Body mass and sex estimation from lower carnassial tooth morphometry in the endangered Iberian wolf (Canis lupus signatus): An ecomorphological analysis of sexual size dimorphism.

The Iberian wolf (Canis lupus signatus) is an endangered subspecies characterized by highly fragmented populations and increasing human-carnivore conflict across the Iberian Peninsula. Although body mass strongly influences predator-prey dynamics and ecological performance, quantitative assessments of sexual size dimorphism (SSD) and body mass (BM) variation in this subspecies remain scarce. Here, we conducted a morphometric analysis of the lower carnassial tooth (m1) in 78 historical and contemporary museum specimens (1900-2006) to evaluate its applicability for non-invasive body mass estimation and sex discrimination. We assessed the anteroposterior length (m1L) and blade length (m1BL) as potential proxies for BM and SSD. Multivariate analyses (MANOVA) based on m1L and m1BL revealed significant morphometric differences between sexes (Pillai's trace = 0.3488, p < 0.001), and Linear Discriminant Analysis produced a cross-validated classification accuracy of 79.07%. We further developed a predictive equation specifically calibrated for the Iberian wolf using m1L, achieving a mean absolute error of 2.44 kg and a mean absolute percentage error of 7.58% under leave-one-out cross-validation, demonstrating robust predictive performance for mature individuals. In immature specimens, the equation likely estimates expected adult body mass, consistent with earlier dental maturation relative to overall skeletal growth. Sexual size dimorphism was further supported by body mass estimates, with males being on average 21.4% (RBM) and 11.6% (EBM) heavier than females. Spatial analyses indicated morphological stability, with no significant differences in body mass between mature males from north and south of the Douro River, Portugal. Comparative analyses within Canis place the Iberian wolf within the range of variation of medium-sized wolves. Overall, carnassial morphometrics provide a robust and accurate approach for assessing ecomorphological traits, offering valuable data to support field monitoring, forensic applications, and conservation research in threatened canids.