Dados do Trabalho

Título:

ALLOMETRIC TRAJECTORIES IN THE SKULL OF NEOTROPICAL FELIDS (CARNIVORA: FELIDAE)

Resumo:

Allometric patterns are essential for studying the evolutionary trends of felids’ skull shape. This is due to a size-dependent association between the biting performance and resistance to force application. Using geometric morphometrics, we evaluated and compared the overall intraspecific and interspecific patterns of static allometry in the ventral view of the skull of five species of Neotropical felids: Leopardus wiedii, L. pardalis, Puma concolor, Herpailurus yagouaroundi and Panthera onca. We chose these species due to their body size variation and availability in museum collections. Also, they present a range of feeding ecologies, from small generalists to large hipercarnivores. We landmarked a total of 506 adult specimens (96 L. wiedii, 127 L. pardalis, 113 H. yagouaroundi, 122 P. concolor and 48 P. onca). We have found that the allometric trends (slopes) are statistically different between species (shown by the interaction between size and species in a linear model of shape variation). This means that the different felid species do not follow the same allometric path in shape space. We performed a between-species pairwise comparison of allometric vectors (by angular differences). Parallel intraspecific allometric vectors are expected to present angular differences equal to or near 0. We found that none of the species pairings present paralell slopes. There are also considerable differences in the magnitude of allometry between species (R² L. wiedii = 0.039, R² L. pardalis = 0.073, R² H. yagouaroundi = 0.070, R² P. concolor = 0.128, R² P. onca = 0.241). In L. wiedii, the largest specimens present proportionally shorter carnassials, thinner olfactory bula, smaller occipital condyles, and larger zygomatic arches than the smallest. All species share some regions of the skull that are affected, but not all. From smaller to larger species, they all present a size increase in the zygomatic arches and a decrease in the occipital condyles. These zygomatic arches differences are more pronounced in P. concolor and P. onca than in the smaller cats. All species but L. wiedii share the decrease of the auditory bullae and upper carnassials relative sizes in the largest specimens. Herpailurus yagouaroundi and P. concolor patterns present similarities in the relative dimensions of skull shape, with the smallest specimens presenting a more globular skull than the largest. These preliminary results are promising and bring to light the necessity to look into intraspecific variation comparatively. Analyses of other bones and skull views, along with the investigation of the selective pressures that favour these slope differences will be considered in future studies.

Financiamento:

FAPERJ, CAPES, CNPq

Área

Anatomia e Morfologia