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espanolFrente al cambio ambiental inducido por el hombre, se requieren datos biologicos basicos para las especies amenazadas por los impactos de las actividades humanas para disenar y ejecutar estrategias adecuadas de conservacion. Aqui reportamos datos basicos de algunos aspectos de la historia de vida de 2 poblaciones del topote del Tamesi Poecilia latipunctata (Poeciliidae), nativa de los manantiales del rio Tamesi en el noreste de Mexico y catalogada en peligro critico. Ademas, comparamos su historia de vida con la de 2 especies sintopicas, el topote del Atlantico (Poecilia mexicana) y el topote del Amazonas (Poecilia formosa). Las historias de vida de P. latipunctata son, en gran parte, similares a las de otros topotes: el tamano del macho se distribuyo normalmente en ambas poblaciones y las hembras produjeron huevos de forma discreta, predominantemente con vitelo para el aprovisionamiento de embriones. Sin embargo, en nuestros 2 sitios de muestreo, los machos de P. latipunctata fueron mas pequenos que los machos de P. mexicana y las hembras de P. latipunctata produjeron crias significativamente mas grandes que P. formosa o P. mexicana. Basandonos en los patrones de tamano de los machos y de los descendientes, sugerimos que, ademas de la perturbacion antropogenica, P. latipunctata tambien este sufriendo una fuerte competencia interespecifica, por lo que recomendamos mas investigaciones sobre la biologia basica de esta especie (incluida su capacidad competitiva). EnglishIn the face of human-induced environmental change, basic biological data for species threatened by the impacts of human activities are sorely needed to devise and execute proper conservation strategies. Here we provide aspects of basic life-history data for 2 populations of the critically endangered Tamesi molly Poecilia latipunctata (Poeciliidae), which is native to the headwaters of the Rio Tamesi in northeastern Mexico. Furthermore, we compare their life history to that of 2 syntopic species, the Atlantic molly (Poecilia mexicana) and the Amazon molly (Poecilia formosa). Life histories of P. latipunctata are largely similar to that of other mollies: male size was normally distributed in both populations, and females produced 1 clutch at a time, while relying predominantly on yolk for embryo provisioning. However, at our 2 sample sites, P. latipunctata males were smaller than P. mexicana males, and P. latipunctata females produced significantly larger offspring than either P. formosa or P. mexicana. Based on patterns of male and offspring size, we cautiously suggest that, besides anthropogenic disturbance, P. latipunctata might also be suffering from strong interspecific competition, and we call on more research into the basic biology of this species (including its competitive ability).

Pre-existing female biases are female preferences for a particular trait that evolved prior to the evolution of that trait. Phylogenies are needed to show when the preference and trait have originated. In several live-bearing fishes (Poeciliidae), females show pre-existing biases for male swords, a colorful extension of the caudal fin. Here, we investigated the pre-existing bias hypothesis by predicting preferences for a sword in several molly species, including 2 unusual species in the monophyletic subclade Mollienesia: the Amazon molly, Poecilia formosa, a sperm-dependent hybrid form, and the Tamesi molly, Poecilia latipunctata, a species in the long-fin molly clade, that has a short-fin morphology. Using published sequence data available for this family, behavioral approaches, robust phylogenetic analyses, and Bayesian ancestral state reconstructions, we tested whether the hybrid P. formosa has a preference similar to the maternal ancestor, Poecilia mexicana, or the paternal ancestor, Poecilia latipinna. Surprisingly, the preference shown by P. formosa was variable between populations and matched the preference found in the co-occurring host species. In P. latipunctata, we found a pre-existing bias for sworded males, suggesting that this represents an ancestral trait for the long-fin molly clade. On the basis of the combined evidence from multiple studies, it seems as if pre-existing biases for sworded males are relatively basal to poeciliids and that existing phylogenetic relationships allow us to predict sensory biases.

Common names: Tamesi molly (US), Topote del Tamesi (MX). Conservation status: Listed as ‘critically endangered’ by the IUCN based on population declines, fragmentation of populations, and decline of habitat quality. The species is federally protected by the Mexican government (SEDESOL 1994). Identification: Poecilia latipunctata is a typical molly characterized by a longitudinal stripe of discontinuous black spots midside of body. The maximum size is ~50 mm. Illustration by Debby Kaspari. Distribution: Confined to the headwaters of the Rio Tamesi (Rios Guayalejo and Mante), Tamaulipas, Mexico. It was introduced into La Media Luna, San Luis Potosi (Miller et al. 2005). Ecology: This species prefers gravelly to muddy habitats with clear, flowing water and aquatic vegetation. It also occurs in irrigation ditches with lower flow and overhanging vegetation. Poecilia latipunctata predominantly feeds on detritus and algae (Darnell 1962). It occurs sympatrically with two other molly species, P. mexicana and P. formosa, and has been documented to serve as sperm donor for gynogenetic P. formosa females (Niemeitz et al. 2002). Although phenotypically a short-fin molly, the species is closely related to the long fin clade within the mollies (Ptacek et al. 2005). Threats: The species is threatened predominantly through fragmentation of suitable habitats as well as habitat deterioration by intense agriculture and invasive species. Conservation recommendations: The species is protected by Mexican law, but no specific conservation actions have been taken to date. The current distribution and abundance of P. latipunctata should be Environ Biol Fish (2009) 85:31–32 DOI 10.1007/s10641-009-9451-1