More than twenty years of geometric morphometrics and the species conservation. A tribute to Dennis E. Slice

Management and conservation strategies of endangered species with a wide geographical range are strictly dependent on the identification of the most critical populations in need of specific and urgent conservation actions. While genetic data provide the general framework for the identification of Evolutionary Significant Unit (ESU), morphological information can still depict both divergent taxonomic units and their unique adaptive traits. Digital imaging combined within the geometric morphometrics (GMM) frame-work permit an holistic approach to the analysis of complex anatomical structures whose intra and interspecific variation might inform species taxonomy and conservation. We provide examples based on the study of mammalian skulls to demonstrate that GMM data can be quite relevant to fll the gap between taxonomic research and conservation practice. We evidenced a strong phenotypic divergence in the Apennine brown bear (Ursus arctos marsicanus) that was contrasting with conclusions drawn from molecular data. This will inform potential reinforcement also in the light of results obtained on fluctuating asymmetry in European brown bear populations. The analyses of shape and allometric trajectories in three dolphins equally demonstrated significant differences between Mediterranean and the extra-Mediterranean populations, supporting the institution of unique Management Units. Divergent criptic populations of the genetically homogenous Eurasiatic otter (Lutra lutra) were equally identified for the skull shape of the European populations. These studies greatly own their achievements to the pioneer works of Dennis E. Slice on the vertebrate skull morphometrics, and will hopefully contribute to establish a pragmatic link between morphological research and conservation biology