Laboratoire d'Ethologie Expérimentale et Comparée UR 4443 (LEEC), Université Sorbonne Paris Nord, 93430, Villetaneuse, France.
Heimat-Tierpark Olderdissen (Bielefeld Zoo), Dornberger Straße 149a, 33619, Bielefeld, Germany.
Oecologia. 2023 Dec;203(3-4):435-451. doi: 10.1007/s00442-023-05477-9. Epub 2023 Nov 16.
Reproduction in young females can show a particularly sensitive response to environmental challenges, although empirical support from individual-based long-term studies is scarce. Based on a 20-year data set from a free-roaming Przewalski's horse population (Equus ferus przewalskii), we studied effects of large-herbivore density (horses + cattle) and weather conditions experienced during different life stages on females' annual birth rates. Foaling probability was very low in 2-year-olds, reaching maximum values in 5 to 10-year-olds, followed by a decrease in older females indicating reproductive senescence. Mother's previous reproductive investment affected her current reproduction; young and old mothers (as opposed to middle-aged ones), which had nursed a foal for at least 60 days during the previous year, reproduced with a lower probability. Foaling probability and body condition of young females were lower when large-herbivore density was high. Reproduction was also influenced by interactive weather effects during different life stages. Low late-summer precipitation during the females' year of birth was associated with a pronounced decrease in foaling probability in response to harsh late-winter temperatures prior to the mating season. In turn, increased amounts of late-summer rain during this early age together with more late-summer rain during the females' current pregnancy led to an increased reproductive probability in 2-3-year-olds. These results were corroborated by the ameliorating effects of late-summer rain on body condition in such females. In conclusion, our findings highlight the interactive importance of weather conditions experienced during early life, and of density and weather during current pregnancy on foaling probability, particularly in young females.
年轻雌性的繁殖能力对环境挑战表现出特别敏感的反应，尽管缺乏基于个体的长期研究的经验支持。基于一个 20 年的自由放养普氏野马种群（Equus ferus przewalskii）的数据，我们研究了大型食草动物密度（马+牛）和不同生命阶段经历的天气条件对雌性年度出生率的影响。2 岁的母马产驹的可能性非常低，5 到 10 岁的母马达到最大值，然后老年母马的产驹率下降，表明生殖衰老。母亲以前的繁殖投资会影响她当前的繁殖；年轻和年老的母亲（与中年母亲相反），如果在前一年至少哺乳了 60 天的小马驹，那么繁殖的可能性就会降低。当大型食草动物密度较高时，年轻母马的产驹概率和身体状况较低。繁殖也受到不同生命阶段的交互天气效应的影响。母马出生当年夏末降水较少与交配季节前冬季后期恶劣温度导致产驹概率显著下降有关。反过来，在这个早期年龄，夏末降雨增加，以及母马当前怀孕期的夏末降雨增加，导致 2-3 岁的母马繁殖概率增加。夏末降雨对这些母马身体状况的改善作用证实了这些结果。总之，我们的研究结果强调了早期生活中经历的天气条件以及当前怀孕期的密度和天气对产驹概率的交互重要性，特别是对年轻雌性。
