Number of genes to analyze

[paul-bio]

Hi, I am learning BEAST2 these days. I figured out that the input genes has to be housekeeping gene. So I am trying to use all protein codeing gene in mitochondria (ex CO1-3, NAD1-6, ,,,,)

However I couldn't find how many genes are needed. Although I have 10 protein coding genes from mitochondria, there are 4 genes available on NCBI.

So does anyone can tell me the minimum number of gene? Does 4 genes might do?