The comparative effectiveness of rodents and dung beetles as local seed dispersers in Mediterranean oak forests

The process of seed dispersal of many animal-dispersed plants is frequently mediated by a small set of biotic agents. However, the contribution that each of these dispersers makes to the overall recruitment may differ largely, with important ecological and management implications for the population viability and dynamics of the species implied in these interactions. In this paper, we compared the relative contribution of two local guilds of scatter-hoarding animals with contrasting metabolic requirements and foraging behaviours (rodents and dung beetles) to the overall recruitment of two Quercus species co-occurring in the forests of southern Spain. For this purpose, we considered not only the quantity of dispersed seeds but also the quality of the seed dispersal process. The suitability for recruitment of the microhabitats where the seeds were deposited was evaluated in a multi-stage demographic approach. The highest rates of seed handling and predation occurred in those microhabitats located under shrubs, mostly due to the foraging activity of rodents. However, the probability of a seed being successfully cached was higher in microhabitats located beneath a tree canopy as a result of the feeding behaviour of beetles. Rodents and beetles showed remarkable differences in their effectiveness as local acorn dispersers. Quantitatively, rodents were much more important than beetles because they dispersed the vast majority of acorns. However, they were qualitatively less effective because they consumed a high proportion of them (over 95%), and seeds were mostly dispersed under shrubs, a less suitable microhabitat for short-term recruitment of the two oak species. Our findings demonstrate that certain species of dung beetles (such as Thorectes lusitanicus), despite being quantitatively less important than rodents, can act as effective local seed dispersers of Mediterranean oak species. Changes in the abundance of beetle populations could thus have profound implications for oak recruitment and community dynamics.

Hábitos alimenticios en alumnos y trabajadores de la Universidad Miguel Hernández

Objetivo: Describir los hábitos alimenticios de una comunidad universitaria. Material y métodos: Se llevó a cabo un estudio descriptivo transversal. El instrumento utilizado fue un cuestionario de frecuencias de consumo, administrado por entrevista personal a una muestra accidental de 147 personas. Constaba de cuatro secciones: 1) número de comidas y lugar donde se realizan, 2) patrones de consumo de los distintos grupos de alimentos, 3) modos de preparación de los alimentos, 4) datos de identificación y demográficos. Resultados: En comparación con el patrón de Vivanco y Palacios, nuestra muestra se caracteriza por: alto consumo de carnes (4 veces/semana), disminución del consumo de huevos (2v/sem.), incremento del consumo de hidratos de carbono complejos (5v/sem.), consumo ligeramente inferior de frutas (5v/sem.), ingesta insuficiente de verduras (4v/sem), legumbres (2v/sem) y pescados (2,5v/sem). Conclusiones y Recomendaciones: Atendiendo a los estudios referenciados, es conveniente disminuir el consumo de carnes, aumentando los aportes de pescados, verduras, hortalizas y legumbres, alimentos que, habiendo sido habituales en nuestra dieta mediterránea, parecen haber sido abandonados en beneficio de la conformación de una dieta que tiende a la homogeneización cultural.