Why do you think it can be difficult for scientists to determine whether an apparent relationship between species is an example of symbiosis? Use evidence from the article to support your answer.

The nature of the relationship isn’t always clear. For example, dolphins help people fish, but it’s not clear whether the dolphins respond to calls. This situation can make it difficult to determine whether the relationship is mutualistic or commensal.

Explanation:

answer from Plato

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.