Y-chromosome evidence for differing ancient demographic histories in the Americas

To scrutinize the male ancestry of extant Native American populations, we examined eight biallelic and six microsatellite polymorphisms from the nonrecombining portion of the Y chromosome, in 438 individuals from 24 Native American populations (1 Na Dené and 23 South Amerinds) and in 404 Mongolians. One of the biallelic markers typed is a recently identified mutation (M242) characterizing a novel founder Native American haplogroup. The distribution, relatedness, and diversity of Y lineages in Native Americans indicate a differentiated male ancestry for populations from North and South America, strongly supporting a diverse demographic history for populations from these areas. These data are consistent with the occurrence of two major male migrations from southern/central Siberia to the Americas (with the second migration being restricted to North America) and a shared ancestry in central Asia for some of the initial migrants to Europe and the Americas. The microsatellite diversity and distribution of a Y lineage specific to South America (Q-M19) indicates that certain Amerind populations have been isolated since the initial colonization of the region, suggesting an early onset for tribalization of Native Americans. Age estimates based on Y-chromosome microsatellite diversity place the initial settlement of the American continent at approximately 14,000 years ago, in relative agreement with the age of well-established archaeological evidence.     

Experimental evidence for a demographic cline in Panstrongylus megistus populations

The population biology of three populations of Panstrongylus megistus was compared to determine possible influence on the behaviour and epidemiological importance of this species. The results demonstrated differences in terms of egg eclosion time, nymphal mortality and development rates, and feeding and defaecation rates. These differences appeared to follow a geographical cline, primarily reflecting different degrees of adaptation to domestic habitats.     

Using phylogenetic, genetic and demographic evidence for setting conservation priorities for Mexican rare pines

Phylogenetic, genetic and demographic information are key issues for establishing priorities for conservation. In this study we explored the Vane-Wrigth measure of phylogenetic diversity for establishing criteria for conservation, when intra as well as interpopulation level demographic (population size) and genetic (heterozygosity, inbreeding and genetic distances among populations) parameters are taken into consideration. The data were standardized and analyzed independently and integratively enabling the calculation of indices or criteria for conservation priorities. We illustrate the application of this approach in populations of four Mexican pine species that have been considered rare and endangered, Pinus rzedowzkii, P. pinceana, P. lagunae and P. muricata. The application of several independent diversity indices did not allow us to resolve prioritization. However, the integration of all indices generated different values of importance to conservation, and suggested that the populations with the highest priorities for conservation are: two for Pinus rzedowskii, P. pinceana, and P. lagunae, and one for P. muricata. These populations have intermediate sizes, are the most divergent in the phylogeny and contain genetic variation that is representative of the gene pool of each species. Finally, we demonstrated the functionality of some genetic and demographic parameters; the genetic structure, recruitment rate, geographic distribution and demographic stochasticity, as complementary indicators for evaluating the conservation priority among populations and species.     

Molecular evidence for a recent demographic expansion in the puma (Puma concolor) (Mammalia,Felidae)

The puma is an iconic predator that ranges throughout the Americas, occupying diverse habitats. Previous phylogeographic analyses have revealed that it exhibits moderate levels of genetic structure across its range, with few of the classically recognized subspecies being supported as distinct demographic units. Moreover, most of the species’ molecular diversity was found to be in South America. To further investigate the phylogeographic structure and demographic history of pumas we analyzed mtDNA sequences from 186 individuals sampled throughout their range, with emphasis on South America. Our objectives were to refine the phylogeographic assessment within South America and to investigate the demographic history of pumas using a coalescent approach. Our results extend previous phylogeographic findings, reassessing the delimitation of historical population units in South America and demonstrating that this species experienced a considerable demographic expansion in the Holocene, ca. 8,000 years ago. Our analyses indicate that this expansion occurred in South America, prior to the hypothesized re-colonization of North America, which was therefore inferred to be even more recent. The estimated demographic history supports the interpretation that pumas suffered a severe demographic decline in the Late Pleistocene throughout their distribution, followed by population expansion and re-colonization of the range, initiating from South America.     

Patterns and causes of demographic variation in a harvested moose population: evidence for the effects of climate and density-dependent drivers

1.?Better understanding of the mechanisms affecting demographic variation in ungulate populations is needed to support sustainable management of harvested populations. While studies of moose Alces alces L. populations have previously explored temporal variation in demographic processes, managers responsible for populations that span large heterogeneous landscapes would benefit from an understanding of how demography varies across biogeographical gradients in climate and other population drivers. Evidence of thresholds in population response to manageable and un-manageable drivers could aid resource managers in identifying limits to the magnitude of sustainable change. 2.?Generalized additive models (GAMs) were used to evaluate the relative importance of population density, habitat abundance, summer and winter climatic conditions, primary production, and harvest intensity in explaining spatial variation in moose vital rates in Ontario, Canada. Tree regression was used to test for thresholds in the magnitudes of environmental predictor variables that significantly affected population vital rates. 3.?Moose population growth rate was negatively related to moose density and positively related to the abundance of mixed deciduous habitat abundant in forage. Calf recruitment was negatively related to a later start of the growing season and calf harvest. The ratio of bulls to cows was related to male harvest and hunter access, and thresholds were evident in predictor variables for all vital rate models. 4.?Findings indicate that the contributions of density-dependent and independent factors can vary depending on the scale of population process. The importance of density dependence and habitat supply to low-density ungulate populations was evident, and management strategies for ungulates may be improved by explicitly linking forest management and harvest. Findings emphasize the importance of considering summer climatic influences to ungulate populations, as recruitment in moose was more sensitive to the timing of vegetation green-up than winter severity. The efficacy of management decisions for harvested ungulates may require regional shifts in targets where populations span bioclimatic gradients. The use of GAMs in combination with recursive partitioning was demonstrated to be an informative analytical framework that captured nonlinear relationships common in natural processes and thresholds that are relevant to population management in diverse systems.     

Multiple lines of evidence for demographic and range expansion of a temperate species (Hyla sarda) during the last glaciation

Many temperate species experienced demographic and range contractions in response to climatic changes during Pleistocene glaciations. In this study, we investigate the evolutionary history of the Tyrrhenian tree frog Hyla sarda, a species inhabiting the Corsica-Sardinia island system (Western Mediterranean basin). We used sequence analysis of two mitochondrial (overall 1229 bp) and three nuclear (overall 1692 bp) gene fragments to assess the phylogeography and demographic history of this species, and species distribution modelling (SDM) to predict its range variation over time. Phylogeographic, historical demographic and SDM analyses consistently indicate that H. sarda does not conform to the scenario generally expected for temperate species but rather underwent demographic and range expansion mostly during the last glacial phase. Palaeogeographic data and SDM analyses suggest that such expansion was driven by the glaciation-induced increase in lowland areas during marine regression. This unusual scenario suggests that at least some temperate species may not have suffered the adverse effects of glacial climate on their population size and range extent, owing to the mitigating effects of other glaciations-induced palaeoenvironmental changes. We discuss previous clues for the occurrence of such a scenario in other species and some possible challenges with its identification. Early phylogeographic literature suggested that responses to the Pleistocene glacial-interglacial cycles were expected to vary among species and regions. Our results point out that such variation may have been greater than previously thought.     

Patchy population structure in a short-distance migrant: evidence from genetic and demographic data

Species often occur in subdivided populations as a consequence of spatial heterogeneity of the habitat. To describe the spatial organization of subpopulations, existing theory proposes three main population models: patchy population, metapopulation and isolated populations. These models differ in their predicted levels of connectivity among subpopulations, and in the risk that a subpopulation will go extinct. However, spatially discrete subpopulations are commonly considered to be organized as metapopulations, even though explicit tests of metapopulation assumptions are rare. Here, we test predictions of the three models on the basis of demographic and genetic data, a combined approach so far surprisingly little used in mobile organisms. From 2002 to 2005, we studied nine subpopulations of the wetland-restricted reed bunting ( Emberiza schoeniclus ) in the southeastern part of the Canton Zurich (Switzerland), from which local declines of this species have been reported. Here, wetlands are as small as 2.7 ha and separated through intensively used agricultural landscapes. Demographic data consisted of dispersal of colour-banded individuals among subpopulations, immigration rates and extinction-/recolonization dynamics. Genetic data were based on the distribution of genetic variability and gene flow among subpopulations derived from the analysis of nine microsatellite loci. Both demographic and genetic data revealed that the patchy population model best described the spatial organization of reed bunting subpopulations. High levels of dispersal among subpopulations, high immigration into the patchy population, and genetic admixture suggested little risk of extinction of both subpopulations and the entire patchy population. This study exemplifies the idea that spatially discrete subpopulations may be organized in ways other than a metapopulation, and hence has implications for the conservation of subpopulations and species.     

Graph decompositions for demographic loop analysis

A new approach to loop analysis is presented in which decompositions of the total elasticity of a population projection matrix over a set of life history pathways are obtained as solutions of a constrained system of linear equations. In loop analysis, life history pathways are represented by loops in the life cycle graph, and the elasticity of the loop is interpreted as a measure of the contribution of the life history pathway to the population growth rate. Associated with the life cycle graph is a vector space -- the cycle space of the graph -- which is spanned by the loops. The elasticities of the transitions in the life cycle graph can be represented by a vector in the cycle space, and a loop decomposition of the life cycle graph is then defined to be any nonnegative linear combination of the loops which sum to the vector of elasticities. In contrast to previously published algorithms for carrying out loop analysis, we show that a given life cycle graph admits of either a unique loop decomposition or an infinite set of loop decompositions which can be characterized as a bounded convex set of nonnegative vectors. Using this approach, loop decompositions which minimize or maximize a linear objective function can be obtained as solutions of a linear programming problem, allowing us to place lower and upper bounds on the contributions of life history pathways to the population growth rate. Another consequence of our approach to loop analysis is that it allows us to identify the exact tradeoffs in contributions to the population growth rate that must exist between life history pathways.     

Beyond Picturing Culture: A Critique of a Critique

Picturing Culture: Explorations of Film and Anthropology. Jay Ruby. Chicago: University of Chicago Press, 2000. 339 pp.     

Estimating demographic models for the range dynamics of plant species

Aims To better understand how demographic processes shape the range dynamics of woody plants (in this case, Proteaceae), we introduce a likelihood framework for fitting process‐based models of range dynamics to spatial abundance data. Location The fire‐prone Fynbos biome (Cape Floristic Region, South Africa). Methods Our process‐based models have a spatially explicit demographic submodel (describing dispersal, reproduction, mortality and local extinction) as well as an observation submodel (describing imperfect detection of individuals), and are constrained by species‐specific predictions of habitat distribution models and process‐based models for seed dispersal by wind. Free model parameters were varied to find parameter sets with the highest likelihood. After testing this approach with simulated data, we applied it to eight Proteaceae species that differ in breeding system (monoecy versus dioecy) and adult fire survival. We assess the importance of Allee effects and negative density dependence for range dynamics, by using the Akaike information criterion to select between alternative models fitted for the same species. Results The best model for all dioecious study species included Allee effects, whereas this was true for only one of four monoecious species. As expected, sprouters (in which adults survive fire) were estimated to have lower rates of reproduction and catastrophic population extinction than related non‐sprouters. Overcompensatory population dynamics seem important for three of four non‐sprouters. We also found good quantitative agreement between independent data and most estimates of reproduction, carrying capacity and extinction probability. Main conclusions This study shows that process‐based models can quantitatively describe how large‐scale abundance distributions arise from the movement and interaction of individuals. It stresses links between the life history, demography and range dynamics of Proteaceae: dioecious species seem more susceptible to Allee effects which reduce migration ability and increase local extinction risk, and sprouters seem to have high persistence of established populations, but their low reproduction limits habitat colonization and migration.     

Biotechnology and the Critique of Globalisation

This paper argues that human ambivalence toward global forces and biopower is grounded in age-old anxieties about the strange, the new, and the other, and that these anxieties reflect the extent to which people feel that they are in control of the forces impinging on their local moral worlds. Tolerance of risk is thus a function of ontological security, and will be experienced very differently in the North and the South.     

Men in the demographic transition

Women’s fertility is the focus of most demographic analyses, for in most mammals, and in many preindustrial societies, variance in male fertility, while an interesting biological phenomenon, is irrelevant. Yet in monogamous societies, the reproductive ecology of men, as well as that of women, is important is creating reproductive patterns. In nineteenth-century Sweden, the focus of this study, male reproductive ecology responded to resource conditions: richer men had more children than poorer men. Men’s fertility also interacted with local and historical factors in complex ways to have significant impact on population growth. As a result, “the” demographic transition was local, and locally reversible, in Sweden. Results cannot be simply translated from nineteenth-century studies to current attempts to promote fertility decline, because today, male and female resource-fertility curves differ in shape, not only in magnitude. When we translate studies of fertility decline, it is important to study individual fertility and to discern whether, in any particular case, male and female patterns are similar. Bobbi S. Low is Professor of Resource Ecology at the School of Natural Resources and Environment. Her background is in behavioral and evolutionary ecology and her current research interests are human sex differences in risk-taking and resource use.     

Interpreting the demographic changes.

The paper sets out the novel shape of current Western populations as to age composition, and demonstrates that their drastic ageing has been virtually instantaneous. European populations are described as uniquely old, with no precedent whatever in human history. Moreover, all the world''s populations are undergoing the same process, including those of the developing societies, at an even faster pace. The general failure of people at large to recognize the process, and their persistent, entirely anachronistic attitudes to the older members of their societies, is described as cultural lag. The development now beginning of the so-called bean-pole family, vertical kin links between contemporary relatives stretching over four generations or more, with progressively fewer lateral linkages, is sketched out. The necessity of all persons having to live in the presence of their future selves is insisted on, with its corollary about having to pay personally in lowered subsistence levels for the doubled life span. The emergence of what is termed a third age is run over, and it is suggested that its presence might create a new civilization, one of the features of which might be the absence of enforced idleness due to unemployment.     

Beyond Critique: Rethinking Roles for the Anthropology of Mental Health

The current supremacy of the ‘bio-bio-bio’ model within the discipline of psychiatry has progressively marginalized social science approaches to mental health. This situation begs the question, what role is there for the anthropology of mental health? In this essay, I contend that there are three essential roles for the anthropology of mental health in an era of biological psychiatry. These roles are to (i) provide a meaningful critique of practices, beliefs, and movements within current psychiatry; (ii) illuminate the socio-cultural, clinical, and familial context of suffering and healing regarding emotional distress/mental illness; and (iii) act as a catalyst for positive change regarding healing, services and provisions for people with emotional distress/mental illness. My argument is unified by my contention that a credible anthropology of mental health intending to make a societal contribution should offer no opposition without proposition. In other words, any critique must be counter-balanced by the detailing of solutions and proposals for change. This will ensure that the anthropology of mental health continues to contribute critical knowledge to the understanding of mental suffering, distress, and healing. Such social and cultural approaches are becoming especially important given the widespread disenchantment with an increasingly dominant biological psychiatry.