Endless forms most hidden: katydids that masquerade as moss

In the cloud forests of the central range of the Colombian Andes, we discovered a species of katydid (Orthoptera: Tettigoniidae) that imitates mosses to an uncanny degree and is exceedingly difficult to detect. The camouflage exhibited by this particular katydid seems quite specific. We discuss the evolutionary consequences of this sort of specialization. Selection to maintain effective disguises can result in reproductive isolation between populations specialized for different microhabitats, which makes it reasonable to speculate that camouflage may increasing diversification rates. Camouflage could also come at the price of elevated extinction risk. This possibility must be considered because although antipredator defenses are often thought of as leading to “escape-and-radiate” dynamics where diversification follows innovation that allows expansion into new niches, recent work has shown unexpected extinction risk associated with some antipredator adaptations. Highly specialized camouflage would seem an ambiguous case because of its obvious benefits, but also potential costs such as inhabiting habitats with low carrying capacities, vulnerability to predators at high densities if predators form search images, or metabolic trade-offs with thermoregulation. Groups such as the Tettigoniidae provide a tantalizing opportunity for their exceptional diversity, wide geographic distribution, and striking array of disguises suggest that many independent evolutionary experiments have already taken place

Estructura interna del área de distribución geográfica: el caso de la Guagua loba (Dinomys branickii Peters 1843)

En este trabajo se hace una propuesta de generador de transformaciones gauge locales en teorías topológicas del tipo Chern- Simons, diferente al reportado en la literatura, que reproduce los resultados estándar. Las ventajas de este generador son: Para transformaciones gauge usuales es diferenciable funcionalmente sin adicionar condiciones de frontera y sobre el espacio físico este generador satisface un algebra de Kac-Moody, que vía construcción de Sugawara, es un algebra de Virasoro. Para transformaciones gauge generalizadas es funcionalmente diferenciable después de adicionar condiciones de frontera y sobre el espacio físico, este generador constituye una algebra de Virasoro. Posteriormente se realiza la formulación de primer orden de gravedad en (2+l)-dimensiones y se obtiene que gravedad en (2+1) esta descrita por una suma directa de dos teorías de Chern-Simons D=3 y por lo tanto, la carga central para transformaciones gauge generalizadas (relacionada a los difeomorfísmos) se puede emplear en la fórmula de Cardy de CFT unitarias, para producir la entropía de Hawking-Bekestein de un agujero negro BTZ

Mating behavior in two sympatric species of andean tiger beetles (Cicindelidae)

The tiger beetle genus Pseudoxycheila (Cicindelidae) currently contains 21 species, distributed in mid and high elevations in the Andes from Bolivia to Venezuela and in mountains in Panama and Costa Rica. The center of origin of the genus is in the Andes of Colombia and Ecuador. In this study we describe the mating behavior of two species, P. chaudoiri and P. confusa, that co-occur at an elevation of 1900 m on the western Andean range of Colombia (3° 30' N 76° 34' W). The two species used similar habitats, which are inclined surfaces with bare, clay soils, but were spatially segregated by microclimatic differences. The mating behavior of both species was similar. It was characterized by haphazard encounters of males and females at oviposition sites, and males attempting to mount females. When females were not laying, mounting was followed by a precopulatory struggle (female attempting to dislodge male), copulation, a postcopulatory association (PCA), a postcopulatory struggle, and finally dislodging of the male by the female. About half of the mating attempts occurred with females that were starting to lay eggs; in theses cases usually there was no Boletín del Museo de Entomología de la Universidad del Valle 9(1): 22-28, 2008 23 precopulatory struggle and after copulation the female usually continued egg laying with the male in amplexus. PCA likely represented mate-guarding behavior, but males in PCA were dislodged by intruding males. In some cases, however, males in PCA were probably able to fertilize several eggs that were laid in sequence. The mating behavior of these two species is possibly a result of a sexual conflict of interests, in which males try to mate with any female they encounter and females resist, but only to the point at which struggling and interrupting egg-laying is more costly than accepting copulation

Bajando la escala en las redes de interacción planta-frugívoro para un ensamblaje de consumidores de ficus

Measuring interaction strength is key to understand the dynamics of mutualistic networks. However, how intraspecific variation within species traits can affect the patterns and outcomes of an interaction has been poorly measured. In this study, we explored how individual variation in fruit production in a fig tree species influences fruit consumption by frugivorous birds. Degree, expressed as the number of bird species, and visitation rates, expressed as number of individuals and its equivalent biomass, were independent of crop size. However, the cumulative number of visits for the three variables mentioned above was proportional to crop size. The number of small bird species (<100 g) was twice that from large species. However, the biomass of both groups was equivalent. Fruit consumption, expressed both as intake rate and total intake, was proportional to bird body mass. Our results suggest that the interaction between birds and fig trees depends on the size distribution of both organisms and the forest successional stage. In addition, from the consumers’ perspective, the amount of energy that each bird obtains depends on individual tree characteristics.Medir la fuerza de la interacción es clave para comprender la dinámica de las redes mutualistas. Sin embargo, la variación intraespecífica en los rasgos de las especies puede afectar los patrones y resultados de las interacciones a una escala aún no medida. En este estudio, exploramos cómo la variación individual en la producción de frutos en una especie de Ficus modula el consumo de frutos por aves. El grado, expresado como número de especies, y las tasas de visitas, expresadas como número individuos y su equivalente en biomasa, fueron independientes del tamaño de la cosecha. Sin embargo, el número acumulado para las tres variables fue proporcional al tamaño de la cosecha. El número de especies de aves pequeñas (<100 g) fue el doble que el de las especies grandes. Sin embargo, la biomasa de ambos grupos fue equivalente. El consumo, expresado tanto en tasa como en ingesta total, fue proporcional al tamaño corporal de las aves. Estos resultados sugieren que la interacción entre aves y Ficus depende de la distribución del tamaño de ambos organismos. Además, desde la perspectiva de los consumidores, la cantidad de energía que obtiene cada ave depende de las características individuales del árbol

Huevos albinos en una población tropical de <i>Troglodytes aedon</i>

In this note, I report on the occurrence of albinistic eggs (i. e., lacking shell pigmentation) in a population of House Wrens (<i>Troglodytes aedon</i>) in Colombia. In a study site encompassing about 15 wren territories, two females laid albinistic eggs during a two-and-a-half year periodo One female laid 17 completely white eggs during the study. The second case involved a progretive 1088 of eggshell pigmentation. This female laid normally pigmented eggs at the beginning of the study, but her eggshells became progressively albinistic, and the end of the study she was laying completely white eggs