Physiological constraints and the influence of diet on fatty acids in the yolk of gentoo penguins, Pygoscelis papua

Abstract

Avian yolk fatty acids (FA) composition is influenced by two main factors: maternal diet and genetic factors that regulate FA metabolism. However, due to embryonic developmental requirements, yolk FA are thought to be physiologically constrained and less useful for dietary and trophic studies. We assessed the relative contributions of diet and physiological constraints in determining the yolk FA composition of a marine bird, the gentoo penguin (Pygoscelis papua) by comparing FA signatures of yolks and prey between a captive, controlled- feeding experiment and a wild population. Captive and wild yolk FA signatures differed even though both groups' yolk lipids were composed primarily of three FA (16:0, 18:0 and 18:1n-9). Differences were due to FA occurring in relatively low abundance, but which mirrored differences in the FA composition of diets. However, yolk FA signatures were correlated across three penguin species suggesting that common developmental constraints can be relatively more important than species-specific differences in diet or egg-laying physiology. While yolk FA are constrained, several minor components of yolk FA are reflective of diets and the calibration coefficients resulting from this study have the potential to be incorporated into predictive models and allow for quantitative dietary and trophic studies using FA analysis of penguin egg yolks.

Egg yolk fatty acids as a proxy to quantify diets of female Spectacled Eiders (Somateria fischeri)

“…The CCs for these three FA were much higher for penguins than eiders and might be explained by an increase in de novo synthesis of these FA by penguins prior to egg formation (Groscolas 1990). These, and other FA such as 20:4n-6 with large CCs, are also likely influenced by differential rates of mobilization from diets and maternal adipose tissue (Polito et al 2012). Differences in CCs between species may also be explained by differences in diet.…”

“…Calibration coefficients (CCs) for diet to egg yolk fatty acids (FA) from Spectacled Eider (Somateria fischeri) eggs collected in 2008 (mean ± 1 SD). CCs for diet to adipose tissue for Spectacled Eider males from Wang et al (2010) and Gentoo Penguins (Pygoscelis papua) (Polito et al 2012) shown for comparison. The horizontal line at 1 represents a 1:1 incorporation of FA from the diet into the egg yolk and adipose tissue.…”

“…To determine how transferable CCs are between avian species, we estimated the diets of Spectacled Eiders from egg yolk in 2008 using Gentoo Penguin egg yolk CCs from Polito et al (2012). Four FA subsets similar to the ones listed above were applied in the QFASA model.…”

“…These CCs are then used in the QFASA model to weight individual FA in diet estimation procedures (Iverson et al 2004Wang et al 2010). In marine birds, CCs have been developed from adipose tissue of captive Common Murre (Uria aalge (Pontoppidan, 1763)) chicks ), Spectacled Eider and Steller's Eider (Polysticta stelleri (Pallas, 1769)) adults (Wang et al 2010), Tufted Puffin (Fratercula cirrhata (Pallas, 1769)) chicks (Williams et al 2009), Rhinoceros Auklet (Cerorhinca monocerata (Pallas, 1811)) chicks (A.S. Kitaysky unpublished data), adipose tissue and blood plasma of Yellowlegged Gull (Larus michahellis Naumann, 1840) adults (Käkelä et al 2009(Käkelä et al , 2010, and from the egg yolk of Gentoo Penguins (Pygoscelis papua (Forster, 1781)) (Polito et al 2012).…”

“…In addition to stomach oils, egg yolks are a potential source of lipid from which maternal diets may be inferred (e.g., Polito et al 2012). Differences in diet have been shown to influence polyunsaturated FA profiles in avian egg yolk (Surai et al 2001b) and some components of egg yolk FA reflect maternal diet (Polito et al 2012).…”