稳定同位素示踪东北地区晚更新世真猛犸象的摄食行为

摘要

真猛犸象(Mammuthus primigenius)是晚更新世古北界最典型的动物之一,曾广泛分布于欧亚大陆和北美地区.了解真猛犸象的食物结构对探讨其演化乃至灭绝极具科学意义.目前,通过真猛犸象化石及伴生动物群的C、N稳定同位素分析揭示真猛犸象的食物结构,国际上已有不少报道,却缺少东亚地区的研究案例.为此,本文以黑龙江省大庆博物馆馆藏的东北地区晚更新世真猛犸象及伴生动物群的骨骼化石为研究对象,开展了包括真猛犸象、披毛犀、马科、牛科等9种33个个体的C、N稳定同位素分析.研究结果显示:在所有动物中,真猛犸象具有最高的δ15N值,高于植食和肉食动物.显然,与其他动物相比,真猛犸象具有独特的摄食行为,可能受到生态环境、生理特点、食粪行为等多个因素的影响.结合国际上已发表的关于真猛犸象化石的同位素数据,笔者发现:真猛犸象的食物来源较为稳定,食物专门化程度较高.由此可见,真猛犸象具有的独特摄食行为,可能是其不能很好适应更新世晚期环境和气候变化而造成灭绝的动因之一.%Mammuthus primigenius (woolly mammoth),is the most characteristic mammal in Late Pleistocene,with an extensive Holarctic distribution.The foraging ecology of Mammuthus primigenius plays a significant role in their evolution history and even extinction.Until now,large amounts of researches on diet and ecology using stable isotope had been applied on the Mammuthus primigenius,but the data from East Asia was meagre.Daqing Museum is located in Daqing City,Heilongjiang Province,China (46°58′N,125°15′E),which is famous for abundant Quaternary mammal fossils,especially Mammoth Fauna in Late Pleistocene.All the samples in this study are collected from sites around Daqing City,though precise sites and layers are not clear.Based on faunal assemblage,the age of these samples is currently estimated to be 40～ 10ka.In this study,stable carbon and nitrogen isotope analysis is applied to 33 animal remains,from 9 species,including as Mammuthus primigenius,Coelodonta antiquitatis,Equus przewalskii,Bovidae,Cervidae,Ursus arctos,Felis sp.and Vulpes vulpes.Except for Felis sp.,all animals in this study are fed on pure C3 diet.Mammuthus primigenius in this study shows highest δ15N values (10.4± 1.3‰,n =6),much higher than other herbivores (represented by Equus przewalskii and Cervidae,5.8±1.1‰,n=9) even carnivorans (represented by Ursus arctos and Felis sp.,9.4± 1.0‰,n=6).Coelodonta antiquitatis (n=3) and Bovidae (n=5) also show relatively higher δ15N values,which are averaged by 7.6±2.5‰ and 8.1±1.9‰,some individuals are even similar to Mammuthus primigenius.Coelodonta antiquitatis and Bovidae have various food resource,partly overlapped with Mammuthus primigenius.Besides,δ13C values of Mammuthus primigenius are lowest among all the fauna (-21.6±0.3‰,n =6).Therefore,Mammuthus primigenius apparently shows specialized foraging behavior compared to other mammals,which may be influenced by three factors,including foraging habitat,physiology and coprophagy.We further collect previously published carbon and nitrogen results from Eastern Europe,Siberia and North America.The data show that Mammuthus primigenius has the highest δ15N values,and relatively lower δ13C values compared to coexisting herbivores (Coelodonta antiquitatis,Equidae,Bovidae and Cervidae).The carbon and nitrogen isotopic data of Mammuthus primigenius represent a stable but narrow dietary breadth,also imply that they may occupy a solid and limited ecological niche.Therefore,a specialized diet and high sensitivity to environmental fluctuations of Mammuthus primigenius at the end of the Last Ice Age might be one of the mainspring of their extinction.