sibling species

sibling species noun Biology.

1. one of two or more species that closely resemble one another but whose members cannot interbreed successfully.

sibling species in Science sibling species [sĭb′lĭng]

1. Any of two or more related species that are morphologically nearly identical but are incapable of producing fertile hybrids. Sibling species can only be identified by genetic, biochemical, behavioral, or ecological factors, and are thought to have become divergent very recently.