ABSTRACT
ResumenLos afloramientos rocosos aislados se describen como paisajes destacados en biodiversidad debido a la gran variedad de microhabitats, presencia de taxones restringidos y al alto recambio de especies con la matriz circundante. Particularmente los afloramientos rocosos aislados del Paraje Tres Cerros (ARPTC), Corrientes, Argentina, representan un paisaje único en la región, biológicamente fueron poco explorados. Se estudió la comunidad de aves de bosques y pastizales de los ARPTC mediante 136 listas de Mackinnon de diez especies durante la temporada reproductiva y no reproductiva. Se evaluó la diversidad, riqueza estimada y completitud de inventarios, abundancia de gremios tróficos y fenología de las especies. Se comparó estos atributos entre los bosques y pastizales. Se registraron 107 especies donde el bosque es 1.3 veces más diverso que el pastizal. La completitud de inventarios varió de 83 a 90 % en el pastizal y de 88 a 99 % en el bosque. Los hábitats se complementaron en un 62 % indicando una elevada ocurrencia de especies exclusivas. Las aves insectívoras fueron abundantes en ambos ambientes, mientras que las frugívoras en bosques y las granívoras en pastizales. Ambos hábitats son significativamente más ricos en especies en la estación reproductiva por la llegada de los migrantes estivales. Los resultados concuerdan con los patrones generales conocidos para las comunidades de aves y con otros específicos para las comunidades de aves de afloramientos rocosos. El presente estudio resalta la importancia de los afloramientos rocosos aislados de Paraje Tres Cerros para la protección de la biodiversidad de aves a nivel local y regional y representa una herramienta de manejo para la conservación de estos ecosistemas.
AbstractIsolated rocky outcrops can act as patch habitats that host great biodiversity through the diversity of microhabitats, presence of restricted taxa and the high turnover of species in the patch matrix. The isolated rocky outcrops of Paraje Tres Cerros (ARPTC), Corrientes, Argentina, are a unique landscape in the region and biologically little explored. We conducted a study to describe for the first time the bird community of the forest and grassland of the ARPTC, using 136 lists following the ten species Mackinnon method from the breeding and non-breeding seasons. We evaluated the diversity, trophic guilds and phenology of the species, and compared attributes of grassland and forest communities. The total species richness was 107, with the forest being 1.3 times more diverse than the grassland. Completeness of inventories ranged from 83-90 % in the grassland and 88 to 99 % in the forest. The habitat complementarity was 62 %, indicating the presence of several species exclusive of forest and grassland habitats. The trophic structure of communities showed a good representation of insectivorous birds in both habitats. Frugivorous birds were more frequent in the forest and granivorous birds were more frequent in the grasslands. Due to the arrival of migrant species, both habitats had significantly higher richness in the breeding season than in the non-breeding season. Our results showed similar general aspects and patterns for bird communities and with specific studies for bird communities of rocky outcrops. The present study highlights the importance of the isolated rocky outcrops of Paraje Tres Cerros for the protection of local and regional bird biodiversity and represents a benchmark for the management and the protection of these ecosystems.
ABSTRACT
In this work we analyzed the karyotype of five populations of Adenomera diptyx from Argentina after conventional staining, Ag-NOR and C-banding. All specimens presented 2n = 26 and FN = 34. The karyotype was formed by three submetacentric, one metacentric and nine telocentric pairs. Silver staining revealed that the NOR was located on a secondary constriction in pair 7. C- banding evidenced constitutive heterochromatin at the pericentromeric region of all chromosomes. The karyotype of A. diptyx was similar to that of A. hylaedactyla (2n = 26, FN = 34) and different from that of A. andreae (2n = 26, FN = 40) in the fundamental number and secondary constriction position. It also differed from the karyotypes of A. marmorata (2n = 24, FN = 34 and 36) and of A. aff. bokermanni (2n = 23, FN = 34) in diploid number. Until a comprehensive cytogenetic analysis of all the species of the genus is performed, their chromosome evolution will remain poorly understood.