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,…

Diabetes mellitus is a syndrome which affects more and more people in all countries over the world. In Mexico, it is commonly treated with herbal extracts. Such treatment may be of considerable benefit especially during the early stages of the…

Although our biological knowledge regarding cactus species is thorough in many areas, only in recent years have ecologists addressed their demographic behavior. Here we attempt a first review of the present knowledge on cactus demography, including an analysis of the…

Species of Philophthalmus parasitize primarily the eyes of wild and domestic birds. A variety of mammals, including humans, occasionally serve as the intermediate as well as the definitive hosts for this parasite, although human cases are extremely rare. Here, we…

Early in the twentieth century it was shown that Mendel's laws apply to plants and animals and that genes reside on chromosomes. In the 1950s the double-helix model of DNA inaugurated the molecular biology era, which culminated at the end…

A new terrestrial species of Pseudoeurycea is described from the mountains of the Mixteca region of Oaxaca. Compared with other members of the genus, the new species is relatively slender and short-legged. The background color of the dorsum of this…

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…

A new tertiary stibine and bismuthine containing C-heterocyclic selenophene ring have been synthesized. Tris(2-selenophenyl)stibine (1) and tris(2-selenophenyl) bismuthine (2) and characterized by IR, MS, H-1, C-13, COSY, HETCOR NMR spectroscopy. Crystal structures of stibine and bismuthine have been determined. In…

In various species of crayfish it has been proposed that different extra-retinal photoreceptors and pacemakers could be involved in the photo entrainment mechanisms. The identity of the neural structures responsible for this phenomenon is not known. The objective of this…

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…