A morphological comparison of jaguars and pumas in southern Mexico

Resumen

Jaguars (Panthera onca) and pumas (Puma concolor) are sympatric throughout the entire range of the jaguar. Pumas are smaller in areas where they are sympatric with jaguars and their body size is larger outside the distribution range of jaguars. This pattern has been explained as an effect that natural selection has promoted through character displacement to partially avoid competition. We examined and compared the body and craniodental measurements of sympatric jaguars and pumas from a tropical rainforest in southern Mexico. Data on body sizes were obtained from jaguars and pumas captured with foot snares. We implemented a principal component analysis (PCA) to evaluate variability in sizes between species and sexes and to characterize groups of individuals according to these morphological variables. Finally, we compared morphological variables using analyses of variance (ANOVAs) and pairwise comparisons using the Bonferroni adjustment. Body size and mass of female jaguars were similar to male pumas in southern Mexico. But, canines and mouth breadth were larger in female jaguars than in male pumas. In general, male jaguars were larger than male pumas and female jaguars were larger than female pumas, throughout the distribution of the jaguar. However, female jaguars and male pumas may have similar body mass and size in much of their sympatric distribution. Our results suggest that character displacement between jaguars and pumas might be expressed not only by their body size, but also by their skull size, the length and robustness of canines, and the mouth breadth, and these morphological differences allow for resource partitioning and the coexistence of these two species that have very similar ecological requirements.