Mean (±SD)values of δ¹³C (A) and δ¹⁵N (B) for bone from the skulls of male and female sea lions collected in three different regions of the Galapagos archipelago.

<p>Regions with different superscript (lower-case letters) are statistically different in their mean values according to the Scheffe's post hoc test. Vertical bars show standard deviation.</p

Area of the isotopic niche of Galapagos sea lions in the three different regions of the archipelago.

<p>Ellipse areas (solid lines)calculated with SEA_C using the bivariated isotopic values (solid circles) of males and females from each region(West, Central and South).</p

Map of the Galapagos archipelago showing the islands where sea lion skulls were collected and the chlorophyll levels.

<p>Chlorophyll values are the cumulative average values of chlorophyll-a concentration (mg/m³) from 1 September 1997 to 31 August 2001 derived from SeaWiFS Project (<a href="http://oceancolor.gsfc.nasa.gov" target="_blank">http://oceancolor.gsfc.nasa.gov</a>). The hydrogeographic regions, in agreement with Ruttenberg et al.[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147857#pone.0147857.ref042" target="_blank">42</a>], are denote by the names in brackets.</p

Predator and potential preys’ stable isotope signal.

<p>Biplot of the isotopic contents of δ¹⁵N and δ¹³C of the South American sea lion (<i>Otaria flavescens</i>), the South American fur seal (<i>Arctocephalus australis</i>) and their main potential preys in Uruguay. Prey species were captured in the pelagic and neritic areas of the Uruguayan continental shelf and their names are fully indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080019#pone-0080019-t001" target="_blank">Table 1</a>. Error bars correspond to standard deviations. These averages and standard deviations were used as input for the mixing models.</p

Diet composition comparison by scat and Bayesian mixing models with and without prior information.

<p>Diet composition of the South American fur seal (<i>Arctocephalus australis</i>) (a) and South American sea lion (<i>Otaria flavescens</i>) (b) in Isla de Lobos, Uruguay estimated by scat analysis (light grey bars), Bayesian mixing modes with uninformative (SIMM-UP; dark grey bars) and informative (SIMM-IP; black bars) priors. Mixing models were obtained with the library SIAR in the R software [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0080019#B27" target="_blank">27</a>]. The error bars for the scat analysis were obtained by bootstrap.</p