Acertain sea slug, elysia chlorotica, "steals" chloroplasts from algae it normally feeds upon, and then uses the chloroplasts to conduct photosynthesis during times of low food availability. scientists found that the slug carries a chloroplast-maintenance gene in its genome, a gene identical to one found in the algae. the process by which the slug first acquired the gene is called what?

Horizontal gene transfer

Explanation:

Horizontal gene transfer or lateral gene transfer is when an organisms of different species can acquire a gene from a different one. This process is well understood in bacteria and is responsible for the appearence of antibiotic resistant bacteria. Bacteria can take DNA fragments through a process known as transformation, but this is less common in eukaryotes. Gene transfer agents like viruses could carry the gene from one specimen to the other. Another way could be Horizontal transposon transfer but the exact mechanisms behind it are still under research.