[sghi]

So this is the research area that I currently work in, albeit with a disease ecology perspective rather than a biochemistry one. I've had a quick read of it and and although it does seem to track other research that has been done ("Why are behavioral and immune traits linked?" by Lopes 2017 is a nice review) I'd love to see some power analyses - the sample size seems pretty small for something as complex as this question. The study I'm helping with now has a minimum sample size in the hundreds, for instance, for a broadly similar question. PCA-ing a few tests together is pretty common, but also comes with a lot of potential biases (see "Avoiding the misuse of BLUP in behavioural ecology" by Houslay and Wilson if anyone is interested!)