homoplasmy

from The Century Dictionary.

• noun The quality or condition of being homoplastic; homomorphism.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Biol.) Resemblance between different plants or animals, in external shape, in general habit, or in organs, which is not due to descent from a common ancestor, but to similar surrounding circumstances.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the presence of the same mutation in all copies of mitochondrial or plastid DNA within a single cell or individual