Interpersonal violence in prehistoric San Pedro de Atacama, Chile: behavioral implications of environmental stress

The prehistoric population of San Pedro de Atacama lived through periods marked by prosperity and interregional interaction, as well as times of severe drought, social stress, and widespread poverty. A sample of 682 crania was analyzed for evidence of cranial trauma in order to assess changing patterns of interpersonal violence during the occupation of the oasis. It was hypothesized that the level of traumatic injuries in this population would parallel some of the changes seen in the archaeological record. Low fracture rates would be expected in periods of affluence and environmental stability, while periods characterized by environmental extremes and state collapse would yield elevated rates of aggression. This analysis found that rates of trauma escalated from 5.1% (5/99) in the earliest period, to 10.9% (10/92) in the Middle Horizon (AD 600-950). Although it may reflect problems related to increasing population density in the oasis, this increase is surprising, given that the early period witnessed the shift to permanent settlements, and the middle period was one of prosperity and plentiful resource availability. Trauma rates peaked at 35.6% (16/45) in an early Late Intermediate period (AD 950-1400) cemetery, with other Late Intermediate cemeteries demonstrating similarly high rates of traumatic injury. The elevated trauma rates during this period correlate with major droughts, the concentration of settlements on the oasis' east side, fortified structures, and material poverty, all reflected in the archaeological record. As the Late Intermediate waned and environmental conditions improved, trauma concomitantly decreased (7.0%), and remained low throughout the Inka occupation (AD 1400-1532). This indicates that while the Atacama was not peaceful, violence became commonplace only during periods of great social change and resource stress.     

Integrative taxonomy reveals cryptic Amazonian species of Pristimantis (Anura: Strabomantidae)

Hypotheses on the taxonomic status of two Bolivian Pristimantis with taxonomic problems are assessed by an integrative taxonomic approach that integrates three independent lines of evidence: external morphology, prezygotic reproductive barriers (advertisement calls) and reciprocal monophyly (phylogenetic analyses of partial 16S mtDNA sequences). Central Andean Bolivian populations previously assigned to either P. peruvianus or P. dundeei, and lowland Amazonian populations from southern Peru and northern Bolivia previously considered P. peruvianus do not correspond to these species. Indeed, multivariate analyses of qualitative and quantitative morphological and bioacoustic characters, and phylogenetic analyses support the hypothesis that they represent different, previously unknown, cryptic lineages. They are herein described as new species. The former is a sibling species of P. fenestratus that inhabits the Amazonian and semideciduous forests of the Andean foothills in central Bolivia. The latter is sibling to the Andean species P. danae and is parapatric to it in the Amazonian lowland forests and adjacent foothills of northern Bolivia, southern Peru and adjacent Brazil. Most species of Neotropical frogs, and especially Pristimantis, have been described by using external qualitative morphological characters only. An extended integrative taxonomic approach, as exemplified herein, may lead to the discovery of many other cryptic and sibling lineages that would increase the species numbers of tropical areas. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 97–122.     

Nest orientation of the Spotted Barbtail, <Emphasis Type="Italic">Premnoplex brunnescens</Emphasis>, is strongly correlated with stream flow

The placement and orientation of bird nests may strongly influence reproductive success. For many species, nest orientation is related to the cardinal directions and has to do with prevailing winds or solar exposure. Nest orientation differs among species in different environments, variously cooling or warming nests to maintain a nest microclimate optimal for successful development of eggs and young. The Spotted Barbtail (Premnoplex brunnescens) builds mossy, enclosed nests along shaded streams in Neotropical cloud forests. It shows a unique pattern of nest orientation, whereby nests are oriented in relation to the direction of water flowing below the nest entrance, rather than compass bearing. Nests face in one of three directions in relation to the stream: downstream, upstream, or perpendicular to the flow of the water. I discuss the ability of various hypotheses to explain this pattern in the context of factors affecting nest orientation in other species. While the reasons for this pattern of orientation remain unclear, orientation is likely driven by the need to create and maintain an optimal internal nest microclimate.     

Agriculture and Inequality in the Colonial Andes: A Simulation of Production and Consumption Using Administrative Documents

During the sixteenth and seventeenth centuries, indigenous communities in the Viceroyalty of Peru suffered forced resettlement, introduced disease, and onerous colonial tribute levies. These produced an onslaught of petitions for new tribute counts, as their diminished populations were obliged to pay the head taxes set by earlier censuses. The resulting visitas (administrative surveys) provide a wealth of information on the demography and agricultural systems of colonial Andean communities. However, comparatively little quantitative research exists on the distribution of agricultural resources and the nutritional demands of households. We model agricultural production and nutritional demand using household demographic and landholding declarations in the visitas from the Colca Valley of southern highland Peru, combined with ethnographically-derived estimates of agricultural production and nutritional demand. The results indicate that despite surplus agricultural production in the aggregate, there were significant differences in intra- and inter-community land wealth and production sufficiency ratios, leaving about 30% of households with caloric shortfalls. In contrast to regional-scale carrying capacity-type models, this simulation characterizes agricultural inequality within colonial Andean communities, and thus accounts for the hardship evidenced by tributary recount petitions, even in a breadbasket province from which much surplus production was extracted to fill colonial coffers.

A threshold response to habitat disturbance by forest birds in the Choco Andean corridor, Northwest Ecuador

Understanding how organisms use disturbed habitats and how that use can be increased is a pivotal question in conservation biology. We analyzed the relationship between upper canopy cover, a measure of disturbance, and habitat occupancy and use by 18 forest bird species in northwest Ecuador. From May 22 to June 28, 2006 we conducted five, 10-min 50 m-radius point counts at each of the 28 sites (140 total) representing a gradient of habitat disturbance from 1,285 to 1,787 m in elevation. Both habitat occupancy and use showed strong threshold responses at 21–40% upper canopy cover with the probability of occupancy increasing from about 0 to 1 and emigration (the probability that a species would stop using the site during the study period) decreasing from about 1 to 0. Bird surveys ended near the beginning of the driest time of year and high levels of emigration in more disturbed areas imply that forest birds stopped using these areas as the dry season approached, possibly due to a shift in food resources. Patterns of habitat use and occupancy suggest that disturbed habitat in the region (which is primarily abandoned pasture) may only be valuable to forest birds after a specific level of regeneration and during certain times of the year.     

Systematic conservation assessment for the Mesoamerica, Chocó, and Tropical Andes biodiversity hotspots: a preliminary analysis

Using IUCN Red List species as biodiversity surrogates, supplemented with additional analyses based on ecoregional diversity, priority areas for conservation in Mesoamerica, Chocó, and the Tropical Andes were identified using the methods of systematic conservation planning. Species’ ecological niches were modeled from occurrence records using a maximum entropy algorithm. Niche models for 78 species were refined to produce geographical distributions. Areas were prioritized for conservation attention using a complementarity-based algorithm implemented in the ResNet software package. Targets of representation for Red List species were explored from 10 to 90% of the modeled distributions at 10% increments; for the 53 ecoregions, the target was 10% for each ecoregion. Selected areas were widely dispersed across the region, reflecting the widespread distribution of Red List species in Mesoamerica, Chocó, and the Tropical Andes, which underscores the region’s importance for biodiversity. In general, existing protected areas were no more representative of biodiversity than areas outside them. Among the countries in the region, the protected areas of Belize performed best and those of Colombia and Ecuador worst. A high representation target led to the selection of a very large proportion of each country except Colombia and Ecuador (for a 90% target, 83–95% of each country was selected). Since such large proportions of land cannot realistically be set aside as parks or reserves, biodiversity conservation in Mesoamerica, Chocó, and the Tropical Andes will require integrative landscape management which combines human use of the land with securing the persistence of biota. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Unusual incubation rhythms the Spotted Barbtail, Premnoplex brunnescens

The Spotted Barbtail (Premnoplex brunnescens) inhabits the understory of humid montane forests in Central and South America. Apart from basic information on eggs and nest form, little has been published on its breeding ecology. Using temperature sensors in nest cups, I have collected data on the diurnal patterns of egg-coverage from three nests in eastern Ecuador and reveal a remarkable incubation rhythm. After providing near-constant coverage during the morning, adults leave the eggs unattended for most of the afternoon, returning to the nest only in the late afternoon. The mean duration (±standard deviation) of this period of absence, across the entire incubation period at three nests, was 6.4 ± 1.9 h. These results are discussed in relation to their physiological and ecological significance.     

Paraphyly of Cinclodes fuscus (Aves: Passeriformes: Furnariidae): Implications for taxonomy and biogeography

The Andes are a hotspot of global avian diversity, but studies on the historical diversification of Andean birds remain relatively scarce. Evolutionary studies on avian lineages with Andean–Patagonian distributions have focused on reconstructing species-level phylogenies, whereas no detailed phylogeographic studies on widespread species have been conducted. Here, we describe phylogeographic patterns in the Bar-winged Cinclodes (Cinclodes fuscus), a widespread and common species of ovenbird (Furnariidae) that breeds from Tierra del Fuego to the northern Andes. Traditionally, C. fuscus has been considered a single species composed of nine subspecies, but its long and narrow range suggests the possibility of considerable genetic variation among populations. Sequences of two mitochondrial genes revealed three discrete and geographically coherent groups of C. fuscus, occupying the southern, central, and northern Andes. Surprisingly, phylogenetic analyses indicated that these groups were more closely related to other species of Cinclodes than to each other. Relationships of the southern and northern C. fuscus clades to other species of Cinclodes were straightforward; in combination with available information on plumage, behavioral, and vocal variation, this suggests that each should be recognized as a distinct biological species. The central Andean group was paraphyletic with respect to C. oustaleti, and relationships among these taxa and C. olrogi were poorly resolved. We suggest that the central Andean C. fuscus should also be considered a different species, pending new information to clarify species limits in this group. These new phylogenetic data, along with recently developed methods, allowed us to review the biogeography of the genus, confirming southern South America and the central Andes as important areas for the diversification of these birds.