Evolución y Diversidad: Los Grandes Especiadores

lunes, 2 de febrero de 2009

Los Grandes Especiadores

Con una tasa de diversificación aproximada de 0.5 especies por millón de años, yo pensaba que los Scytalopus (Rhinocryptidae) que hemos estado estudiando hace tiempo eran un caso excepcional de diversificación rápida a escala continental entre las aves. Comparados con los "grandes especiadores" del género Zosterops de los que habló Jared Diamond desde la década de 1970 y que ahora son objeto de un estudio reciente de Rob Moyle et al. publicado online hace un par de días en PNAS, los Scytalopus no parecen muy especiales que digamos... El artículo de Moyle y colaboradores ya ha sido comentado en detalle en otro blog así que no comentaré mucho sobre los detalles de sus muy interesantes resultados (i.e. 1.95—2.63 especies por millón de años!). Lo que sí llama la atención es que la propensión a presentar evolución morfológica rápida que estas aves tendrían como lo sugieren los autores, es consistente con los resultados de la tesis de Andrea Baquero, una de mis estudiantes de pregrado, en su estudio sobre cambios morfológicos y de vocalizaciones en Zosterops (Speirops) lugubris como resultado de su presencia en plantaciones de café y cacao en la Isla de Săo Tomé (sí, Săo Tomé).

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"Biodiversity is thus signally valuable because of its intellectual interest. A proactive role in its conservation is required because it is irreplaceable - extinctions are forever. Arguments from intellectual interest may seem unconvincing to those who demand immediate pragmatic virtues in the narrowest sense of immediate utility. This attitude is typical in the United States, where, for instance, the accepted legal defense of a controversial sexually explicit work of art is to claim that it has redeeming social value, not that it is, after all, a work of art. Nevertheless, the best argument for the conservation of biodiversity remains its intellectual promise. Narrow pragmatism would lead to a devaluation not just of biodiversity but of the entire scientific enterprise, if not of every intellectual and aesthetic aspect of human culture. We should not be embarrased to defend the importance of our intellectual interests and pursuits. All the comforts of life that are traded in the marketplace are ultimately the products of human intellectual life, of our culture, and very often -but obviously not always- of that part of our intellectual culture that we identify as science. Thus even narrow pragmatism dictates the attribution of a high value to intellectual life and science; without them, pragmatism would be useless. Janzen was correct to note that biologists have a professional imperative to conserve biodiversity. Nonbiologists share that imperative to the extent that they value biology as a field of endeavor that should be pursued in any society that can afford it. Moreover, there is nothing that says that nonbiologists cannot share the pleasure of the knowledge that the professional pursuit of biology generates. The world is interesting. We enjoy knowing about it, though some of us may cherish this knowledge more than others. Finally, for many individuals, not limited to professional scientists, scientific knowledge of the world, the sense that we are beginning to understand our surroundings, deeply affects our most basic attitudes towards all aspects of life. Science has a cultural value beyond the technology that it provides."

Sarkar, S. 2005. Biodiversity and environmental philosophy, an introduction. Cambridge University Press.