关性。因此，我们认为行为灵活性使它们能够应对生殖过程中的能量挑战。然而，来自同一研究群体的后续证据表明并非如此，因此我们对更大样本量的雌性个体的生殖能量变化进行了后续研究。
我们在 Los Tuxtlas（墨西哥）对 48 只自由放养的成年雌性个体进行了研究。我们通过尿 C-肽浓度（2717 个尿液样本）、行为能量摄入和支出（5728 个采样小时）以及粪便三碘甲状腺原氨酸代谢物（fTH3；3138 个粪便样本）评估能量平衡。
我们发现能量平衡在生殖状态之间存在差异：（a）发情周期是 C-肽浓度较低的时期；（b）妊娠期间 C-肽浓度最高；（c）哺乳期开始时 C-肽浓度显著下降，然后在哺乳期中期有所改善，再次下降到哺乳期结束时。这些能量平衡的峰值和低谷似乎与能量获取的变化无关，而是与哺乳期的活动水平和 fTH3 相吻合。
能量平衡在生殖周期中并未得到维持，这支持了之前的观点，即雌性绒猴的生殖表现可能受到能量限制。这些结果与我们之前报告的结果形成对比，突出了进行后续研究以不断提高我们对灵长类雌性生殖能量学的理解的重要性。
