Hobson Keith A, Quirk Travis W
a Environment Canada , Saskatoon , SK , Canada.
Isotopes Environ Health Stud. 2014;50(3):300-6. doi: 10.1080/10256016.2014.867852. Epub 2014 Feb 7.
An important prerequisite for the effective use of stable isotopes in animal ecology is the accurate assessment of isotopic discrimination factors linking animals to their diets for a multitude of tissue types. Surprisingly, these values are poorly known in general and especially for mammalian carnivores and omnivores in particular. Also largely unknown are the factors that influence diet-tissue isotopic discrimination such as nutritional quality and age. We raised adult and juvenile striped skunks (Mephitis mephitis) in captivity on a constant omnivore diet (Mazuri Omnivore A 5635). Adults (n=6) and juveniles (n=3) were kept for 7 months and young (n=7) to the age of 50 days. We then examined individuals for stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope values of hair, nails, lipid, liver, muscle, bone collagen and the plasma, and cellular fractions of blood. Discrimination values differed among age groups and were significantly higher for young compared with their mothers, likely due to the effects of weaning. Δ(15)N isotopic discrimination factors ranged from 3.14 (nails) to 5.6‰ (plasma) in adults and 4.3 (nails) to 5.8‰ (liver) for young. For Δ(13)C, values ranged from-3.3 (fat) to 3.0‰ (collagen) in adults and from-3.3 (fat) to 2.0‰ (collagen) in young. Our data provide an important tool for predicting diets and source of feeding for medium-sized mammalian omnivorous adults integrated over short (e.g. liver, plasma) through long (e.g. collagen) periods and underline the potential effects of age on isotopic values in omnivore diets.
在动物生态学中有效使用稳定同位素的一个重要前提是准确评估将动物与其多种组织类型的食物联系起来的同位素分馏系数。令人惊讶的是，一般来说这些值知之甚少，尤其是对于哺乳动物食肉动物和杂食动物而言。同样很大程度上未知的是影响食物 - 组织同位素分馏的因素，如营养质量和年龄。我们将成年和幼年条纹臭鼬（Mephitis mephitis）圈养在恒定的杂食性饮食（Mazuri杂食动物A 5635）中。成年个体（n = 6）和幼年个体（n = 3）饲养7个月，幼崽（n = 7）饲养到50天大。然后我们检测了个体毛发、指甲、脂质、肝脏、肌肉、骨胶原蛋白、血浆以及血液细胞部分的稳定碳（δ(13)C）和氮（δ(15)N）同位素值。分馏值在不同年龄组之间存在差异，幼崽的分馏值明显高于它们的母亲，这可能是断奶的影响所致。成年个体的Δ(15)N同位素分馏系数范围为3.14（指甲）至5.6‰（血浆），幼崽的范围为4.3（指甲）至5.8‰（肝脏）。对于Δ(13)C，成年个体的值范围为 - 3.3（脂肪）至3.0‰（胶原蛋白），幼崽的范围为 - 3.3（脂肪）至2.0‰（胶原蛋白）。我们的数据为预测中型哺乳动物杂食性成年个体在短时间（如肝脏、血浆）到长时间（如胶原蛋白）内的食物和觅食来源提供了一个重要工具，并强调了年龄对杂食性饮食中同位素值的潜在影响。
