Subspecies inflation hampers conservation efforts: a case study on wall lizards

The common practice of using subspecies as conservation targets raises the question of whether efforts are focused on preserving conspicuous components of the species’ phenotypic variability rather than evolutionarily significant units. To address this question, in this study we performed a comprehensive morphological and genetic assessment on all the subspecies of wall lizard described for the Aeolian Archipelago (Italy) to determine whether they represent distinct evolutionary lineages and/or discrete phenotypic partitions. Further, we applied a monophyly test to 70 subspecies belonging to seven wall lizard species occurring in Italy, based on our results and on previous phylogeographic studies. We found that none of the Aeolian subspecies represents a distinct evolutionary lineage, despite some morphological differentiation of island populations across the archipelago, suggesting a very recent origin of island populations and of the observed phenotype variation. Across seven wall lizard species, tests revealed that lizard subspecies rarely (< 9% of cases) match evolutionary units. This study demonstrates that intraspecific taxonomy of wall lizards is a poor predictor of phylogeographic partitions and evolutionary units, and therefore of limited use (if not dangerous) for defining conservation and management units. A better approach would be relying on the integration of genomic and phenotypic data to assess the evolutionary significance and conservation value of phenotypic and genetic units within species.