The fitness consequences of bearing domatia and having the right ant partner: experiments with protective and non-protective ants in a semi-myrmecophyte

The fitness advantage provided by caulinary domatia to myrmecophytes has never been directly demonstrated because most myrmecophytic species do not present any individual variation in the presence of domatia and the removal of domatia from entire plants is a destructive process. The semi-myrmecophytic tree, Humboldtia brunonis (Fabaceae: Caesalpinioideae), is an ideal species to investigate the selective advantage conferred by domatia because within the same population, some plants are devoid of domatia while others bear them. Several ant species patrol the plant for extra-floral nectar. Fruit production was found to be enhanced in domatia-bearing trees compared to trees devoid of domatia independent of the ant associate. However, this domatium effect was most conspicuous for trees associated with the populous and nomadic ant, Technomyrmex albipes. This species is a frequent associate of H. brunonis, inhabiting its domatia or building carton nests on it. Ant exclusion experiments revealed that T. albipes was the only ant to provide efficient anti-herbivore protection to the leaves of its host tree. Measures of ant activity as well as experiments using caterpillars revealed that the higher efficiency of T. albipes was due to its greater patrolling density and consequent shorter lag time in attacking the larvae. T. albipes also provided efficient anti-herbivore protection to flowers since fruit initiation was greater on ant-patrolled inflorescences than on those from which ants were excluded. We therefore demonstrated that caulinary domatia provide a selective advantage to their host-plant and that biotic defence is potentially the main fitness benefit mediated by domatia. However, it is not the sole advantage. The general positive effect of domatia on fruit set in this ant-plant could reflect other benefits conferred by domatia-inhabitants, which are not restricted to ants in this myrmecophyte, but comprise a large diversity of other invertebrates. Our results indicate that mutualisms enhance the evolution of myrmecophytism

An investigation of social dynamics in Cape buffalo and implications for disease transmission at wildlife/domestic interfaces in the Great Limpopo Transfrontier Conservation Area

In this work experimental analysis was carried out between incidence angle an Kerr signal intensity, that influences in the hystereteresis shape behavior, which establishes a direct relationship between both for longitudinal configuration on the Kerr Magnetometer. The results show a better behavior of the curve for the defined range from 10° to 60° of incident angle.En este trabajo se realiza un análisis experimental de la relación entre el ángulo de incidencia y la intensidad de la señal Kerr, que influye en la forma del ciclo de histéresis, planteándose una relación directa entre ambos para la configuración longitudinal en el magnetómetro Kerr. Los resultados obtenidos evidencian un mejor comportamiento de dicha curva para el rango comprendido entre 10° y 60 ° del ángulo de incidencia