The Role of Habitat Heterogeneity in Structuring Mangrove Bird Assemblages

Mangrove habitats are under severe land use pressure throughout the world and Australia is no exception. Here we describe the heterogeneity of mangrove habitat and its relationship with mangrove bird diversity. We examined the role of mangrove habitat complexity in determining the richness of avian mangrove dependent species (MDS) and interior species, overall bird species richness and density. High species richness (overall and MDS) and density in the mangroves was associated with plant species richness, the density of the understory and food resource distribution. Furthermore, habitat heterogeneity rather than patch area per se was a more important predictor of species richness in the mangroves. These findings stress the importance of habitat diversity and quality to the diversity and density of birds in mangroves. Thus, habitat heterogeneity within mangroves is a crucial patch characteristic, independent of mangrove patch size, for maintaining diverse avian species assemblages

Resource Partitioning by Mangrove Bird Communities in North Australia

Mangrove bird communities in north Australia comprise relatively few passerine species compared with other arboreal habitats in the region. Mangroves are dominated by a few tree species and there are potentially few resource axes available for partitioning by terrestrial birds. Competition for limited resources is predicted to cause strong niche differentiation and a highly structured, but low diversity, bird assemblage. Using multivariate and bipartite network analyses based on 1771 foraging observations (33% of 5320 behavioral observations), we examined resource partitioning by 20 terrestrial bird species in mangroves of north Australia. The mangrove bird community largely comprised generalist insectivores that partitioned insects by size with moderate-to-high interspecific overlap in diet. Gleaning for insects was the most common foraging mode. Few species specialized on nectar. Flowers of one or more mangrove species were available in every month of the year and insect abundance was correlated with flowering peaks. Niche differentiation by birds was determined by food type and foraging mode more than by broad spatial (mangrove zones) or temporal (seasonal) segregation of the use of resources. There was little evidence of bird species saturation or species sorting, suggesting loose species packing and a lesser role than expected for species interactions and interference competition in structuring the bird assemblage in mangroves

Avian species-assemblage structure and indicator bird species of mangroves in the Australian monsoon tropics

Mangroves are threatened worldwide yet they host diverse avian assemblages, especially in Australia. We examined the diversity, density and habitat use of birds in northern Australian mangroves to determine the influence of habitat patch-size and floristic composition on the structure of mangrove bird assemblages. Birds were surveyed using line transects in 13 mangrove patches. A total of 70 species was encountered, with a mean density of 11.7 individuals ha–1,including 11 of 12 known mangrove-dependent species. Many species were strongly associated with, and indicative of, a specific mangrove plant zone, emphasising the importance of the number of zones to bird diversity at a site. Of six functional guilds, the insectivores were most dominant, followed by nectarivores. Accordingly, avian assemblage structure was influenced by mangrove flowering phenology. Large mangrove patches supported fewer species than many smaller patches of equivalent combined area, and species richness was independent of area. In addition, there was no density compensation or a density–area relationship, implying that assemblages are not saturated with species and species interactions do not determine assemblage structure. In order of increasing importance, avian assemblage structure in mangroves is determined by the type and diversity of mangrove zones, the timing of mangrove flowering and the nature of the matrix surrounding mangroves

Mature astrocytes in the adult human neocortex express the early neuronal marker doublecortin.

Doublecortin (DCX) is a microtubule-associated protein expressed by migrating neuroblasts and is considered to be a reliable marker of neurogenesis. DCX has been used to study the relation between neurogenesis in adult human brain and neurological and neurodegenerative disease processes in the search for putative therapeutic strategies. Using autopsy and surgically resected tissue from a total of 60 patients, we present evidence that DCX is present in several cellular compartments of differentiated astrocytes in the adult human neocortex. One of these compartments consisted of peripheral processes forming punctate envelopes around mature neuronal cell bodies. Markers of glial activation, such as GFAP and HLA, were not associated with DCX immunoreactivity, however, the presence of cytoarchitectural alterations tended to correlate with reduced DCX staining of astrocytic somata. Interestingly, local Alzheimer pathology that showed no relation with cytoarchitectural abnormalities appeared to correlate negatively with the expression of DCX in the astrocytic somata. In combination with the literature our data support the view that DCX in the adult human neocortex may have a function in glia-to-neuron communication. Furthermore, our result

Prognostic Significance of POLE Proofreading Mutations in Endometrial Cancer

Biological, physical and clinical aspects of cancer treatment with ionising radiatio