Though not directly cited on their site, the Mammal Diversity Database (MDD) follows Hope et al. (2016, cited below), who tested three hypotheses using mitochondrial DNA from red squirrels (Tamiasciurus sp.) found along the west coast. Their first hypothesis (H1) was that there are three species of red squirrel: T. hudsonicus, T. mearnsi, and T. douglasii. This was the standard taxonomy at the time followed by most authorities. Ultimately, T. douglasii was the only well-supported species in their analysis. Hope et al. (2016) found the differences between T. douglasii and T. mearnsi to be untenable. The mitochondrial lineage found in the geographically-isolated T. mearnsi (which occurs in Baja California) extends throughout the range of T. douglasii in Vancouver Island. Their divergence is "minimal". However, Mearns's Squirrel is a conservation-dependent population currently considered Endangered by the IUCN Red List (de Grammont & Cuarón, 2018). As employed by Hope et al. (2016), this taxonomic merge reassigns T. mearnsi as the subspecies T. douglasii mearnsi to preserve its conservation status.
Hope AG, Malaney JL, Bell KC, Salazar-Miralles F, Chavez AS, Barber BR, and Cook JA. "Revision of widespread red squirrels (genus: Tamiasciurus) highlights the complexity of speciation within North American forests". Molecular Phylogenetics and Evolution 100 (2016) 170–182. https://doi.org/10.1016/j.ympev.2016.04.014 (Vínculo)
Los desacuerdos no intencionados ocurren cuando un grupo padre (B) se adelgaza al cambiar un grupo hijo (E) a otra parte del árbol taxonómico, provocando que las Identificaciones existentes del grupo padre sean interpretados como desacuerdos con las Identificaciones existentes del grupo hijo cambiado.
Identification
La ID 2 del taxón E será un desacuerdo no intencionado con la ID 1 del taxón B después del intercambio de ancestros
Si el adelgazamiento del grupo padre provoca más de 10 desacuerdos no intencionados, deberías dividir el grupo padre después de intercambiar el grupo hijo para substituir las identificaciones existentes del grupo padre (B) con identificaciones con las que no esté en desacuerdo,