Resumen del producto

Mammalian skulls are complex and display considerable structural diversity as natural selection shapes distinct traits in unique environments. Since form is constrained by distinct genetic, developmental, and functional factors, different skull modules respond uniquely to distinct environment and selection forces. Due to the high degree of philopatry, their feeding strategy, and the extended lactation period of adult females, California and Galapagos sea lions display well-defined genetic population structures throughout their distributions. Ecological components and social interactions vary between these species, making them ideal for examining the forces that drive skull morphology evolution. We employed geometric morphometric methods to assess morphological variability between different pinniped populations and species. We identified significant differences between California sea lions and Galapagos sea lions that derive from differences in the development of distinct skull modules. In California sea lions, we were able to distinguish between most neighboring populations, with the majority of the morphological differences occurring in the mastoid process, the anterior zone of the face, the zygomatic arches, and the sagittal crest. Considering the early ontogenetic development of the basicranium, we argue that the morphological variability of the Gulf of California populations reflects a directional selection process. In contrast, the low morphological variability in the basicranium of Pacific coast populations reflects the fact that selection pressures in the region are normalizing. Morphological variation in the face and jaws reflect the impact of environmental factors on skull shape.

Palabras clave: Morfología craneal; morfometría geométrica; Zalophus californianus

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx