The preferred temperature (PT) of Poecilia sphenops (Pisces, Poeciliidae) (n = 240, 1.13 +/- 0.06 g wet weight, 3.26 +/- 0.88 cm standard length) from Presa Piedra Azul, Oaxaca, Mexico, was measured at acclimation temperature of 20 degreesC, 23 degreesC,…

While biologists have been aware of the existence of native Mexican trouts for over a century, they have received little study. The few early studies that did muchmore than mention their existence began in the 1930s and continued into the…

La evolución de las características ecológicas de las especies es uno de los temas más intensamente estudiados, pero su complejidad suele limitar estos estudios a evidencias indirectas de las adaptaciones reales de los organismos. Recientemente, métodos moleculares como los "micro-arrays"…

While birdsong is a model system for animal communication studies, our knowledge is derived primarily from the study of only one sex and is therefore incomplete. The study of song in a role-reversed species would provide a unique opportunity to…

For the first time for Mexican mycobiota the genus Cerinomyces Mar. is reported with the species C lagerheimii (Pat.) McNabb. This species only have been found in Ecuador (type locality), Brasil, United States and Venezuela. A review of different specimens…

In 1950, Tinbergen described the elicitation of offspring begging by the red spot on the bill of parent gulls, and this became a model system for behavioural studies. Current knowledge on colour traits suggests they can act as sexual signals…

Studies of tropical secondary forest succession face strong limitations due to the slow pace of succession and the time-consuming task of monitoring processes. The occurrence of tree rings in secondary forest trees may help expand our knowledge on succession in…

The region of Huatusco, in Veracruz, Mexico, is an area of high coffee production. Coffee trees are sensitive to temperature and precipitation variations. Those climatic elements are related to the altitude, aspect and slope it? the agroecological shadow system. A…

Volcan de Colima has increased its activity considerably since 1998 with four periods of effusion and since 2003, daily Vulcanian explosions. During 2005 the magnitude of the explosivity increased, producing many pyroclastic flows, two of which reached over 5 km…

Most neural network learning algorithms cannot use knowledge other than what is provided in the training data. Initialized using random weights, they cannot use prior knowledge such as knowledge stored in previously trained networks. This manuscript thesis addresses this problem.…