What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains

Molecular Evidence has recently made it necessary to assign the prokaryotes to either of two different domains.

Explanation:

There was an OLD 5 classification system : Monera Protists Plants Fungi

2. NEW 3 domain system reflects:

A greater understanding of evolution Molecular evidence

Thus, the new domain includes:

Prokaryote : Bacteria Prokaryote : Achaebacteria

3. Eukaryotes:

Protists Plants Fungi Animals