ABSTRACT
Animal seed dispersal provides an important ecosystem service by strongly benefiting plant communities. There are several theoretical studies on the ecology of plant-animal seed-disperser interactions, but few studies have explored the evolution of this mutualism. Moreover, these studies ignore plant life history and frugivore foraging behaviour. Thus, it remains an open question what the conditions for the diversification of fruit traits are, in spite of the multitude of empirical studies on fruit trait diversity. Here, we study the evolution of fruit traits using a spatially explicit individual-based model, which considers the costs associated with adaptations inducing dispersal by frugivory, as well as frugivore foraging behaviour and abundance. Our model predicts that these costs are the main determinants of the evolution of fruit traits and that when the costs are not very high, the evolution of larger fruit traits (e.g. fleshy/colourful fruits) is controlled by the choosiness and response thresholds of the frugivores as well as their numerical abundance.
Subject(s)
Biological Evolution , Fruit/physiology , Seed Dispersal , Animals , Feeding Behavior , Fruit/anatomy & histology , Trees/anatomy & histology , Trees/physiologyABSTRACT
La mayor supervivencia de los enfermos de sida gracias a la continua evolución de las terapias aplicadas, ha condicionado la aparición de nuevas patologías asociadas a la enfermedad, así como una importante variación tanto en la incidencia como en la prevalencia de las clásicamente descritas.La asociación del sida con el carcinoma de pulmón es un punto controvertido. Aparece en personas jóvenes, con historia de tabaquismo. Es independiente de las cifras de linfocitos CD4 en sangre, presentándose en el momento del diagnóstico en estadios muy avanzados con una supervivencia media de 10 meses.Histológicamente corresponden con mayor frecuencia a adenocarcinomas, en general poco diferenciados y con una alta tasa de replicación.Conocer este hecho es fundamental para el radiólogo dado que ante una masa pulmonar con un crecimiento rápido, debe incluir el carcinoma de pulmón en el diagnóstico diferencial. Esto conlleva una mejor orientación clínica, evitando demoras en el diagnóstico con la consiguiente repercusión en la evolución y el pronóstico de la enfermedad.Presentamos cuatro casos de carcinoma de pulmón en enfermos VIH +, cuyos diagnósticos histológicos corresponden a dos adenocarcinomas (uno de ellos variedad adenocarcinoma mucinoso), un tumor de células grandes y un carcinoma epidermoide, diagnosticados en nuestro centro. Se describen los hallazgos radiológicos tanto con técnica convencional como con TC y se compara con la bibliografía publicada (AU)
Subject(s)
Adult , Female , Male , Middle Aged , Humans , Carcinoma/complications , Carcinoma/diagnosis , Carcinoma , Carcinoma , Lung/pathology , Lung , Lung , Acquired Immunodeficiency Syndrome/complications , Acquired Immunodeficiency Syndrome/diagnosis , Acquired Immunodeficiency Syndrome , CD4 Immunoadhesins/administration & dosage , CD4 Immunoadhesins , Feline Acquired Immunodeficiency Syndrome/complications , Feline Acquired Immunodeficiency Syndrome , Feline Acquired Immunodeficiency Syndrome , Adenocarcinoma, Mucinous/complications , Adenocarcinoma, Mucinous , Adenocarcinoma, Mucinous , Diagnosis, Differential , Tomography, X-Ray Computed/methods , Bronchoscopy/methods , Paresis/complications , Paresis , Paresis , Pleural Effusion/complications , Pleural Effusion/diagnosis , Pleural Effusion/etiology , Carcinoma, Bronchogenic/complications , Carcinoma, Bronchogenic/diagnosis , Carcinoma, Bronchogenic , Lung Neoplasms/complications , Lung Neoplasms/diagnosis , Lung Neoplasms , Prognosis , Tuberculosis, Pulmonary/complications , Tuberculosis, Pulmonary , Tuberculosis, Pulmonary , Biopsy/methodsABSTRACT
Two models are made to account for the dynamics of a consumer-resource system in which the consumers are divided into juveniles and adults. The resource grows logistically and a type II functional response is assumed for consumers. Resource levels determine fecundity and maturation rates in one model, and mortality rates in the other. The analysis of the models shows that the condition for establishment of consumers is that the product of per capita fecundity rate and maturation rates is higher than the product of juvenile and adult per capita decay rates at a resource level equal to its carrying capacity. This result imposes a minimal abundance of resource able to maintain the consumers. A second result shows an equilibrium stage structure, with a small instability when juveniles and adults mean saturation constants are different. The implications of these results for community dynamics are discussed.
Subject(s)
Competitive Behavior , Conservation of Natural Resources , Population Dynamics , Age Factors , Animals , Fertility , Models, Biological , MortalityABSTRACT
Arachnoiditis ossificans (AO) is a rare entity in which ossification of the leptomeninges occurs. This report illustrates a patient with AO of the cervical and dorsal spine, diagnosed by helical computed tomography with multiplanar reconstruction. It demonstrates the value of computed tomography in diagnosing calcified plaques and the utility of multiplanar reconstruction in giving an exact anatomic reference to neurosurgeon.
