We explored fluctuating asymmetry (FA) and morphological integration (MI) in the skull of the small, highly inbred and divergent Apennine bear (Ursus arctos marsicanus), to explore its uniqueness and investigate any potential effects of inbreeding depression. We used 3d geometric morphometrics contrasting 17 Apennine bears with other two large outbred bear populations (22 from Scandinavia and 9 from Kamchatka) as controls. Shape divergence and variability were explored by a PCA on aligned coordinates of 39 landmarks. Procrustes ANOVA, morphological disparity, and the Global Integration (GI) index were performed both to detect FA and to quantify shape variance and degree of MI. By remarking that Apennine bears share a highly divergent phenotype, we recorded the highest FA and deviation from self-similarity compared to the other two control populations. We conclude that Apennine bears are likely facing developmental instability as a consequence of inbreeding depression, whereas the divergent trait covariance pattern may represent a potential source of evolutionary novelties. We discuss the implications for the conservation and management of this imperiled taxon.
Thirty-nine 3d landmarks were collected on 3D models (from photgrammetry and CT scans) using the software Meshlab
Rscript, landmark coordinates:
- marsicano3D.csv # raw landmark coordinates
- Loy_et_al_Rcode.R #R code for GMM analysis
- Land.symm.csv # matrix containing matched pairs of symmetric landmarks
- orsolinks.csv # matrix defining links between landmarks