RESUMO
Human-induced disturbances affect animal behaviours such as anti-predatory responses. Animals in urban environments tend to exhibit a reduced escape response, measured as a shorter flight initiation distance (FID), compared to their rural counterparts. While FID has been evaluated in animals dwelling in contrasting habitats (e.g. urban versus rural), little is known about how this response varies within urban environments, especially in tropical cities. Here, we studied the FID of 15 resident bird species in Bogota, Colombia, at 22 sites grouped into four categories (natural sites, metropolitan parks, zonal parks and residential areas) that differed in landscape features and evaluated which factors affected the escape responses of birds. We showed that birds foraging in larger flocks are more tolerant when being approached but they do not seem to be influenced by other factors such as heterospecific flock size, noise levels, pedestrian density, predator density, natural cover or body length. Also, birds inhabiting residential areas and parks showed a shorter FID compared to birds in natural areas suggesting that they are more tolerant of human-related disturbances compared to their conspecifics that live in natural areas within the city. Our study shows important differences in bird anti-predatory responses within the city and suggests that social strategies (i.e. flocking patterns) may be a mechanism for adapting to human-induced disturbances in urban tropical environments.
RESUMO
Genetic structure of a group of capybaras, Hydrochoerus hydrochaeris (Rodentia: Hydrocheridae) in the Colombian Eastern Llanos. The capybaras are the biggest rodents in the world but, however, there are not extensive population genetics studies on them. In the current work, we studied the genetic structure of a troop of 31 capybaras (Hydrochoerus hydrochaeris) sampled in Hato Corozal, Casanare Department at the Colombian Eastern Llanos, by means of five microsatellite markers. The gene diversity was 0.61 and the average allele number was 5.2, which is a medium-low level for markers of this nature. Out five markers employed, three were in Hardy-Weinberg equilibrium meanwhile one showed a significant homozygote excess and other presented a significant heterozygote excess. There were not significant genetic differences between males and females inside this troop. The application of different procedures to determine possible historical demographic changes (population expansions or bottlenecks) clearly showed that the population analyzed crossed over a very narrow recent bottleneck. The illegal hunt is the possibly cause of this strong genetic bottleneck. Rev. Biol. Trop. 59 (4): 1777-1793. Epub 2011 December 01.
Los capibaras son los roedores más grandes del mundo, sin embargo, no se han realizado estudios genético poblacionales exhaustivos con ellos. En el presente trabajo se analizó la estructura genética de una manada de 31 capibaras (Hydrochoerus hydrochaeris) muestreada en Hato Corozal, Departamento de Casanare en los Llanos Orientales de Colombia, mediante cinco marcadores microsatelitales. La diversidad genética se determinó en 0.61 y un número promedio de alelos de 5.2, lo cual se puede considerar medio-bajo para este tipo de marcadores. De los cinco marcadores empleados, tres mostraron proporciones genotípicas en concordancia con lo esperado en equilibrio Hardy-Weinberg, mientras que un marcador mostró un exceso significativo de homocigotos y otro un exceso significativo de heterocigotos. No se encontraron diferencias significativas para esos cinco marcadores entre machos y hembras de la manada muestreada. La aplicación de diferentes procedimientos para detectar posibles cambios demográficos históricos (expansiones poblacionales o cuellos de botella) mostró claramente que la población analizada ha pasado por un cuello de botella extremadamente fuerte en épocas recientes. La limitada variabilidad genética encontrada y la fuerte evidencia de que la manada estudiada ha pasado por un cuello de botella reciente es probablemente el resultado de la cacería ilegal.
Assuntos
Animais , Feminino , Masculino , Genética Populacional , Variação Genética/genética , Repetições de Microssatélites/genética , Roedores/genética , Colômbia , GenótipoRESUMO
The capybaras are the biggest rodents in the world but, however, there are not extensive population genetics studies on them. In the current work, we studied the genetic structure of a troop of 31 capybaras (Hydrochoerus hydrochaeris) sampled in Hato Corozal, Casanare Department at the Colombian Eastern Llanos, by means of five microsatellite markers. The gene diversity was 0.61 and the average allele number was 5.2, which is a medium-low level for markers of this nature. Out five markers employed, three were in Hardy-Weinberg equilibrium meanwhile one showed a significant homozygote excess and other presented a significant heterozygote excess. There were not significant genetic differences between males and females inside this troop. The application of different procedures to determine possible historical demographic changes (population expansions or bottlenecks) clearly showed that the population analyzed crossed over a very narrow recent bottleneck. The illegal hunt is the possibly cause of this strong genetic bottleneck.