Crater lake cichlids individually specialize along the benthic-limnetic axis

A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of elongated open water (limnetic) species and high-bodied shore (benthic) species from generalist ancestors. Studies on phenotype-diet correlations have suggested that population-wide individual specialization occurs at an early evolutionary and ecological stage of divergence and niche partitioning. This variable restricted niche use across individuals can provide the raw material for earliest stages of sympatric divergence. We investigated variation in morphology and diet as well as their correlations along the benthic-limnetic axis in an extremely young Midas cichlid species, Amphilophus tolteca, endemic to the Nicaraguan crater lake Asososca Managua. We found that A. tolteca varied continuously in ecologically relevant traits such as body shape and lower pharyngeal jaw morphology. The correlation of these phenotypes with niche suggested that individuals are specialized along the benthic-limnetic axis. No genetic differentiation within the crater lake was detected based on genotypes from 13 microsatellite loci. Overall, we found that individual specialization in this young crater lake species encompasses the limnetic- as well as the benthic macro-habitat. Yet there is no evidence for any diversification within the species, making this a candidate system for studying what might be the early stages preceding sympatric divergence

Communication : where evolutionary linguistics went wrong

In this article we offer a detailed assessment of current approaches to the origins of language, with a special focus on their historical and theoretical underpinnings. It is a widely accepted view within evolutionary linguistics that an account of the emergence of human language necessarily involves paying special attention to its communicative function and its relation to other animal communication systems. Ever since Darwin, some variant of this view has constituted the mainstream version in evolutionary linguistics; however, it is our contention in this article that this approach is seriously flawed, and that "animal communication" does not constitute a natural kind on which a sound theoretical model can be built. As a consequence, we argue that this communicative perspective is better abandoned in favor of a structural/formal approach based on the notion of homology, and that some interesting and unexpected similarities may be found by applying this venerable comparative method founded in the 19th century by Richard Owen

Cyrtocara liemi, a previously undescribed paedophagous cichlid fish (Teleostei: Cichlidae) from Lake Malawi, Africa

Volume: 95Start Page: 398End Page: 40

El comportamiento y la reproducción del guapote lagunero (Cichlasoma dovil : Gunther 1869)

La anidación de Cichlasoma Dovi en la laguna de Xiloá, Nicaragua, fue estudiada a través de la observación directa y usando la técnica de buceo. La especie de estudio anidó entre noviembre y mayo, a profundidades de 7 y hasta 21 metros. La tasa de éxito en el reclutamiento de alevines fue mayor para anidaciones en diciembre. El comportamiento del macho en apareamiento es facultativo: algunos abandonaron el nido al nacer los alevines, otros mantuvieron presencia en o alrededor del nido hasta el reclutamiento de los alevines o hasta el fracaso del nido por depredación. Se observó el comportamiento de seis machos con una sola hembra y de seis machos con dos y hasta cinco hembras cada uno, en anidación simultánea. Se liberaron 198 +/- 117 alevines por nido, entre edades de 60 +/- 7 días en 28 nidos estudiados de 45 estudiados en situaciones en que no hubo participación del macho. La hembra defiende el nido principalmente contra tres especies: Neetroplus nematopus, Cichlasoma citrinellum, y Gobiomorus dormitor, este último con frecuencia invade exitosamente el nido

Zoogeografía íctica de lagunas cratéricas de Nicaragua

En ocho lagunas cratéricas volcánicas de Nicaragua se observan 20 nuevos records distribucionales de especies de peces. Estas lagunas, de origen relativamente reciente, son dominadas por peces secundarios de agua dulce, especialmente de las familias Cichlidae y Poeciliidae. Se considera que el origen de los peces proviene de poblaciones de los más viejos y Grandes Lagos de Nicaragua. En las lagunas se encontró entre 3 a 16 especies ícticas. Esta riqueza íctica se correlaciona con un orden modificado de las edades de las lagunas (P—O.OI 1) y con un orden modificado del área de superficie (P—O.OI 3)