SUMMARYOntogenetic studies of vertebrate feeding performance can help address questions relevant to foraging ecology. Feeding morphology and performance can either limit access to food resources or open up new trophic niches in both aquatic and terrestrial systems. Loggerhead sea turtles are long-lived vertebrates with complex life histories that are marked by an ontogenetic shift from an oceanic habitat to a coastal neritic habitat, and a transition from soft oceanic prey to hard, benthic prey. Although considered durophagous and strong biters, bite performance has not been measured in loggerheads, nor has the ontogeny of bite performance been characterized. In the present study, we collected measurements of bite force in loggerhead turtles from hatchlings to adults. When subadults reach the body size at which the ontogenetic shift occurs, their crushing capability is great enough for them to consume numerous species of hard benthic prey of small sizes. As loggerheads mature and bite performance increases, larger and harder benthic prey become accessible. Loggerhead bite performance eventually surpasses the crushing capability of other durophagous carnivores, thereby potentially reducing competition for hard benthic prey. The increasing bite performance and accompanying changes in morphology of the head and jaws are likely an effective mechanism for resource partitioning and decreasing trophic competition. Simultaneous measurements of body and head size and the use of non-linear reduced major axis regression show that bite force increases with significant positive allometry relative to body size (straight carapace length, straight carapace width and mass) and head size (head width, height and length). Simple correlation showed that all recorded morphometrics were good predictors of measured bite performance, but an AICc-based weighted regression showed that body size (straight carapace width followed by straight carapace length and mass, respectively) were more likely predictors of bite force than head size morphometrics (head width and head length).
Las Guías Alimentarias Basadas en Alimentos (GABA) son un instrumento nacional de educación nutricional destinadas a la población general. En el contexto de alta prevalencia de enfermedades crónicas no transmisibles, relacionadas con dietas inadecuadas, buscan contribuir a alcanzar mejores estándares de alimentación. En el contexto americano, de alta prevalencia de sobrepeso y obesidad, las GABA forman parte de un conjunto de políticas gubernamentales para combatir estos problemas. El objetivo de este ensayo fue realizar un análisis comparativo de las GABA en nueve países americanos: Canadá, Chile, Estados Unidos, México, Paraguay, Colombia, Brasil, Uruguay y Argentina. Para la comparación se seleccionaron siete dimensiones generales: política, metodología, participación, mensajes, aspectos socioculturales, aspectos ambientales, y de implementación y evaluación, a partir de las recomendaciones para la elaboración de las GABA de organismos internacionales (FAO-OMS). Los resultados revelaron brechas en las guías de los países estudiados, destacando Brasil como uno de los países que pone mayor atención a la participación y a la incorporación de factores socioculturales en la producción de su documento. Mientras que Chile elude elementos como el género, el acceso y disponibilidad, la diversidad cultural, la sostenibilidad y los entornos alimentarios. Con guías alimentarias que abordan escasamente la propuesta FAO-OMS, es de esperar que en una futura actualización se consideren las dimensiones propuestas en un formato de desarrollo basado en la participación ciudadana, intersectorial y de expertos/as, fortaleciendo los aspectos socioculturales y ambientales.
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