What is used as evidence for the idea that the domain eukarya evolved from unicellular organisms?

The idea that the eukaryotes evolved from the unicellular organisms. This idea is based on the evidence of the endosymbiosis. The endosymbiosis is based on the concept that the mitochondria and the chloroplast have their own DNA. All the eukaryotic animal cells have mitochondria. It is believed that the mitochondria and chloroplast were separate unicellular organisms before they were engulfed by other unicellular bacteria and started residing inside them.

Hence, the evidence for the given idea is that the mitochondria and chloroplasts have their own DNA.