Demographic history and genetic differentiation in apes

SummaryComparisons of genetic variation between humans and great apes are hampered by the fact that we still know little about the demographics and evolutionary history of the latter species [1–4]. In addition, characterizing ape genetic variation is important because they are threatened with extinction, and knowledge about genetic differentiation among groups may guide conservation efforts [5]. We sequenced multiple intergenic autosomal regions totaling 22,400 base pairs (bp) in ten individuals each from western, central, and eastern chimpanzee groups and in nine bonobos, and 16,000 bp in ten Bornean and six Sumatran orangutans. These regions are analyzed together with homologous information from three human populations and gorillas. We find that whereas orangutans have the highest diversity, western chimpanzees have the lowest, and that the demographic histories of most groups differ drastically. Special attention should therefore be paid to sampling strategies and the statistics chosen when comparing levels of variation within and among groups. Finally, we find that the extent of genetic differentiation among “subspecies” of chimpanzees and orangutans is comparable to that seen among human populations, calling the validity of the “subspecies” concept in apes into question

Demographic shocks: the view from history

The paper will basically deal with four issues. The first one puts current changes or shifts into a historical comparative perspective. The second deals with "traditional" shocks or violent disturbances of the system and their consequences. The third discusses the "seismic" changes experienced in the past, attempts their measurement, and exemplifies their effects on population and society. The fourth deals with the relevance that past experience has for current changes.Demography ; Economic conditions

Demographic shocks: the view from history: discussion

I must admit from the onset that I cannot really be very critical of Massimo Livi-Bacci's work, because much if not most of what I know of historical demography I learned from him, and thus if I were overly critical of him, I would be in the position of spitting into the well from which I have drunk. This is a nice and well-argued paper, although for those of us who have been keeping up with Livi-Bacci's books, there is little here that we did not know before or at least were prepared to believe. But his essay, all the same, is so informed and so chock-full of insights that it inspired me to try to formalize and reflect on some of the things that he talks about, and how we should think about demographic shocks and the impact of political and economic events on mortality, fertility, and similar variables.Demography ; Economic conditions

Demographic shocks: the view from history: discussion

Massimo Livi-Bacci has taken us on a fascinating tour of demographic history. What lessons for developments in the world today can we draw from the story he tells? I will distinguish between three types of lessons, which I call "economic lessons," "demographic lessons," and "cultural/political lessons."Demography ; Economic conditions

A visual history of demographic projections in Australia

This fact sheet compares historic demographic patterns and central projections from the Australian Bureau of Statistics and the Australian Treasury. It looks at trends relating to the total population, population ageing, fertility, life expectancy and migration. Treasury figures are of particular interest since they form the basis for the Intergenerational Report, an analysis of fiscal sustainability of existing policy. Both the ABS and Treasury emphasise that in describing Australia’s future demography (as well as the related long term fiscal impacts) their figures should be seen as projections, not forecasts. But the two are commonly conflated in public and political discourse and the projections have an impact on policy decisions. So the reasonableness of official projections should be subject to scrutiny, evaluated against actual experience and compared to each other. Any differences and inaccuracies can serve as a guide to users of the data.  Transparency is all the more necessary given that the Treasury sets its own demographic assumptions for long-term fiscal reporting rather than using those produced by an independent national statistics office – the usual approach among OECD countries. The fact sheet shows how outcomes can differ based on different assumptions and how it is not uncommon for projections and assumptions to stray from reality

Mitochondrial phylogeography and demographic history of the Vicuña: implications for conservation

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275 000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22°S) dry Andes 14–12 000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29°S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts