Genetic capacitors moderate expression of heritable variation and provide a novel mechanism for rapid evolution. The prototypic genetic capacitor, Hsp90, interfaces stress responses, developmental networks, trait thresholds and expression of wide-ranging morphological changes in Drosophila and other organisms. The Hsp90 capacitor hypothesis, that stress-sensitive storage and release of genetic variation through Hsp90 facilitates adaptive evolution in unpredictable environments, has been challenged by the belief that Hsp90-buffered variation is unconditionally deleterious.

This article presents the study of the activity and feeding pattern of a wild group of brown capuchin monkeys (MC-1) in a forest sector of the Tinigua National Natural Park (Meta, Colombia). This group was provisioned daily with a limited amount of food, usually bananas, for scientific purposes for more than 10 years; therefore, enjoying a food resource that did not vary spatially or temporarily. Using scan sampling, 971 hours of troop observation were completed during six months in 1995-96. MC-1 invested 55.2% of their time foraging, followed

Density and population status of red howler monkeys in an isolated bamboo forest fragment in La Tebaida, Quindío, Colombia. The majority of forest remnants in the coffee growing region in Colombia are guaduales, forests with a predominance of thorny bamboos (Guadua spp.). These remnants support the last remaining populations of red howler monkeys found between 800 and 1,300 m of altitude in the Central Cordillera of Colombia. Objective: To assess the population status of howler monkeys in a 51.4 ha-bamboo forest fragment

The montane forests in Colombia have suffered strong degradation due to human activities; currently, most of them are remnants isolated and immersed in anthropogenic habitats. The red howler monkeys have persisted in these conditions but little is known on their biology and response to the alteration of their environment. During five months in 2005, we evaluated the population density and status of this species in the basin of the

Due to human activities, the Colombian Andean forests have lost about 85% of their original cover and very few species of primates persist in these fragmented landscapes. In the Western Cordillera, we evaluated the population density of Alouatta seniculus and Cebus capucinus by line transect census methodology, in a pre-montane isolated forest fragment of 559 ha, between 1200 to 1700 m of altitude. This is one of the few localities where the two species coexist naturally and the first study of their abundance in this cordillera.

As part of a study of responses by red howler monkeys (Alouatta seniculus) to forest fragmentation, we studied red howlers in an extensive forest including a habitat mosaic of old-growth forest, secondary forest of different ages, and non-commercial monospecific plantations of exotic Chinese ash (Fraxinus chinensis) and pines, to produce baseline information on resource use and their role as seed dispersers.

This paper addresses the conservation status of the spectacled bear Tremarctos ornatus in the northern Andes (Venezuela, Colombia and Ecuador) by analysing the degree of range fragmentation and estimating habitat availability. From satellite images we constructed maps of remnant habitat blocks, consisting of Andean forest and páramo (high elevation shrublands and grassland) ecosystems. This information was overlain with a road map to determine potential isolation of populations, and a human accessibility model was used to estimate the core area of each block.

We studied habitat use and ranging patterns of five red howler monkey troops for six months in a lower montane forest in the Colombian Andes. The study area is a mosaic of mature and secondary forest and non-commercial ash, pine and oak plantations that were established as part of a reforestation program. Home ranges (10 ± 3 ha) and daily distances traveled (554 ± 248 m) were similar to those reported for lowland habitats. Home range use differed between groups using mature forest versus secondary forest and plantations, reflecting structural differences between habitat types.

Colonial ascidians are the only chordates to undergo whole body regeneration (WBR), the ability to form an entirely new individual from the peripheral vasculature. Here we describe WBR in Botrylloides violaceus, a colonial ascidian that reliably regenerates after ablation of all zooids and buds of young colonies. During early regeneration several buds develop within the tunic vasculature, but only one continues development into a complete zooid.

The molgulid ascidians are a monophyletic group of tunicates that share specific morphological features, including a heart/kidney complex and hermaphroditic gonads found on both sides of the adult. The larval body plan, however, is quite plastic, with tailless species evolving at least four times independently within the molgulids. The Roscovita clade of molgulid ascidians includes three species that are found sympatrically in Roscoff, France, and includes both tailed and tailless species.