阿拉善荒漠区两种优势跳鼠种间营养生态位

Interspecific trophic niches of two dominant jerboas in the Alax Desert

营养生态位作为生态位理论的重要维度之一,不仅能够表现出物种的营养需求特征,而且可以反映物种在生态系统中的营养层级、功能地位以及物种间的营养关系。动物不同组织中的碳、氮稳定同位素比值可反映某一物种在不同时间段的食性信息,因而对探讨物种间摄食、栖息地资源利用和营养生态位的变化具有重要指示作用。以2017年在阿拉善荒漠实验区采用铗日法所捕获的三趾跳鼠(Dipus sagitta)和五趾跳鼠(Allactaga sibirica)为研究对象,测定其脱脂毛发与骨骼组织的δ^(13)C和δ^(15)N比值,分析探讨2种小型啮齿动物的营养级与营养生态位变化以及摄食策略与资源分配机制。结果表明:无论从长期时间尺度(一生)还是短期时间尺度(季节)分析,结果都一致表现出三趾跳鼠与五趾跳鼠种间营养生态位重叠面积(OA)值为0‰^(2),种间营养生态位发生分离;三趾跳鼠的营养级显著低于五趾跳鼠的营养级,但其营养生态位面积却大于五趾跳鼠;随着季节的变化,三趾跳鼠与五趾跳鼠的摄食范围和营养生态位面积均呈现出春季最大,夏季减小,秋季再增加的趋势。两种跳鼠的营养生态位变化与摄食策略符合生态位分化假说,二者通过种间营养生态位分化实现同域共存。

Trophic niche is one of the important dimensions of niche theory.It reflects the nutritional needs of species,trophic level,functional status and nutritional relationship of interspecies in the ecosystem.Theδ^(13)C andδ^(15)N in different tissues of animals reflect the species feeding information in different periods.Therefore,this is an important indicator for exploring feeding change,habitat resource utilization and trophic niche of interspecies.We analyzed theδ^(13)C andδ^(15)N ratio in hair and skeletal tissue of northern three-toed jerboa(Dipus sagitta)and mongolian five-toed jerboa(Allactaga sibirica)in 2017 in Alxa Desert,the Inner Mongolia,China.We compared the trophic level and niche change,feeding strategy and resource allocation mechanism of two rodent species.The results showed that,both at long-term(lifetime)and short-term(season)scales,two species presented an interspecific trophic niche separation.The trophic level of Dipus sagitta was significantly lower than Allactaga sibirica,but trophic niche area of Dipus.sagitta was larger than Allactaga sibirica.The feeding range and trophic niche area of Dipus sagitta and Allactaga sibirica showed a common trend of the maximum in spring,decreasing in summer,and increasing in autumn.The changes in trophic niches and feeding strategies of two rodents were consistent with the niche differentiation hypothesis.Two rodent species coexisted by trophic niche differentiation in Alax Desert.