Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: evidence from quantitative fatty acid signature analysis
Sex differences in grey seal diet reflect seasonal variation in foraging behaviour and reproductive expenditure: evidence from quantitative fatty acid signature analysis
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DOI：
10.1111/j.1365-2656.2007.01215.x
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发表时间：
2007-05-01
影响因子：
4.8
通讯作者：
Blanchard, Wade
中科院分区：
文献类型：
--
作者：
Beck, Carrie A.;Iverson, Sara J.;Blanchard, Wade
1.食物的种内变异是物种生态位宽度的重要组成部分。我们测试的假设，性别差异的季节性觅食行为和能量储存的性大小的二型灰海豹Halichoerus grypus（Fabrisius 1971）反映在饮食和生态位宽度的差异。饮食组成估计为496成年（226名男性，270名女性）和91名青少年（46名男性/45名女性，所有6个月大）灰海豹采样1993年和2000年之间使用定量脂肪酸签名分析。生态位宽度和重叠分别采用Shannon-Weaver多样性指数（H '）和Morisita-Horn指数（C-H）进行估算.沙矛Ammodytes us（Reinhardt 1837）和红鱼sp.（Cuvier 1829）在性别和年龄组的饮食中占很高的比例。然而，成年雄性的饮食在所有季节都明显更多样化（H '：雄性0.36 +/- 0.007 vs.雌性0.28 +/- 0.007），春季的能量密度（雄性5.3 +/- 0.07 kJ g（-1）vs.雌性5.6 +/- 0.09 kJ g（-1））低于成年雌性。季节和性别解释了大多数观察到的成人饮食的变化，但有显着的性别季节的相互作用。这些差异是最明显的在繁殖后（春季）觅食期间，能量收购是重要的女性恢复营养商店需要支持怀孕。春季雌性选择的猎物种类较少，但质量较高.幼海豹的食性没有性别差异。虽然许多物种与成虫的食物重叠，但幼鱼的生态位宽度（H '：0.41 +/- 0.014，n = 91）显著大于成虫的生态位宽度（H'：0.30 +/- 0.011，n = 115）。幼鱼饮食的能量密度（5.3 +/- 0.04 kJ g（-1））也低于成年鱼（5.6 +/- 0.09 kJ g（-1）），表明这些年轻和相对幼稚的捕食者的选择性较低。特定性别的季节性饮食变化对应于季节性变化的潜水行为和成年男性和女性的身体能量积累率。性别特异性生殖需求似乎是这种大型海洋食肉动物季节性觅食生态产生种内变异的主要因素。然而，性别差异的广度和能量含量的饮食也表明身体大小二型性的影响，作为一个因素，塑造这个物种的饮食。
1. Intraspecific variation in diet can be an important component of a species niche breadth. We tested the hypothesis that sex differences in seasonal foraging behaviour and energy storage of sexually size dimorphic grey seals Halichoerus grypus (Fabrisius 1971) are reflected in differences in the diet and niche breadth. Diet composition was estimated for 496 adult (226 males, 270 females) and 91 juvenile (46 males/45 females; all 6 months old) grey seals sampled between 1993 and 2000 using quantitative fatty acid signature analysis. Niche breadth and overlap were estimated using the Shannon-Weaver diversity index (H') and the Morisita-Horn index (C-H), respectively.2. Sand lance Ammodytes dubius (Reinhardt 1837) and redfish Sebastes sp. (Cuvier 1829) accounted for a high proportion of the diet in both sexes and age groups. However, the diets of adult males were significantly more diverse across all seasons (H': males 0.36 +/- 0.007 vs. females 0.28 +/- 0.007) and less energy dense in spring (male 5.3 +/- 0.07 kJ g(-1) vs. females 5.6 +/- 0.09 kJ g(-1)) than those of adult females.3. Season and sex explained most of the observed variation in adult diets, but there were significant sex-season interactions. These differences were most evident during the post-breeding (spring) foraging period when energy acquisition is important to female recovery of nutrient stores needed to support pregnancy. Females selected fewer and higher quality prey species in spring than males.4. There were no sex differences in the diets of juvenile grey seals. Although many of the species overlapped with those eaten by adults, juvenile niche breadth (H': 0.41 +/- 0.014, n = 91) was significantly broader than that of adults (H': 0.30 +/- 0.011, n = 115). Juvenile diets were also of lower energy density (5.3 +/- 0.04 kJ g(-1)) than those of adults (5.6 +/- 0.09 kJ g(-1)), suggesting less selectivity in these young and relatively naive predators.5. Sex-specific seasonal changes in diet correspond to seasonal changes in diving behaviour and rate of body energy accumulation of adult males and females. Sex-specific reproductive requirements appear to be a primary factor generating the intraspecific variation in the seasonal foraging ecology of this large marine carnivore. However, sex differences in the breadth and energy content of diets also suggest the influence of body-size dimorphism as a factor shaping the diet of this species.