The existence of latitudinal gradients in species richness and their abundance is known for many free living organisms but few cases have been reported for parasitic diseases. In addition, asymmetries between the Northern and Southern Hemispheres in several characteristics may affect the distribution and diversity of species at all ecological levels. In this respect, we study the distribution of several genera of blood parasites infecting birds along a latitudinal gradient that includes the world's southernmost forests ecosystems. Birds were mist-netted and sampled for blood in localities across Chile ranging from 33 degrees S to 55 degrees S during the years 2003-06. Overall, 26 bird species were sampled and 27 parasite lineages were identified. The latter belonged to three genera: Plasmodium (8), Haemoproteus (8) and Leucocytozoon (11). We found a positive significant relationship between prevalence and latitude for Leucocytozoon lineages and a negative relationship for Haemoproteus, Plasmodium and mixed infections. However, we did not find a significant relationship between parasite diversity and latitude. We found 18 lineages infecting only one species of host, and 19 lineages appear in only one of the localities of sampling. This pattern implies that some parasite lineages may evolve in isolation in some species/localities. In addition, specificity at the host-family level was only found for Haemoproteus lineages infecting birds in the family Emberizidae. Individuals of the long distance migrant bird white-crested elaenia (Elaenia albiceps), were found infected by the same parasite lineages in localities separated by 20 degrees of latitude. Infections by these lineages were detected in other sedentary birds including juveniles and nestlings of different bird species. Therefore, long distance migrants are able to distort the presence of latitudinal gradients of diseases due to the potential role of migrants in spreading infections. Geographical gradients in prevalence of avian haematozoa differ between parasite genera and hemispheres, probably in relation to the existence of appropriate vector-parasite-host interactions

Impacts of habitat fragmentation on forest bird communities have often been studied in landscapes dominated by agriculture. The striking structural differences between forest fragments and the matrix have led most researchers to rely on island biogeographic theory to predict the distribution of bird species in fragmented forests. However, in some cases the vegetation surrounding fragments is not completely unsuitable for forest birds. Thus, a more general framework is needed to understand the effects of habitat fragmentation. The mosaic approach considers fragments as integrated parts of a complex landscape composed of patches of habitat of different qualities. In the coastal area of the Maule region in central Chile the remaining hualo (Nothofagus glauca) forests cover <10% of the landscape, are severely fragmented, and are imbedded in a matrix of exotic pine plantations. We compared the island and mosaic approaches as explanations for the distribution and abundance of forest birds. Variable circular plots were used to study the distribution of diurnal forest birds in hualo forest fragments and in the surrounding pine plantations. There was a negative relationship between the size of forest fragment and bird species richness per unit area. Fragmentation effects were mostly species‐specific. A few large‐sized bird species tended to be absent from the smaller fragments, while the presence or abundance of most birds showed no relationship with fragment size. The type of vegetation adjacent to forest fragments had a significant effect on the composition of the bird community inhabiting them. The abundance of most cavity‐nesting species in pine plantations was related positively to the proximity of either the nearest native forest fragment or the nearest creek. On the other hand, the frequency of most open‐nesting species in pine plantations was spatially unrelated to either forest fragments or creeks and depended mostly on the characteristics of the vegetation in the understory. Results support the use of the mosaic approach for the study of fragmentation on birds in forest‐dominated landscapes.

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Habitat fragmentation modifies ecological patterns and processes through changes in species richness and abundance. In the coastal Maulino forest, central Chile, both species richness and abundance of insectivorous birds increases in forest fragments compared to continuous forest. Through a field experiment, we examined larvae predation in fragmented forests. Higher richness and abundance of birds foraging at forest fragments translated into more insect larvae preyed upon in forest fragments than in continuous forest. The assessed level of insectivory in forest fragments agrees with lower herbivory levels in forest fragments. This pattern strongly suggests the strengthening of food interactions web in forest fragments of coastal Maulino forest.

Niche description and differentiation at broad geographic scales have been recent major topics in ecology and evolution. Describing the environmental niche structure of sister taxa with known evolutionary trajectories stands out as a useful exercise in understanding niche requirements. Here we model the environmental niche structure and distribution of the recently resolved phylogeography of guanaco (Lama guanicoe) lineages on the western slope of the southern Andes. Using a maximum entropy framework, field data, and information on climate, topography, human density, and vegetation cover, we identify differences between the two subspecies (L.g.cacsilensis, L.g.guanicoe) and their intermediate-hybrid lineage, that most likely determine the distribution of this species. While aridity seems to be a major factor influencing the distribution at the species-level (annual precipitation <900 mm), we also document important differences in niche specificity for each subspecies, where distribution of Northern lineage is explained mainly by elevation (mean = 3,413 m) and precipitation seasonality (mean = 161 mm), hybrid lineage by annual precipitation (mean = 139 mm), and Southern subspecies by annual precipitation (mean = 553 mm), precipitation seasonality (mean = 21 mm) and grass cover (mean = 8.2%). Among lineages, we detected low levels of niche overlap: I (Similarity Index) = 0.06 and D (Schoener’s Similarity Index) = 0.01; and higher levels when comparing Northern and Southern subspecies with hybrids lineage (I = 0.32-0.10 and D = 0.12-0.03, respectively). This suggests that important ecological and/or evolutionary processes are shaping the niche of guanacos in Chile, producing discrepancies when comparing range distribution at the species-level (81,756 km2) with lineages-level (65,321 km2). The subspecies-specific description of niche structure is provided here based upon detailed spatial distribution of the lineages of guanacos in Chile. Such description provides a scientific tool to further develop large scale plans for habitat conservation and preservation of intraspecific genetic variability for this far ranging South American camelid, which inhabits a diversity of ecoregion types from Andean puna to subpolar forests.

The establishment of biological corridors between two otherwise isolated habitat patches is a common yet contentious strategy for conserving populations in fragmented landscapes. We compared the effectiveness of corridors with the effectiveness of an alternate conservation strategy, the enlargement of existing habitat patches. We used a spatially explicit population model that simulated population size in two kinds of patches. One patch had a corridor that connected it to a larger "source" patch and the other patch was unconnected and enlarged at the periphery by an area the same size as the corridor. Patch isolation, corridor width, patch size, and the probability that individuals would cross the border from habitat to matrix were varied independently. In general, population size was greater in enlarged patches than in connected patches when patches were relatively large and isolated. Corridor width and the probability of crossing the border from habitat to matrix did not affect the relative benefit of corridors versus patch enlargement. Although biological corridors may mitigate potential effects of inbreeding depression at long time scales, our results suggest that they are not always the best method of conserving fragmented populations.

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The Convention on Biological Diversity (CBD) expects forestry plantations to contribute to biodiversity conservation. A well-developed understory in forestry plantations might serve as a surrogate habitat for native species and mitigate the negative effect of plantations on species richness. We experimentally tested this hypothesis by removing the understory in Monterey pine (Pinus radiata) plantations in central Chile and assessing changes in species richness and abundance of medium-sized mammals. Frequency of occurrence of mammals, including kodkods (Leopardus guigna), culpeo foxes (Pseudalopex culpaeus), lesser grisons (Conepatus chinga), and Southern pudu deer (Pudu puda), was low in forest stands with little to no understory relative to stands with well-developed undergrowth vegetation. After removing the understory, their frequency of occurrence decreased significantly, whereas in control stands, where understory was not removed, their frequency did not change. This result strongly supports the idea that facilitating the development of undergrowth vegetation may turn forestry stands into secondary habitats as opposed to their containing no habitat for native mammals. This forestry practice could contribute to conservation of biological diversity as it pertains to CBD targets.