(e) Statistics
Relative abundance ratios were calculated in Proteome Discoverer and the data were both row and column (i.e., protein and sample) normalized to an average value of 100. Data are shown as the mean ± SE. A studentt -test was used to find variation between feather (δ2Hf), claw (δ2Hc) hydrogen isotope ratios, and physiological response variables (i.e., CPV, T, FS, and BM) measured in two groups. We initially compared normalized abundances for each protein between residents and migrants using standard two sample t -test, followed by multiple correction test based on a sequential goodness of fit (SGoF) metatest (Carvajal- Rodríguez, Uña-Álvarez, & Rolán-Álvarez, 2009). Because of small sample size, individual protein abundance comparisons exhibit large sample variance, and small fold changes. Stringent multiple testing correction methods to calculate false discovery rate (FDR) for multiple repeated t -tests are often not suitable for small sample size proteome experiments. In such condition a liberal multiple testing correction methods SGoF metatest can be a valuable approach for multitest adjustment. All statistical analyses were conducted using R (version 3.2.0) or GraphPad Prism version 6, and a p value <0.05 was considered significant.