Francisco de Leon

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R. R. Miller, W. L. Minckley and S. M. Norris, Freshwater Fishes of México. The University of Chicago Press, Chicago, USA, 2005, 490 pp, $75.00. When I was invited to review ‘‘Freshwater Fishes of México’’, the first thing that came to mind was that there are other, far more experienced ichthyologists who could better appreciate the reach and limitations of(More)
Most eucaryotic organisms classified as living in an extreme habitat are invertebrates. Here we report of a fish living in a Mexican cave (Cueva del Azufre) that is rich in highly toxic H2S. We compared the water chemistry and fish communities of the cave and several nearby surface streams. Our study revealed high concentrations of H2S in the cave and its(More)
The cave molly, Poecilia mexicana, from the Cueva del Azufre, a sulfur cave in Tabasco, Mexico, ranks among the best-studied cave fishes worldwide, despite being known from a single population only. Here we describe a newly discovered second population of cave-dwelling P. mexicana from a nearby, but mostly non-sulfidic cave (Luna Azufre). Despite apparent(More)
Extreme habitats challenge animals with highly adverse conditions, like extreme temperatures or toxic substances. In this paper, we report of a fish (Poecilia mexicana) inhabiting a limestone cave in Mexico. Several springs inside the cave are rich in toxic H2S. We demonstrate that a behavioural adaptation, aquatic surface respiration (ASR), allows for the(More)
While biologists have been aware of theexistence of native Mexican trouts for over acentury, they have received little study. Thefew early studies that did much more thanmention their existence began in the 1930s andcontinued into the early 1960s, focusingprimarily on distributional surveys andtaxonomic analyses. Starting in the 1980s theBaja California(More)
This paper presents a physically consistent dual model applicable to single-phase two-winding transformers for the calculation of low-frequency transients. First, the topology of a dual electrical equivalent circuit is obtained from the direct application of the principle of duality. Then, the model parameters are computed considering the variations of the(More)
The air-core inductance of power transformers is measured using a nonideal low-power rectifier. Its dc output serves to drive the transformer into deep saturation, and its ripple provides low-amplitude variable excitation. The principal advantage of the proposed method is its simplicity. For validation, the experimental results are compared with 3-D(More)
This paper presents a general method for building equivalent electric circuits of power transformers, including eddy current effects in windings and core. A high-frequency equivalent dual model for singleand three-phase transformers with two multilayer windings is derived from the application of the principle of duality. The model is built from elements(More)
We examined the preference of Atlantic molly females (Poecilia mexicana) to associate with a well-fed or a starved male in simultaneous choice tests. Females from three different populations were tested in three treatments: (1) the females could choose on the basis of multiple cues from the males (visual plus non-visual); (2) only non-visual cues could be(More)
The majority of studies on ecological speciation in animals have investigated the divergence caused by biotic factors like divergent food sources or predatory regimes. Here, we examined a system where ecological speciation can clearly be ascribed to abiotic environmental gradients of naturally occurring toxic hydrogen sulfide (H2S). In southern Mexico, two(More)